first commit

mod/forum/classes/local/builders/exported_discussion.php

@@ -0,0 +1,155 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Exported discussion builder class.
+ *
+ * @package    mod_forum
+ * @copyright  2019 Peter Dias<peter@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_forum\local\builders;
+
+defined('MOODLE_INTERNAL') || die();
+
+use mod_forum\local\entities\discussion as discussion_entity;
+use mod_forum\local\entities\forum as forum_entity;
+use mod_forum\local\factories\legacy_data_mapper as legacy_data_mapper_factory;
+use mod_forum\local\factories\exporter as exporter_factory;
+use mod_forum\local\factories\vault as vault_factory;
+use rating_manager;
+use renderer_base;
+use stdClass;
+
+/**
+ * Exported discussion builder class
+ *
+ * This class is an implementation of the builder pattern (loosely). It is responsible
+ * for taking a set of related forums, discussions, and posts and generate the exported
+ * version of the discussion.
+ *
+ * It encapsulates the complexity involved with exporting discussions. All of the relevant
+ * additional resources will be loaded by this class in order to ensure the exporting
+ * process can happen.
+ *
+ * See this doc for more information on the builder pattern:
+ * https://designpatternsphp.readthedocs.io/en/latest/Creational/Builder/README.html
+ *
+ * @copyright  2019 Peter Dias<peter@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class exported_discussion {
+    /** @var renderer_base $renderer Core renderer */
+    private $renderer;
+
+    /** @var legacy_data_mapper_factory $legacydatamapperfactory Data mapper factory */
+    private $legacydatamapperfactory;
+
+    /** @var exporter_factory $exporterfactory Exporter factory */
+    private $exporterfactory;
+
+    /** @var vault_factory $vaultfactory Vault factory */
+    private $vaultfactory;
+
+    /** @var rating_manager $ratingmanager Rating manager */
+    private $ratingmanager;
+
+    /**
+     * Constructor.
+     *
+     * @param renderer_base $renderer Core renderer
+     * @param legacy_data_mapper_factory $legacydatamapperfactory Legacy data mapper factory
+     * @param exporter_factory $exporterfactory Exporter factory
+     * @param vault_factory $vaultfactory Vault factory
+     * @param rating_manager $ratingmanager Rating manager
+     */
+    public function __construct(
+        renderer_base $renderer,
+        legacy_data_mapper_factory $legacydatamapperfactory,
+        exporter_factory $exporterfactory,
+        vault_factory $vaultfactory,
+        rating_manager $ratingmanager
+    ) {
+        $this->renderer = $renderer;
+        $this->legacydatamapperfactory = $legacydatamapperfactory;
+        $this->exporterfactory = $exporterfactory;
+        $this->vaultfactory = $vaultfactory;
+        $this->ratingmanager = $ratingmanager;
+    }
+
+    /**
+     * Build any additional variables for the exported discussion for a given set of discussions.
+     *
+     * This will typically be used for a list of discussions in the same forum.
+     *
+     * @param stdClass $user The user to export the posts for.
+     * @param forum_entity $forum The forum that each of the $discussions belong to
+     * @param discussion_entity $discussion A list of all discussions that each of the $posts belong to
+     * @return stdClass[] List of exported posts in the same order as the $posts array.
+     */
+    public function build(
+        stdClass $user,
+        forum_entity $forum,
+        discussion_entity $discussion
+    ): array {
+
+        $favouriteids = [];
+        if ($this->is_favourited($discussion, $forum->get_context(), $user)) {
+            $favouriteids[] = $discussion->get_id();
+        }
+
+        $groupsbyid = $this->get_groups_available_in_forum($forum);
+        $discussionexporter = $this->exporterfactory->get_discussion_exporter(
+            $user, $forum, $discussion, $groupsbyid, $favouriteids
+        );
+
+        return (array) $discussionexporter->export($this->renderer);
+    }
+
+    /**
+     * Get the groups details for all groups available to the forum.
+     * @param forum_entity $forum The forum entity
+     * @return stdClass[]
+     */
+    private function get_groups_available_in_forum($forum): array {
+        $course = $forum->get_course_record();
+        $coursemodule = $forum->get_course_module_record();
+
+        return groups_get_all_groups($course->id, 0, $coursemodule->groupingid);
+    }
+
+    /**
+     * Check whether the provided discussion has been favourited by the user.
+     *
+     * @param discussion_entity $discussion The discussion record
+     * @param \context_module $forumcontext Forum context
+     * @param \stdClass $user The user to check the favourite against
+     *
+     * @return bool Whether or not the user has favourited the discussion
+     */
+    public function is_favourited(discussion_entity $discussion, \context_module $forumcontext, \stdClass $user) {
+        if (!isloggedin()) {
+            return false;
+        }
+
+        $usercontext = \context_user::instance($user->id);
+        $ufservice = \core_favourites\service_factory::get_service_for_user_context($usercontext);
+        return $ufservice->favourite_exists('mod_forum', 'discussions', $discussion->get_id(), $forumcontext);
+    }
+
+
+}

mod/forum/classes/local/builders/exported_discussion_summaries.php

@@ -0,0 +1,299 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Exported discussion summaries builder class.
+ *
+ * @package    mod_forum
+ * @copyright  2019 Mihail Geshoski <mihail@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_forum\local\builders;
+
+defined('MOODLE_INTERNAL') || die();
+
+use mod_forum\local\entities\discussion as discussion_entity;
+use mod_forum\local\entities\forum as forum_entity;
+use mod_forum\local\entities\post as post_entity;
+use mod_forum\local\factories\legacy_data_mapper as legacy_data_mapper_factory;
+use mod_forum\local\factories\exporter as exporter_factory;
+use mod_forum\local\factories\vault as vault_factory;
+use mod_forum\local\factories\manager as manager_factory;
+use rating_manager;
+use renderer_base;
+use stdClass;
+
+/**
+ * Exported discussion summaries builder class.
+ *
+ * This class is an implementation of the builder pattern (loosely). It is responsible
+ * for taking a set of related forums, discussions, and posts and generate the exported
+ * version of the discussion summaries.
+ *
+ * It encapsulates the complexity involved with exporting discussions summaries. All of the relevant
+ * additional resources will be loaded by this class in order to ensure the exporting
+ * process can happen.
+ *
+ * See this doc for more information on the builder pattern:
+ * https://designpatternsphp.readthedocs.io/en/latest/Creational/Builder/README.html
+ *
+ * @package    mod_forum
+ * @copyright  2019 Mihail Geshoski <mihail@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class exported_discussion_summaries {
+    /** @var renderer_base $renderer Core renderer */
+    private $renderer;
+
+    /** @var legacy_data_mapper_factory $legacydatamapperfactory Data mapper factory */
+    private $legacydatamapperfactory;
+
+    /** @var exporter_factory $exporterfactory Exporter factory */
+    private $exporterfactory;
+
+    /** @var vault_factory $vaultfactory Vault factory */
+    private $vaultfactory;
+
+    /** @var manager_factory $managerfactory Manager factory */
+    private $managerfactory;
+
+    /** @var rating_manager $ratingmanager Rating manager */
+    private $ratingmanager;
+
+    /**
+     * Constructor.
+     *
+     * @param renderer_base $renderer Core renderer
+     * @param legacy_data_mapper_factory $legacydatamapperfactory Legacy data mapper factory
+     * @param exporter_factory $exporterfactory Exporter factory
+     * @param vault_factory $vaultfactory Vault factory
+     * @param manager_factory $managerfactory Manager factory
+     */
+    public function __construct(
+        renderer_base $renderer,
+        legacy_data_mapper_factory $legacydatamapperfactory,
+        exporter_factory $exporterfactory,
+        vault_factory $vaultfactory,
+        manager_factory $managerfactory
+    ) {
+        $this->renderer = $renderer;
+        $this->legacydatamapperfactory = $legacydatamapperfactory;
+        $this->exporterfactory = $exporterfactory;
+        $this->vaultfactory = $vaultfactory;
+        $this->managerfactory = $managerfactory;
+        $this->ratingmanager = $managerfactory->get_rating_manager();
+    }
+
+    /**
+     * Build the exported discussion summaries for a given set of discussions.
+     *
+     * This will typically be used for a list of discussions in the same forum.
+     *
+     * @param stdClass $user The user to export the posts for.
+     * @param forum_entity $forum The forum that each of the $discussions belong to
+     * @param discussion_summary_entity[] $discussions A list of all discussion summaries to export
+     * @return stdClass[] List of exported posts in the same order as the $posts array.
+     */
+    public function build(
+        stdClass $user,
+        forum_entity $forum,
+        array $discussions
+    ): array {
+        $capabilitymanager = $this->managerfactory->get_capability_manager($forum);
+        $canseeanyprivatereply = $capabilitymanager->can_view_any_private_reply($user);
+
+        $discussionids = array_keys($discussions);
+
+        $postvault = $this->vaultfactory->get_post_vault();
+        $posts = $postvault->get_from_discussion_ids($user, $discussionids, $canseeanyprivatereply);
+        $groupsbyid = $this->get_groups_available_in_forum($forum);
+        $groupsbyauthorid = $this->get_author_groups_from_posts($posts, $forum);
+
+        $replycounts = $postvault->get_reply_count_for_discussion_ids($user, $discussionids, $canseeanyprivatereply);
+        $latestposts = $postvault->get_latest_posts_for_discussion_ids($user, $discussionids, $canseeanyprivatereply);
+        $latestauthors = $this->get_latest_posts_authors($latestposts);
+        $latestpostsids = array_map(function($post) {
+            return $post->get_id();
+        }, $latestposts);
+
+        $postauthorids = array_unique(array_reduce($discussions, function($carry, $summary) use ($latestposts){
+            $firstpostauthorid = $summary->get_first_post_author()->get_id();
+            $discussion = $summary->get_discussion();
+            $lastpostauthorid = $latestposts[$discussion->get_id()]->get_author_id();
+            return array_merge($carry, [$firstpostauthorid, $lastpostauthorid]);
+        }, []));
+        $postauthorcontextids = $this->get_author_context_ids($postauthorids);
+
+        $unreadcounts = [];
+        $favourites = $this->get_favourites($user);
+        $forumdatamapper = $this->legacydatamapperfactory->get_forum_data_mapper();
+        $forumrecord = $forumdatamapper->to_legacy_object($forum);
+
+        if (forum_tp_can_track_forums($forumrecord)) {
+            $unreadcounts = $postvault->get_unread_count_for_discussion_ids($user, $discussionids, $canseeanyprivatereply);
+        }
+
+        $summaryexporter = $this->exporterfactory->get_discussion_summaries_exporter(
+            $user,
+            $forum,
+            $discussions,
+            $groupsbyid,
+            $groupsbyauthorid,
+            $replycounts,
+            $unreadcounts,
+            $latestpostsids,
+            $postauthorcontextids,
+            $favourites,
+            $latestauthors
+        );
+
+        $exportedposts = (array) $summaryexporter->export($this->renderer);
+        $firstposts = $postvault->get_first_post_for_discussion_ids($discussionids);
+
+        array_walk($exportedposts['summaries'], function($summary) use ($firstposts, $latestposts) {
+            $summary->discussion->times['created'] = (int) $firstposts[$summary->discussion->firstpostid]->get_time_created();
+            $summary->discussion->times['modified'] = (int) $latestposts[$summary->discussion->id]->get_time_created();
+        });
+
+        // Pass the current, preferred sort order for the discussions list.
+        $discussionlistvault = $this->vaultfactory->get_discussions_in_forum_vault();
+        $sortorder = get_user_preferences('forum_discussionlistsortorder',
+            $discussionlistvault::SORTORDER_LASTPOST_DESC);
+
+        $sortoptions = array(
+            'islastpostdesc' => $sortorder == $discussionlistvault::SORTORDER_LASTPOST_DESC,
+            'islastpostasc' => $sortorder == $discussionlistvault::SORTORDER_LASTPOST_ASC,
+            'isrepliesdesc' => $sortorder == $discussionlistvault::SORTORDER_REPLIES_DESC,
+            'isrepliesasc' => $sortorder == $discussionlistvault::SORTORDER_REPLIES_ASC,
+            'iscreateddesc' => $sortorder == $discussionlistvault::SORTORDER_CREATED_DESC,
+            'iscreatedasc' => $sortorder == $discussionlistvault::SORTORDER_CREATED_ASC,
+            'isdiscussiondesc' => $sortorder == $discussionlistvault::SORTORDER_DISCUSSION_DESC,
+            'isdiscussionasc' => $sortorder == $discussionlistvault::SORTORDER_DISCUSSION_ASC,
+            'isstarterdesc' => $sortorder == $discussionlistvault::SORTORDER_STARTER_DESC,
+            'isstarterasc' => $sortorder == $discussionlistvault::SORTORDER_STARTER_ASC,
+            'isgroupdesc' => $sortorder == $discussionlistvault::SORTORDER_GROUP_DESC,
+            'isgroupasc' => $sortorder == $discussionlistvault::SORTORDER_GROUP_ASC,
+        );
+
+        $exportedposts['state']['sortorder'] = $sortoptions;
+
+        return $exportedposts;
+    }
+
+    /**
+     * Get a list of all favourited discussions.
+     *
+     * @param stdClass $user The user we are getting favourites for
+     * @return int[] A list of favourited itemids
+     */
+    private function get_favourites(stdClass $user): array {
+        $ids = [];
+
+        if (isloggedin()) {
+            $usercontext = \context_user::instance($user->id);
+            $ufservice = \core_favourites\service_factory::get_service_for_user_context($usercontext);
+            $favourites = $ufservice->find_favourites_by_type('mod_forum', 'discussions');
+            foreach ($favourites as $favourite) {
+                $ids[] = $favourite->itemid;
+            }
+        }
+
+        return $ids;
+    }
+
+    /**
+     * Returns a mapped array of discussionid to the authors of the latest post
+     *
+     * @param array $latestposts Mapped array of discussion to latest posts.
+     * @return array Array of authors mapped to the discussion
+     */
+    private function get_latest_posts_authors($latestposts) {
+        $authors = $this->vaultfactory->get_author_vault()->get_authors_for_posts($latestposts);
+
+        $mappedauthors = array_reduce($latestposts, function($carry, $item) use ($authors) {
+            $carry[$item->get_discussion_id()] = $authors[$item->get_author_id()];
+
+            return $carry;
+        }, []);
+        return $mappedauthors;
+    }
+
+    /**
+     * Get the groups details for all groups available to the forum.
+     * @param forum_entity $forum The forum entity
+     * @return stdClass[]
+     */
+    private function get_groups_available_in_forum($forum): array {
+        $course = $forum->get_course_record();
+        $coursemodule = $forum->get_course_module_record();
+
+        return groups_get_all_groups($course->id, 0, $coursemodule->groupingid);
+    }
+
+    /**
+     * Get the author's groups for a list of posts.
+     *
+     * @param post_entity[] $posts The list of posts
+     * @param forum_entity $forum The forum entity
+     * @return array Author groups indexed by author id
+     */
+    private function get_author_groups_from_posts(array $posts, $forum): array {
+        $course = $forum->get_course_record();
+        $coursemodule = $forum->get_course_module_record();
+        $authorids = array_reduce($posts, function($carry, $post) {
+            $carry[$post->get_author_id()] = true;
+            return $carry;
+        }, []);
+        $authorgroups = groups_get_all_groups($course->id, array_keys($authorids), $coursemodule->groupingid,
+                'g.*, gm.id, gm.groupid, gm.userid');
+
+        $authorgroups = array_reduce($authorgroups, function($carry, $group) {
+            // Clean up data returned from groups_get_all_groups.
+            $userid = $group->userid;
+            $groupid = $group->groupid;
+
+            unset($group->userid);
+            unset($group->groupid);
+            $group->id = $groupid;
+
+            if (!isset($carry[$userid])) {
+                $carry[$userid] = [$group];
+            } else {
+                $carry[$userid][] = $group;
+            }
+
+            return $carry;
+        }, []);
+
+        foreach (array_diff(array_keys($authorids), array_keys($authorgroups)) as $authorid) {
+            $authorgroups[$authorid] = [];
+        }
+
+        return $authorgroups;
+    }
+
+    /**
+     * Get the user context ids for each of the authors.
+     *
+     * @param int[] $authorids The list of author ids to fetch context ids for.
+     * @return int[] Context ids indexed by author id
+     */
+    private function get_author_context_ids(array $authorids): array {
+        $authorvault = $this->vaultfactory->get_author_vault();
+        return $authorvault->get_context_ids_for_author_ids($authorids);
+    }
+}

mod/forum/classes/local/builders/exported_posts.php

@@ -0,0 +1,573 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Exported post builder class.
+ *
+ * @package    mod_forum
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_forum\local\builders;
+
+defined('MOODLE_INTERNAL') || die();
+
+use mod_forum\local\entities\discussion as discussion_entity;
+use mod_forum\local\entities\forum as forum_entity;
+use mod_forum\local\entities\post as post_entity;
+use mod_forum\local\factories\legacy_data_mapper as legacy_data_mapper_factory;
+use mod_forum\local\factories\exporter as exporter_factory;
+use mod_forum\local\factories\vault as vault_factory;
+use mod_forum\local\factories\manager as manager_factory;
+use core_tag_tag;
+use moodle_exception;
+use renderer_base;
+use stdClass;
+
+/**
+ * Exported post builder class.
+ *
+ * This class is an implementation of the builder pattern (loosely). It is responsible
+ * for taking a set of related forums, discussions, and posts and generate the exported
+ * version of the posts.
+ *
+ * It encapsulates the complexity involved with exporting posts. All of the relevant
+ * additional resources will be loaded by this class in order to ensure the exporting
+ * process can happen.
+ *
+ * See this doc for more information on the builder pattern:
+ * https://designpatternsphp.readthedocs.io/en/latest/Creational/Builder/README.html
+ *
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class exported_posts {
+    /** @var renderer_base $renderer Core renderer */
+    private $renderer;
+
+    /** @var legacy_data_mapper_factory $legacydatamapperfactory Data mapper factory */
+    private $legacydatamapperfactory;
+
+    /** @var exporter_factory $exporterfactory Exporter factory */
+    private $exporterfactory;
+
+    /** @var vault_factory $vaultfactory Vault factory */
+    private $vaultfactory;
+
+    /** @var rating_manager $ratingmanager Rating manager */
+    private $ratingmanager;
+
+    /** @var manager_factory $managerfactory Manager factory */
+    private $managerfactory;
+
+    /**
+     * Constructor.
+     *
+     * @param renderer_base $renderer Core renderer
+     * @param legacy_data_mapper_factory $legacydatamapperfactory Legacy data mapper factory
+     * @param exporter_factory $exporterfactory Exporter factory
+     * @param vault_factory $vaultfactory Vault factory
+     * @param manager_factory $managerfactory Manager factory
+     */
+    public function __construct(
+        renderer_base $renderer,
+        legacy_data_mapper_factory $legacydatamapperfactory,
+        exporter_factory $exporterfactory,
+        vault_factory $vaultfactory,
+        manager_factory $managerfactory
+    ) {
+        $this->renderer = $renderer;
+        $this->legacydatamapperfactory = $legacydatamapperfactory;
+        $this->exporterfactory = $exporterfactory;
+        $this->vaultfactory = $vaultfactory;
+        $this->managerfactory = $managerfactory;
+        $this->ratingmanager = $managerfactory->get_rating_manager();
+    }
+
+    /**
+     * Build the exported posts for a given set of forums, discussions, and posts.
+     *
+     * This will typically be used for a list of posts in the same discussion/forum however
+     * it does support exporting any arbitrary list of posts as long as the caller also provides
+     * a unique list of all discussions for the list of posts and all forums for the list of discussions.
+     *
+     * Increasing the number of different forums being processed will increase the processing time
+     * due to processing multiple contexts (for things like capabilities, files, etc). The code attempts
+     * to load the additional resources as efficiently as possible but there is no way around some of
+     * the additional overhead.
+     *
+     * Note: Some posts will be removed as part of the build process according to capabilities.
+     * A one-to-one mapping should not be expected.
+     *
+     * @param stdClass $user The user to export the posts for.
+     * @param forum_entity[] $forums A list of all forums that each of the $discussions belong to
+     * @param discussion_entity[] $discussions A list of all discussions that each of the $posts belong to
+     * @param post_entity[] $posts The list of posts to export.
+     * @param bool $includeinlineattachments Whether inline attachments should be included or not.
+     * @return stdClass[] List of exported posts in the same order as the $posts array.
+     */
+    public function build(
+        stdClass $user,
+        array $forums,
+        array $discussions,
+        array $posts,
+        bool $includeinlineattachments = false
+    ): array {
+        // Format the forums and discussion to make them more easily accessed later.
+        $forums = array_reduce($forums, function($carry, $forum) {
+            $carry[$forum->get_id()] = $forum;
+            return $carry;
+        }, []);
+        $discussions = array_reduce($discussions, function($carry, $discussion) {
+            $carry[$discussion->get_id()] = $discussion;
+            return $carry;
+        }, []);
+
+        // Group the posts by discussion and forum so that we can load the resources in
+        // batches to improve performance.
+        $groupedposts = $this->group_posts_by_discussion($forums, $discussions, $posts);
+        // Load all of the resources we need in order to export the posts.
+        $authorsbyid = $this->get_authors_for_posts($posts);
+        $authorcontextids = $this->get_author_context_ids(array_keys($authorsbyid));
+        $attachmentsbypostid = $this->get_attachments_for_posts($groupedposts);
+        $inlineattachments = [];
+        if ($includeinlineattachments) {
+            $inlineattachments = $this->get_inline_attachments_for_posts($groupedposts);
+        }
+        $groupsbycourseandauthorid = $this->get_author_groups_from_posts($groupedposts);
+        $tagsbypostid = $this->get_tags_from_posts($posts);
+        $ratingbypostid = $this->get_ratings_from_posts($user, $groupedposts);
+        $readreceiptcollectionbyforumid = $this->get_read_receipts_from_posts($user, $groupedposts);
+        $exportedposts = [];
+
+        // Export each set of posts per discussion because it's the largest chunks we can
+        // break them into due to constraints on capability checks.
+        foreach ($groupedposts as $grouping) {
+            [
+                'forum' => $forum,
+                'discussion' => $discussion,
+                'posts' => $groupedposts
+            ] = $grouping;
+
+            // Exclude posts the user cannot see, such as certain posts in Q and A forums.
+            $capabilitymanager = $this->managerfactory->get_capability_manager($forum);
+            $groupedposts = array_filter($groupedposts, function($post) use ($capabilitymanager, $user, $discussion) {
+                return $capabilitymanager->can_view_post($user, $discussion, $post);
+            });
+
+            $forumid = $forum->get_id();
+            $courseid = $forum->get_course_record()->id;
+            $postsexporter = $this->exporterfactory->get_posts_exporter(
+                $user,
+                $forum,
+                $discussion,
+                $groupedposts,
+                $authorsbyid,
+                $authorcontextids,
+                $attachmentsbypostid,
+                $groupsbycourseandauthorid[$courseid],
+                $readreceiptcollectionbyforumid[$forumid] ?? null,
+                $tagsbypostid,
+                $ratingbypostid,
+                true,
+                $inlineattachments
+            );
+            ['posts' => $exportedgroupedposts] = (array) $postsexporter->export($this->renderer);
+            $exportedposts = array_merge($exportedposts, $exportedgroupedposts);
+        }
+
+        if (count($forums) == 1 && count($discussions) == 1) {
+            // All of the posts belong to a single discussion in a single forum so
+            // the exported order will match the given $posts array.
+            return $exportedposts;
+        } else {
+            // Since we grouped the posts by discussion and forum the ordering of the
+            // exported posts may be different to the given $posts array so we should
+            // sort it back into the correct order for the caller.
+            return $this->sort_exported_posts($posts, $exportedposts);
+        }
+    }
+
+    /**
+     * Group the posts by which discussion they belong to in order for them to be processed
+     * in chunks by the exporting.
+     *
+     * Returns a list of groups where each group has a forum, discussion, and list of posts.
+     * E.g.
+     * [
+     *      [
+     *          'forum' => <forum_entity>,
+     *          'discussion' => <discussion_entity>,
+     *          'posts' => [
+     *              <post_entity in discussion>,
+     *              <post_entity in discussion>,
+     *              <post_entity in discussion>
+     *          ]
+     *      ]
+     * ]
+     *
+     * @param forum_entity[] $forums A list of all forums that each of the $discussions belong to, indexed by id.
+     * @param discussion_entity[] $discussions A list of all discussions that each of the $posts belong to, indexed by id.
+     * @param post_entity[] $posts The list of posts to process.
+     * @return array List of grouped posts. Each group has a discussion, forum, and posts.
+     */
+    private function group_posts_by_discussion(array $forums, array $discussions, array $posts): array {
+        return array_reduce($posts, function($carry, $post) use ($forums, $discussions) {
+            $discussionid = $post->get_discussion_id();
+            if (!isset($discussions[$discussionid])) {
+                throw new moodle_exception('Unable to find discussion with id ' . $discussionid);
+            }
+
+            if (isset($carry[$discussionid])) {
+                $carry[$discussionid]['posts'][] = $post;
+            } else {
+                $discussion = $discussions[$discussionid];
+                $forumid = $discussion->get_forum_id();
+
+                if (!isset($forums[$forumid])) {
+                    throw new moodle_exception('Unable to find forum with id ' . $forumid);
+                }
+
+                $carry[$discussionid] = [
+                    'forum' => $forums[$forumid],
+                    'discussion' => $discussions[$discussionid],
+                    'posts' => [$post]
+                ];
+            }
+
+            return $carry;
+        }, []);
+    }
+
+    /**
+     * Load the list of authors for the given posts.
+     *
+     * The list of authors will be indexed by the author id.
+     *
+     * @param post_entity[] $posts The list of posts to process.
+     * @return author_entity[]
+     */
+    private function get_authors_for_posts(array $posts): array {
+        $authorvault = $this->vaultfactory->get_author_vault();
+        return $authorvault->get_authors_for_posts($posts);
+    }
+
+    /**
+     * Get the user context ids for each of the authors.
+     *
+     * @param int[] $authorids The list of author ids to fetch context ids for.
+     * @return int[] Context ids indexed by author id
+     */
+    private function get_author_context_ids(array $authorids): array {
+        $authorvault = $this->vaultfactory->get_author_vault();
+        return $authorvault->get_context_ids_for_author_ids($authorids);
+    }
+
+    /**
+     * Load the list of all inline attachments for the posts. The list of attachments will be
+     * indexed by the post id.
+     *
+     * @param array $groupedposts List of posts grouped by discussions.
+     * @return stored_file[]
+     */
+    private function get_inline_attachments_for_posts(array $groupedposts): array {
+        $inlineattachmentsbypostid = [];
+        $postattachmentvault = $this->vaultfactory->get_post_attachment_vault();
+        $postsbyforum = array_reduce($groupedposts, function($carry, $grouping) {
+            ['forum' => $forum, 'posts' => $posts] = $grouping;
+
+            $forumid = $forum->get_id();
+            if (!isset($carry[$forumid])) {
+                $carry[$forumid] = [
+                    'forum' => $forum,
+                    'posts' => []
+                ];
+            }
+
+            $carry[$forumid]['posts'] = array_merge($carry[$forumid]['posts'], $posts);
+            return $carry;
+        }, []);
+
+        foreach ($postsbyforum as $grouping) {
+            ['forum' => $forum, 'posts' => $posts] = $grouping;
+            $inlineattachments = $postattachmentvault->get_inline_attachments_for_posts($forum->get_context(), $posts);
+
+            // Have to loop in order to maintain the correct indexes since they are numeric.
+            foreach ($inlineattachments as $postid => $attachment) {
+                $inlineattachmentsbypostid[$postid] = $attachment;
+            }
+        }
+
+        return $inlineattachmentsbypostid;
+    }
+
+    /**
+     * Load the list of all attachments for the posts. The list of attachments will be
+     * indexed by the post id.
+     *
+     * @param array $groupedposts List of posts grouped by discussions.
+     * @return stored_file[]
+     */
+    private function get_attachments_for_posts(array $groupedposts): array {
+        $attachmentsbypostid = [];
+        $postattachmentvault = $this->vaultfactory->get_post_attachment_vault();
+        $postsbyforum = array_reduce($groupedposts, function($carry, $grouping) {
+            ['forum' => $forum, 'posts' => $posts] = $grouping;
+
+            $forumid = $forum->get_id();
+            if (!isset($carry[$forumid])) {
+                $carry[$forumid] = [
+                    'forum' => $forum,
+                    'posts' => []
+                ];
+            }
+
+            $carry[$forumid]['posts'] = array_merge($carry[$forumid]['posts'], $posts);
+            return $carry;
+        }, []);
+
+        foreach ($postsbyforum as $grouping) {
+            ['forum' => $forum, 'posts' => $posts] = $grouping;
+            $attachments = $postattachmentvault->get_attachments_for_posts($forum->get_context(), $posts);
+
+            // Have to loop in order to maintain the correct indexes since they are numeric.
+            foreach ($attachments as $postid => $attachment) {
+                $attachmentsbypostid[$postid] = $attachment;
+            }
+        }
+
+        return $attachmentsbypostid;
+    }
+
+    /**
+     * Get the groups for each author of the given posts.
+     *
+     * The results are grouped by course and then author id because the groups are
+     * contextually related to the course, e.g. a single author can be part of two different
+     * sets of groups in two different courses.
+     *
+     * @param array $groupedposts List of posts grouped by discussions.
+     * @return array List of groups indexed by forum id and then author id.
+     */
+    private function get_author_groups_from_posts(array $groupedposts): array {
+        $groupsbyauthorid = [];
+        $authoridsbycourseid = [];
+
+        // Get the unique list of author ids for each course in the grouped
+        // posts. Grouping by course is the largest grouping we can achieve.
+        foreach ($groupedposts as $grouping) {
+            ['forum' => $forum, 'posts' => $posts] = $grouping;
+            $course = $forum->get_course_record();
+            $courseid = $course->id;
+
+            if (!isset($authoridsbycourseid[$courseid])) {
+                $coursemodule = $forum->get_course_module_record();
+                $authoridsbycourseid[$courseid] = [
+                    'groupingid' => $coursemodule->groupingid,
+                    'authorids' => []
+                ];
+            }
+
+            $authorids = array_map(function($post) {
+                return $post->get_author_id();
+            }, $posts);
+
+            foreach ($authorids as $authorid) {
+                $authoridsbycourseid[$courseid]['authorids'][$authorid] = $authorid;
+            }
+        }
+
+        // Load each set of groups per course.
+        foreach ($authoridsbycourseid as $courseid => $values) {
+            ['groupingid' => $groupingid, 'authorids' => $authorids] = $values;
+            $authorgroups = groups_get_all_groups(
+                $courseid,
+                array_keys($authorids),
+                $groupingid,
+                'g.*, gm.id, gm.groupid, gm.userid'
+            );
+
+            if (!isset($groupsbyauthorid[$courseid])) {
+                $groupsbyauthorid[$courseid] = [];
+            }
+
+            foreach ($authorgroups as $group) {
+                // Clean up data returned from groups_get_all_groups.
+                $userid = $group->userid;
+                $groupid = $group->groupid;
+
+                unset($group->userid);
+                unset($group->groupid);
+                $group->id = $groupid;
+
+                if (!isset($groupsbyauthorid[$courseid][$userid])) {
+                    $groupsbyauthorid[$courseid][$userid] = [];
+                }
+
+                $groupsbyauthorid[$courseid][$userid][] = $group;
+            }
+        }
+
+        return $groupsbyauthorid;
+    }
+
+    /**
+     * Get the list of tags for each of the posts. The tags will be returned in an
+     * array indexed by the post id.
+     *
+     * @param post_entity[] $posts The list of posts to load tags for.
+     * @return array Sets of tags indexed by post id.
+     */
+    private function get_tags_from_posts(array $posts): array {
+        $postids = array_map(function($post) {
+            return $post->get_id();
+        }, $posts);
+        return core_tag_tag::get_items_tags('mod_forum', 'forum_posts', $postids);
+    }
+
+    /**
+     * Get the list of ratings for each post. The ratings are returned in an array
+     * indexed by the post id.
+     *
+     * @param stdClass $user The user viewing the ratings.
+     * @param array $groupedposts List of posts grouped by discussions.
+     * @return array Sets of ratings indexed by post id.
+     */
+    private function get_ratings_from_posts(stdClass $user, array $groupedposts) {
+        $ratingsbypostid = [];
+        $postsdatamapper = $this->legacydatamapperfactory->get_post_data_mapper();
+        $postsbyforum = array_reduce($groupedposts, function($carry, $grouping) {
+            ['forum' => $forum, 'posts' => $posts] = $grouping;
+
+            $forumid = $forum->get_id();
+            if (!isset($carry[$forumid])) {
+                $carry[$forumid] = [
+                    'forum' => $forum,
+                    'posts' => []
+                ];
+            }
+
+            $carry[$forumid]['posts'] = array_merge($carry[$forumid]['posts'], $posts);
+            return $carry;
+        }, []);
+
+        foreach ($postsbyforum as $grouping) {
+            ['forum' => $forum, 'posts' => $posts] = $grouping;
+
+            if (!$forum->has_rating_aggregate()) {
+                continue;
+            }
+
+            $items = $postsdatamapper->to_legacy_objects($posts);
+            $ratingoptions = (object) [
+                'context' => $forum->get_context(),
+                'component' => 'mod_forum',
+                'ratingarea' => 'post',
+                'items' => $items,
+                'aggregate' => $forum->get_rating_aggregate(),
+                'scaleid' => $forum->get_scale(),
+                'userid' => $user->id,
+                'assesstimestart' => $forum->get_assess_time_start(),
+                'assesstimefinish' => $forum->get_assess_time_finish()
+            ];
+
+            $rm = $this->ratingmanager;
+            $items = $rm->get_ratings($ratingoptions);
+
+            foreach ($items as $item) {
+                $ratingsbypostid[$item->id] = empty($item->rating) ? null : $item->rating;
+            }
+        }
+
+        return $ratingsbypostid;
+    }
+
+    /**
+     * Get the read receipt collections for the given viewing user and each forum. The
+     * receipt collections will only be loaded for posts in forums that the user is tracking.
+     *
+     * The receipt collections are returned in an array indexed by the forum ids.
+     *
+     * @param stdClass $user The user viewing the posts.
+     * @param array $groupedposts List of posts grouped by discussions.
+     */
+    private function get_read_receipts_from_posts(stdClass $user, array $groupedposts) {
+        $forumdatamapper = $this->legacydatamapperfactory->get_forum_data_mapper();
+        $trackedforums = [];
+        $trackedpostids = [];
+
+        foreach ($groupedposts as $group) {
+            ['forum' => $forum, 'posts' => $posts] = $group;
+            $forumid = $forum->get_id();
+
+            if (!isset($trackedforums[$forumid])) {
+                $forumrecord = $forumdatamapper->to_legacy_object($forum);
+                $trackedforums[$forumid] = forum_tp_is_tracked($forumrecord, $user);
+            }
+
+            if ($trackedforums[$forumid]) {
+                foreach ($posts as $post) {
+                    $trackedpostids[] = $post->get_id();
+                }
+            }
+        }
+
+        if (empty($trackedpostids)) {
+            return [];
+        }
+
+        // We can just load a single receipt collection for all tracked posts.
+        $receiptvault = $this->vaultfactory->get_post_read_receipt_collection_vault();
+        $readreceiptcollection = $receiptvault->get_from_user_id_and_post_ids($user->id, $trackedpostids);
+        $receiptsbyforumid = [];
+
+        // Assign the collection to all forums that are tracked.
+        foreach ($trackedforums as $forumid => $tracked) {
+            if ($tracked) {
+                $receiptsbyforumid[$forumid] = $readreceiptcollection;
+            }
+        }
+
+        return $receiptsbyforumid;
+    }
+
+    /**
+     * Sort the list of exported posts back into the same order as the given posts.
+     * The ordering of the exported posts can often deviate from the given posts due
+     * to the process of exporting them so we need to sort them back into the order
+     * that the calling code expected.
+     *
+     * @param post_entity[] $posts The posts in the expected order.
+     * @param stdClass[] $exportedposts The list of exported posts in any order.
+     * @return stdClass[] Sorted exported posts.
+     */
+    private function sort_exported_posts(array $posts, array $exportedposts) {
+        $postindexes = [];
+        foreach (array_values($posts) as $index => $post) {
+            $postindexes[$post->get_id()] = $index;
+        }
+
+        $sortedexportedposts = [];
+
+        foreach ($exportedposts as $exportedpost) {
+            $index = $postindexes[$exportedpost->id];
+            $sortedexportedposts[$index] = $exportedpost;
+        }
+
+        return $sortedexportedposts;
+    }
+}

mod/forum/classes/local/container.php

@@ -0,0 +1,154 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Container class.
+ *
+ * @package    mod_forum
+ * @copyright  2018 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_forum\local;
+
+defined('MOODLE_INTERNAL') || die();
+
+use mod_forum\local\factories\renderer as renderer_factory;
+use mod_forum\local\factories\legacy_data_mapper as legacy_data_mapper_factory;
+use mod_forum\local\factories\entity as entity_factory;
+use mod_forum\local\factories\exporter as exporter_factory;
+use mod_forum\local\factories\manager as manager_factory;
+use mod_forum\local\factories\vault as vault_factory;
+use mod_forum\local\factories\builder as builder_factory;
+use mod_forum\local\factories\url as url_factory;
+
+/**
+ * Container class.
+ *
+ * This class provides helper methods with static configurations to get any
+ * of the factories from the "local" namespace.
+ *
+ * @copyright  2018 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class container {
+    /**
+     * Create the renderer factory.
+     *
+     * @return renderer_factory
+     */
+    public static function get_renderer_factory(): renderer_factory {
+        global $PAGE;
+
+        return new renderer_factory(
+            self::get_legacy_data_mapper_factory(),
+            self::get_exporter_factory(),
+            self::get_vault_factory(),
+            self::get_manager_factory(),
+            self::get_entity_factory(),
+            self::get_builder_factory(),
+            self::get_url_factory(),
+            $PAGE
+        );
+    }
+
+    /**
+     * Create the legacy data mapper factory.
+     *
+     * @return legacy_data_mapper_factory
+     */
+    public static function get_legacy_data_mapper_factory(): legacy_data_mapper_factory {
+        return new legacy_data_mapper_factory();
+    }
+
+    /**
+     * Create the exporter factory.
+     *
+     * @return exporter_factory
+     */
+    public static function get_exporter_factory(): exporter_factory {
+        return new exporter_factory(
+            self::get_legacy_data_mapper_factory(),
+            self::get_manager_factory(),
+            self::get_url_factory(),
+            self::get_vault_factory()
+        );
+    }
+
+    /**
+     * Create the vault factory.
+     *
+     * @return vault_factory
+     */
+    public static function get_vault_factory(): vault_factory {
+        global $DB;
+
+        return new vault_factory(
+            $DB,
+            self::get_entity_factory(),
+            get_file_storage(),
+            self::get_legacy_data_mapper_factory()
+        );
+    }
+
+    /**
+     * Create the manager factory.
+     *
+     * @return manager_factory
+     */
+    public static function get_manager_factory(): manager_factory {
+        return new manager_factory(
+            self::get_legacy_data_mapper_factory()
+        );
+    }
+
+    /**
+     * Create the entity factory.
+     *
+     * @return entity_factory
+     */
+    public static function get_entity_factory(): entity_factory {
+        return new entity_factory();
+    }
+
+    /**
+     * Create the builder factory.
+     *
+     * @return builder_factory
+     */
+    public static function get_builder_factory(): builder_factory {
+        global $PAGE;
+
+        return new builder_factory(
+            self::get_legacy_data_mapper_factory(),
+            self::get_exporter_factory(),
+            self::get_vault_factory(),
+            self::get_manager_factory(),
+            $PAGE->get_renderer('mod_forum')
+        );
+    }
+
+    /**
+     * Create the URL factory.
+     *
+     * @return url_factory
+     */
+    public static function get_url_factory(): url_factory {
+        return new url_factory(
+            self::get_legacy_data_mapper_factory()
+        );
+    }
+}

mod/forum/classes/local/data_mappers/legacy/author.php

@@ -0,0 +1,73 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Author data mapper.
+ *
+ * @package    mod_forum
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_forum\local\data_mappers\legacy;
+
+defined('MOODLE_INTERNAL') || die();
+
+use mod_forum\local\entities\author as author_entity;
+use stdClass;
+
+/**
+ * Convert an author entity into an stdClass.
+ *
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class author {
+    /**
+     * Convert a list of author entities into stdClasses.
+     *
+     * @param author_entity[] $authors The authors to convert.
+     * @return stdClass[]
+     */
+    public function to_legacy_objects(array $authors): array {
+        return array_map(function(author_entity $author) {
+            return (object) [
+                'id' => $author->get_id(),
+                'picture' => $author->get_picture_item_id(),
+                'firstname' => $author->get_first_name(),
+                'lastname' => $author->get_last_name(),
+                'fullname' => $author->get_full_name(),
+                'email' => $author->get_email(),
+                'deleted' => $author->is_deleted(),
+                'middlename' => $author->get_middle_name(),
+                'firstnamephonetic' => $author->get_first_name_phonetic(),
+                'lastnamephonetic' => $author->get_last_name_phonetic(),
+                'alternatename' => $author->get_alternate_name(),
+                'imagealt' => $author->get_image_alt()
+            ];
+        }, $authors);
+    }
+
+    /**
+     * Convert an author entity into an stdClass.
+     *
+     * @param author_entity $author The author to convert.
+     * @return stdClass
+     */
+    public function to_legacy_object(author_entity $author): stdClass {
+        return $this->to_legacy_objects([$author])[0];
+    }
+}

mod/forum/classes/local/data_mappers/legacy/discussion.php

@@ -0,0 +1,75 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Discussion data mapper.
+ *
+ * @package    mod_forum
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_forum\local\data_mappers\legacy;
+
+defined('MOODLE_INTERNAL') || die();
+
+use mod_forum\local\entities\discussion as discussion_entity;
+use stdClass;
+
+/**
+ * Convert a discussion entity into an stdClass.
+ *
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class discussion {
+    /**
+     * Convert a list of discussion entities into stdClasses.
+     *
+     * @param discussion_entity[] $authors The authors to convert.
+     * @return stdClass[]
+     */
+    public function to_legacy_objects(array $discussions): array {
+        return array_map(function(discussion_entity $discussion) {
+            return (object) [
+                'id' => $discussion->get_id(),
+                'course' => $discussion->get_course_id(),
+                'forum' => $discussion->get_forum_id(),
+                'name' => $discussion->get_name(),
+                'firstpost' => $discussion->get_first_post_id(),
+                'userid' => $discussion->get_user_id(),
+                'groupid' => $discussion->get_group_id(),
+                'assessed' => $discussion->is_assessed(),
+                'timemodified' => $discussion->get_time_modified(),
+                'usermodified' => $discussion->get_user_modified(),
+                'timestart' => $discussion->get_time_start(),
+                'timeend' => $discussion->get_time_end(),
+                'pinned' => $discussion->is_pinned(),
+                'timelocked' => $discussion->get_locked()
+            ];
+        }, $discussions);
+    }
+
+    /**
+     * Convert a discussion entity into an stdClass.
+     *
+     * @param discussion_entity $discussion The discussion to convert.
+     * @return stdClass
+     */
+    public function to_legacy_object(discussion_entity $discussion): stdClass {
+        return $this->to_legacy_objects([$discussion])[0];
+    }
+}

mod/forum/classes/local/data_mappers/legacy/forum.php

@@ -0,0 +1,90 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Forum data mapper.
+ *
+ * @package    mod_forum
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_forum\local\data_mappers\legacy;
+
+defined('MOODLE_INTERNAL') || die();
+
+use mod_forum\local\entities\forum as forum_entity;
+use stdClass;
+
+/**
+ * Convert a forum entity into an stdClass.
+ *
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class forum {
+    /**
+     * Convert a list of forum entities into stdClasses.
+     *
+     * @param forum_entity[] $forums The forums to convert.
+     * @return stdClass[]
+     */
+    public function to_legacy_objects(array $forums): array {
+        return array_map(function(forum_entity $forum) {
+            return (object) [
+                'id' => $forum->get_id(),
+                'course' => $forum->get_course_id(),
+                'type' => $forum->get_type(),
+                'name' => $forum->get_name(),
+                'intro' => $forum->get_intro(),
+                'introformat' => $forum->get_intro_format(),
+                'assessed' => $forum->get_rating_aggregate(),
+                'assesstimestart' => $forum->get_assess_time_start(),
+                'assesstimefinish' => $forum->get_assess_time_finish(),
+                'scale' => $forum->get_scale(),
+                'grade_forum' => $forum->get_grade_for_forum(),
+                'grade_forum_notify' => $forum->should_notify_students_default_when_grade_for_forum(),
+                'maxbytes' => $forum->get_max_bytes(),
+                'maxattachments' => $forum->get_max_attachments(),
+                'forcesubscribe' => $forum->get_subscription_mode(),
+                'trackingtype' => $forum->get_tracking_type(),
+                'rsstype' => $forum->get_rss_type(),
+                'rssarticles' => $forum->get_rss_articles(),
+                'timemodified' => $forum->get_time_modified(),
+                'warnafter' => $forum->get_warn_after(),
+                'blockafter' => $forum->get_block_after(),
+                'blockperiod' => $forum->get_block_period(),
+                'completiondiscussions' => $forum->get_completion_discussions(),
+                'completionreplies' => $forum->get_completion_replies(),
+                'completionposts' => $forum->get_completion_posts(),
+                'displaywordcount' => $forum->should_display_word_count(),
+                'lockdiscussionafter' => $forum->get_lock_discussions_after(),
+                'duedate' => $forum->get_due_date(),
+                'cutoffdate' => $forum->get_cutoff_date()
+            ];
+        }, $forums);
+    }
+
+    /**
+     * Convert a forum entity into an stdClass.
+     *
+     * @param forum_entity $forum The forum to convert.
+     * @return stdClass
+     */
+    public function to_legacy_object(forum_entity $forum): stdClass {
+        return $this->to_legacy_objects([$forum])[0];
+    }
+}

mod/forum/classes/local/data_mappers/legacy/post.php

@@ -0,0 +1,79 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Post data mapper.
+ *
+ * @package    mod_forum
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_forum\local\data_mappers\legacy;
+
+defined('MOODLE_INTERNAL') || die();
+
+use mod_forum\local\entities\post as post_entity;
+use stdClass;
+
+/**
+ * Convert a post entity into an stdClass.
+ *
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class post {
+    /**
+     * Convert a list of post entities into stdClasses.
+     *
+     * @param post_entity[] $posts The posts to convert.
+     * @return stdClass[]
+     */
+    public function to_legacy_objects(array $posts): array {
+        return array_map(function(post_entity $post) {
+            return (object) [
+                'id' => $post->get_id(),
+                'discussion' => $post->get_discussion_id(),
+                'parent' => $post->get_parent_id(),
+                'userid' => $post->get_author_id(),
+                'created' => $post->get_time_created(),
+                'modified' => $post->get_time_modified(),
+                'mailed' => $post->has_been_mailed(),
+                'subject' => $post->get_subject(),
+                'message' => $post->get_message(),
+                'messageformat' => $post->get_message_format(),
+                'messagetrust' => $post->is_message_trusted(),
+                'attachment' => $post->has_attachments(),
+                'totalscore' => $post->get_total_score(),
+                'mailnow' => $post->should_mail_now(),
+                'deleted' => $post->is_deleted(),
+                'privatereplyto' => $post->get_private_reply_recipient_id(),
+                'wordcount' => $post->get_wordcount(),
+                'charcount' => $post->get_charcount(),
+            ];
+        }, $posts);
+    }
+
+    /**
+     * Convert a post entity into an stdClass.
+     *
+     * @param post_entity $post The post to convert.
+     * @return stdClass
+     */
+    public function to_legacy_object(post_entity $post): stdClass {
+        return $this->to_legacy_objects([$post])[0];
+    }
+}

mod/forum/classes/local/entities/author.php

@@ -0,0 +1,211 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Author class.
+ *
+ * @package    mod_forum
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_forum\local\entities;
+
+defined('MOODLE_INTERNAL') || die();
+
+/**
+ * Author class.
+ *
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class author {
+    /** @var int $id ID */
+    private $id;
+    /** @var int $pictureitemid Picture item id */
+    private $pictureitemid;
+    /** @var string $firstname First name */
+    private $firstname;
+    /** @var string $lastname Last name */
+    private $lastname;
+    /** @var string $fullname Full name */
+    private $fullname;
+    /** @var string $email Email */
+    private $email;
+    /** @var bool $deleted Deleted */
+    private $deleted;
+    /** @var string $middlename Middle name */
+    private $middlename;
+    /** @var string $firstnamephonetic Phonetic spelling of first name */
+    private $firstnamephonetic;
+    /** @var string $lastnamephonetic Phonetic spelling of last name */
+    private $lastnamephonetic;
+    /** @var string $alternatename Altername name */
+    private $alternatename;
+    /** @var string $imagealt Image alt */
+    private $imagealt;
+
+    /**
+     * Constructor.
+     *
+     * @param int $id ID
+     * @param int $pictureitemid Picture item id
+     * @param string $firstname First name
+     * @param string $lastname Last name
+     * @param string $fullname Full name
+     * @param string $email Email
+     * @param string|null $middlename Middle name
+     * @param string|null $firstnamephonetic Phonetic spelling of first name
+     * @param string|null $lastnamephonetic Phonetic spelling of last name
+     * @param string|null $alternatename Altername name
+     * @param string|null $imagealt Image alt
+     */
+    public function __construct(
+        int $id,
+        int $pictureitemid,
+        string $firstname,
+        string $lastname,
+        string $fullname,
+        string $email,
+        bool $deleted,
+        string $middlename = null,
+        string $firstnamephonetic = null,
+        string $lastnamephonetic = null,
+        string $alternatename = null,
+        string $imagealt = null
+    ) {
+        $this->id = $id;
+        $this->pictureitemid = $pictureitemid;
+        $this->firstname = $firstname;
+        $this->lastname = $lastname;
+        $this->fullname = $fullname;
+        $this->email = $email;
+        $this->deleted = $deleted;
+        $this->middlename = $middlename;
+        $this->firstnamephonetic = $firstnamephonetic;
+        $this->lastnamephonetic = $lastnamephonetic;
+        $this->alternatename = $alternatename;
+        $this->imagealt = $imagealt;
+    }
+
+    /**
+     * Return the id.
+     *
+     * @return int
+     */
+    public function get_id(): int {
+        return $this->id;
+    }
+
+    /**
+     * Return the picture item id.
+     *
+     * @return int
+     */
+    public function get_picture_item_id(): int {
+        return $this->pictureitemid;
+    }
+
+    /**
+     * Return the first name.
+     *
+     * @return string
+     */
+    public function get_first_name(): string {
+        return $this->firstname;
+    }
+
+    /**
+     * Return the last name.
+     *
+     * @return string
+     */
+    public function get_last_name(): string {
+        return $this->lastname;
+    }
+
+    /**
+     * Return the full name.
+     *
+     * @return string
+     */
+    public function get_full_name(): string {
+        return $this->fullname;
+    }
+
+    /**
+     * Return the email.
+     *
+     * @return string
+     */
+    public function get_email(): string {
+        return $this->email;
+    }
+
+    /**
+     * Is the author deleted?
+     *
+     * @return bool
+     */
+    public function is_deleted(): bool {
+        return !empty($this->deleted);
+    }
+
+    /**
+     * Return the middle name.
+     *
+     * @return string|null
+     */
+    public function get_middle_name(): ?string {
+        return $this->middlename;
+    }
+
+    /**
+     * Return the first name phonetic.
+     *
+     * @return string|null
+     */
+    public function get_first_name_phonetic(): ?string {
+        return $this->firstnamephonetic;
+    }
+
+    /**
+     * Return the last name phonetic.
+     *
+     * @return string|null
+     */
+    public function get_last_name_phonetic(): ?string {
+        return $this->lastnamephonetic;
+    }
+
+    /**
+     * Return the alternate name.
+     *
+     * @return string|null
+     */
+    public function get_alternate_name(): ?string {
+        return $this->alternatename;
+    }
+
+    /**
+     * Return the image alt.
+     *
+     * @return string|null
+     */
+    public function get_image_alt(): ?string {
+        return $this->imagealt;
+    }
+}

mod/forum/classes/local/entities/discussion.php

@@ -0,0 +1,335 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Discussion class.
+ *
+ * @package    mod_forum
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_forum\local\entities;
+
+defined('MOODLE_INTERNAL') || die();
+
+use mod_forum\local\entities\post as post_entity;
+
+/**
+ * Discussion class.
+ *
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class discussion {
+    /** @var int $id ID */
+    private $id;
+    /** @var int $courseid Course id */
+    private $courseid;
+    /** @var int $forumid Forum id */
+    private $forumid;
+    /** @var string $name Discussion name */
+    private $name;
+    /** @var int $firstpostid Id of the first post in the discussion */
+    private $firstpostid;
+    /** @var int $userid Id of the user that created the discussion */
+    private $userid;
+    /** @var int $groupid Group id if it's a group dicussion */
+    private $groupid;
+    /** @var bool $assessed Is the discussion assessed? */
+    private $assessed;
+    /** @var int $timemodified Timestamp for last modification to the discussion */
+    private $timemodified;
+    /** @var int $usermodified Id of user that last modified the discussion */
+    private $usermodified;
+    /** @var int $timestart Start time for the discussion */
+    private $timestart;
+    /** @var int $timeend End time for the discussion */
+    private $timeend;
+    /** @var bool $pinned Is the discussion pinned? */
+    private $pinned;
+    /** @var int $locked The timestamp of when the discussion was locked */
+    private $timelocked;
+
+    /**
+     * Constructor.
+     *
+     * @param int $id ID
+     * @param int $courseid Course id
+     * @param int $forumid Forum id
+     * @param string $name Discussion name
+     * @param int $firstpostid Id of the first post in the discussion
+     * @param int $userid Id of the user that created the discussion
+     * @param int $groupid Group id if it's a group dicussion
+     * @param bool $assessed Is the discussion assessed?
+     * @param int $timemodified Timestamp for last modification to the discussion
+     * @param int $usermodified Id of user that last modified the discussion
+     * @param int $timestart Start time for the discussion
+     * @param int $timeend End time for the discussion
+     * @param bool $pinned Is the discussion pinned?
+     * @param int $locked Time this discussion was locked
+     */
+    public function __construct(
+        int $id,
+        int $courseid,
+        int $forumid,
+        string $name,
+        int $firstpostid,
+        int $userid,
+        int $groupid,
+        bool $assessed,
+        int $timemodified,
+        int $usermodified,
+        int $timestart,
+        int $timeend,
+        bool $pinned,
+        int $locked
+    ) {
+        $this->id = $id;
+        $this->courseid = $courseid;
+        $this->forumid = $forumid;
+        $this->name = $name;
+        $this->firstpostid = $firstpostid;
+        $this->userid = $userid;
+        $this->groupid = $groupid;
+        $this->assessed = $assessed;
+        $this->timemodified = $timemodified;
+        $this->usermodified = $usermodified;
+        $this->timestart = $timestart;
+        $this->timeend = $timeend;
+        $this->pinned = $pinned;
+        $this->timelocked = $locked;
+    }
+
+    /**
+     * Get the discussion id.
+     *
+     * @return int
+     */
+    public function get_id(): int {
+        return $this->id;
+    }
+
+    /**
+     * Get the course id.
+     *
+     * @return int
+     */
+    public function get_course_id(): int {
+        return $this->courseid;
+    }
+
+    /**
+     * Get the forum id.
+     *
+     * @return int
+     */
+    public function get_forum_id(): int {
+        return $this->forumid;
+    }
+
+    /**
+     * Get the name of the discussion.
+     *
+     * @return string
+     */
+    public function get_name(): string {
+        return $this->name;
+    }
+
+    /**
+     * Get the id of the fist post in the discussion.
+     *
+     * @return int
+     */
+    public function get_first_post_id(): int {
+        return $this->firstpostid;
+    }
+
+    /**
+     * Get the id of the user that created the discussion.
+     *
+     * @return int
+     */
+    public function get_user_id(): int {
+        return $this->userid;
+    }
+
+    /**
+     * Get the id of the group that this discussion belongs to.
+     *
+     * @return int
+     */
+    public function get_group_id(): int {
+        return $this->groupid;
+    }
+
+    /**
+     * Check if this discussion is assessed.
+     *
+     * @return bool
+     */
+    public function is_assessed(): bool {
+        return $this->assessed;
+    }
+
+    /**
+     * Get the timestamp for when this discussion was last modified.
+     *
+     * @return int
+     */
+    public function get_time_modified(): int {
+        return $this->timemodified;
+    }
+
+    /**
+     * Get the id of the user that last modified this discussion.
+     *
+     * @return int
+     */
+    public function get_user_modified(): int {
+        return $this->usermodified;
+    }
+
+    /**
+     * Get the start time of this discussion. Returns zero if the discussion
+     * has no designated start time.
+     *
+     * @return int
+     */
+    public function get_time_start(): int {
+        return $this->timestart;
+    }
+
+    /**
+     * Get the end time of this discussion. Returns zero if the discussion
+     * has no designated end time.
+     *
+     * @return int
+     */
+    public function get_time_end(): int {
+        return $this->timeend;
+    }
+
+    /**
+     * Check if this discussion is pinned.
+     *
+     * @return bool
+     */
+    public function is_pinned(): bool {
+        return $this->pinned;
+    }
+
+    /**
+     * Get the locked time of this discussion.
+     *
+     * @return bool
+     */
+    public function get_locked(): int {
+        return $this->timelocked;
+    }
+
+    /**
+     * Is this discussion locked based on it's locked attribute
+     *
+     * @return bool
+     */
+    public function is_locked(): bool {
+        return ($this->timelocked ? true : false);
+    }
+
+    /**
+     * Set the locked timestamp
+     *
+     * @param int $timestamp The value we want to store into 'locked'
+     */
+    public function toggle_locked_state(int $timestamp) {
+        // Check the current value against what we want the value to be i.e. '$timestamp'.
+        $this->timelocked = ($this->timelocked && $timestamp ? $this->timelocked : $timestamp);
+    }
+
+    /**
+     * Check if the given post is the first post in this discussion.
+     *
+     * @param post_entity $post The post to check
+     * @return bool
+     */
+    public function is_first_post(post_entity $post): bool {
+        return $this->get_first_post_id() === $post->get_id();
+    }
+
+    /**
+     * Check if the discussion has started yet. DEFAULTS: true if not set
+     *
+     * @return bool
+     */
+    public function has_started(): bool {
+        $startime = $this->get_time_start();
+        return empty($startime) || $startime < time();
+    }
+
+    /**
+     * Check if the discussion has ended. DEFAULTS: false if not set
+     *
+     * @return bool
+     */
+    public function has_ended(): bool {
+        $endtime = $this->get_time_end();
+        return !empty($endtime) && $endtime < time();
+    }
+
+    /**
+     * Check if the discussion belongs to a group.
+     *
+     * @return bool
+     */
+    public function has_group(): bool {
+        return $this->get_group_id() > 0;
+    }
+
+    /**
+     * Set the pinned value for this entity
+     *
+     * @param int $targetstate The state to change the pin to
+     * @return bool
+     */
+    public function set_pinned(int $targetstate): void {
+        if ($targetstate != $this->pinned) {
+            $this->pinned = $targetstate;
+        }
+    }
+
+    /**
+     * Check if the discussion is timed.
+     *
+     * @return bool
+     */
+    public function is_timed_discussion(): bool {
+        global $CFG;
+
+        return !empty($CFG->forum_enabletimedposts) &&
+              ($this->get_time_start() || $this->get_time_end());
+    }
+
+    /**
+     * Check if the timed discussion is visible.
+     *
+     * @return bool
+     */
+    public function is_timed_discussion_visible(): bool {
+        return !$this->is_timed_discussion() || ($this->has_started() && !$this->has_ended());
+    }
+}

mod/forum/classes/local/entities/discussion_summary.php

@@ -0,0 +1,104 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Discussion summary class.
+ *
+ * @package    mod_forum
+ * @copyright  2019 Andrew Nicols <andrew@nicols.co.uk>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_forum\local\entities;
+
+defined('MOODLE_INTERNAL') || die();
+
+use mod_forum\local\entities\discussion as discussion_entity;
+use mod_forum\local\entities\post as post_entity;
+use mod_forum\local\entities\author as author_entity;
+
+/**
+ * Discussion summary class.
+ *
+ * @copyright  2019 Andrew Nicols <andrew@nicols.co.uk>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class discussion_summary {
+    /** @var discussion_entity $discussion The discussion being summarised */
+    private $discussion;
+    /** @var author_entity $firstpostauthor Author of the first post in the discussion */
+    private $firstpostauthor;
+    /** @var post_entity $firstpost First post in the discussion */
+    private $firstpost;
+    /** @var author_entity $latestpostauthor Author of the last post in the discussion */
+    private $latestpostauthor;
+
+    /**
+     * Constructor.
+     *
+     * @param discussion_entity $discussion The discussion being summarised
+     * @param post_entity $firstpost First post in the discussion
+     * @param author_entity $firstpostauthor Author of the first post in the discussion
+     * @param author_entity $latestpostauthor Author of the last post in the discussion
+     */
+    public function __construct(
+        discussion_entity $discussion,
+        post_entity $firstpost,
+        author_entity $firstpostauthor,
+        author_entity $latestpostauthor
+    ) {
+        $this->discussion = $discussion;
+        $this->firstpostauthor = $firstpostauthor;
+        $this->firstpost = $firstpost;
+        $this->latestpostauthor = $latestpostauthor;
+    }
+
+    /**
+     * Get the discussion entity.
+     *
+     * @return discussion_entity
+     */
+    public function get_discussion(): discussion_entity {
+        return $this->discussion;
+    }
+
+    /**
+     * Get the author entity for the first post.
+     *
+     * @return author_entity
+     */
+    public function get_first_post_author(): author_entity {
+        return $this->firstpostauthor;
+    }
+
+    /**
+     * Get the author entity for the last post.
+     *
+     * @return author_entity
+     */
+    public function get_latest_post_author(): author_entity {
+        return $this->latestpostauthor;
+    }
+
+    /**
+     * Get the post entity for the first post.
+     *
+     * @return post_entity
+     */
+    public function get_first_post(): post_entity {
+        return $this->firstpost;
+    }
+}

mod/forum/classes/local/entities/forum.php

@@ -0,0 +1,672 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Forum class.
+ *
+ * @package    mod_forum
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_forum\local\entities;
+
+defined('MOODLE_INTERNAL') || die();
+
+global $CFG;
+require_once($CFG->dirroot . '/mod/forum/lib.php');
+require_once($CFG->dirroot . '/rating/lib.php');
+
+use mod_forum\local\entities\discussion as discussion_entity;
+use context;
+use stdClass;
+
+/**
+ * Forum class.
+ *
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class forum {
+    /** @var context $context The forum module context */
+    private $context;
+    /** @var stdClass $coursemodule The forum course module record */
+    private $coursemodule;
+    /** @var stdClass $course The forum course record */
+    private $course;
+    /** @var int $effectivegroupmode The effective group mode */
+    private $effectivegroupmode;
+    /** @var int $id ID */
+    private $id;
+    /** @var int $courseid Id of the course this forum is in */
+    private $courseid;
+    /** @var string $type The forum type, e.g. single, qanda, etc */
+    private $type;
+    /** @var string $name Name of the forum */
+    private $name;
+    /** @var string $intro Intro text */
+    private $intro;
+    /** @var int $introformat Format of the intro text */
+    private $introformat;
+    /** @var int $assessed The forum rating aggregate */
+    private $assessed;
+    /** @var int $assesstimestart Timestamp to begin assessment */
+    private $assesstimestart;
+    /** @var int $assesstimefinish Timestamp to end assessment */
+    private $assesstimefinish;
+    /** @var int $scale The rating scale */
+    private $scale;
+    /** @var int $gradeforum The grade for the forum when grading holistically */
+    private $gradeforum;
+    /** @var bool $gradeforumnotify Whether to notify students when the forum is graded holistically */
+    private $gradeforumnotify;
+    /** @var int $maxbytes Maximum attachment size */
+    private $maxbytes;
+    /** @var int $maxattachments Maximum number of attachments */
+    private $maxattachments;
+    /** @var int $forcesubscribe Does the forum force users to subscribe? */
+    private $forcesubscribe;
+    /** @var int $trackingtype Tracking type */
+    private $trackingtype;
+    /** @var int $rsstype RSS type */
+    private $rsstype;
+    /** @var int $rssarticles RSS articles */
+    private $rssarticles;
+    /** @var int $timemodified Timestamp when the forum was last modified */
+    private $timemodified;
+    /** @var int $warnafter Warn after */
+    private $warnafter;
+    /** @var int $blockafter Block after */
+    private $blockafter;
+    /** @var int $blockperiod Block period */
+    private $blockperiod;
+    /** @var int $completiondiscussions Completion discussions */
+    private $completiondiscussions;
+    /** @var int $completionreplies Completion replies */
+    private $completionreplies;
+    /** @var int $completionposts Completion posts */
+    private $completionposts;
+    /** @var bool $displaywordcount Should display word counts in posts */
+    private $displaywordcount;
+    /** @var bool $lockdiscussionafter Timestamp after which discussions should be locked */
+    private $lockdiscussionafter;
+    /** @var int $duedate Timestamp that represents the due date for forum posts */
+    private $duedate;
+    /** @var int $cutoffdate Timestamp after which forum posts will no longer be accepted */
+    private $cutoffdate;
+
+    /**
+     * Constructor
+     *
+     * @param context $context The forum module context
+     * @param stdClass $coursemodule The forum course module record
+     * @param stdClass $course The forum course record
+     * @param int $effectivegroupmode The effective group mode
+     * @param int $id ID
+     * @param int $courseid Id of the course this forum is in
+     * @param string $type The forum type, e.g. single, qanda, etc
+     * @param string $name Name of the forum
+     * @param string $intro Intro text
+     * @param int $introformat Format of the intro text
+     * @param int $assessed The forum rating aggregate
+     * @param int $assesstimestart Timestamp to begin assessment
+     * @param int $assesstimefinish Timestamp to end assessment
+     * @param int $scale The rating scale
+     * @param int $gradeforum The holistic grade
+     * @param bool $gradeforumnotify Default for whether to notify students when grade holistically
+     * @param int $maxbytes Maximum attachment size
+     * @param int $maxattachments Maximum number of attachments
+     * @param int $forcesubscribe Does the forum force users to subscribe?
+     * @param int $trackingtype Tracking type
+     * @param int $rsstype RSS type
+     * @param int $rssarticles RSS articles
+     * @param int $timemodified Timestamp when the forum was last modified
+     * @param int $warnafter Warn after
+     * @param int $blockafter Block after
+     * @param int $blockperiod Block period
+     * @param int $completiondiscussions Completion discussions
+     * @param int $completionreplies Completion replies
+     * @param int $completionposts Completion posts
+     * @param bool $displaywordcount Should display word counts in posts
+     * @param int $lockdiscussionafter Timestamp after which discussions should be locked
+     * @param int $duedate Timestamp that represents the due date for forum posts
+     * @param int $cutoffdate Timestamp after which forum posts will no longer be accepted
+     */
+    public function __construct(
+        context $context,
+        stdClass $coursemodule,
+        stdClass $course,
+        int $effectivegroupmode,
+        int $id,
+        int $courseid,
+        string $type,
+        string $name,
+        string $intro,
+        int $introformat,
+        int $assessed,
+        int $assesstimestart,
+        int $assesstimefinish,
+        int $scale,
+        int $gradeforum,
+        bool $gradeforumnotify,
+        int $maxbytes,
+        int $maxattachments,
+        int $forcesubscribe,
+        int $trackingtype,
+        int $rsstype,
+        int $rssarticles,
+        int $timemodified,
+        int $warnafter,
+        int $blockafter,
+        int $blockperiod,
+        int $completiondiscussions,
+        int $completionreplies,
+        int $completionposts,
+        bool $displaywordcount,
+        int $lockdiscussionafter,
+        int $duedate,
+        int $cutoffdate
+    ) {
+        $this->context = $context;
+        $this->coursemodule = $coursemodule;
+        $this->course = $course;
+        $this->effectivegroupmode = $effectivegroupmode;
+        $this->id = $id;
+        $this->courseid = $courseid;
+        $this->type = $type;
+        $this->name = $name;
+        $this->intro = $intro;
+        $this->introformat = $introformat;
+        $this->assessed = $assessed;
+        $this->assesstimestart = $assesstimestart;
+        $this->assesstimefinish = $assesstimefinish;
+        $this->scale = $scale;
+        $this->gradeforum = $gradeforum;
+        $this->gradeforumnotify = $gradeforumnotify;
+        $this->maxbytes = $maxbytes;
+        $this->maxattachments = $maxattachments;
+        $this->forcesubscribe = $forcesubscribe;
+        $this->trackingtype = $trackingtype;
+        $this->rsstype = $rsstype;
+        $this->rssarticles = $rssarticles;
+        $this->timemodified = $timemodified;
+        $this->warnafter = $warnafter;
+        $this->blockafter = $blockafter;
+        $this->blockperiod = $blockperiod;
+        $this->completiondiscussions = $completiondiscussions;
+        $this->completionreplies = $completionreplies;
+        $this->completionposts = $completionposts;
+        $this->displaywordcount = $displaywordcount;
+        $this->lockdiscussionafter = $lockdiscussionafter;
+        $this->duedate = $duedate;
+        $this->cutoffdate = $cutoffdate;
+    }
+
+    /**
+     * Get the forum module context.
+     *
+     * @return context
+     */
+    public function get_context(): context {
+        return $this->context;
+    }
+
+    /**
+     * Get the forum course module record
+     *
+     * @return stdClass
+     */
+    public function get_course_module_record(): stdClass {
+        return $this->coursemodule;
+    }
+
+    /**
+     * Get the effective group mode.
+     *
+     * @return int
+     */
+    public function get_effective_group_mode(): int {
+        return $this->effectivegroupmode;
+    }
+
+    /**
+     * Check if the forum is set to group mode.
+     *
+     * @return bool
+     */
+    public function is_in_group_mode(): bool {
+        return $this->get_effective_group_mode() !== NOGROUPS;
+    }
+
+    /**
+     * Get the course record.
+     *
+     * @return stdClass
+     */
+    public function get_course_record(): stdClass {
+        return $this->course;
+    }
+
+    /**
+     * Get the forum id.
+     *
+     * @return int
+     */
+    public function get_id(): int {
+        return $this->id;
+    }
+
+    /**
+     * Get the id of the course that the forum belongs to.
+     *
+     * @return int
+     */
+    public function get_course_id(): int {
+        return $this->courseid;
+    }
+
+    /**
+     * Get the forum type.
+     *
+     * @return string
+     */
+    public function get_type(): string {
+        return $this->type;
+    }
+
+    /**
+     * Get the forum name.
+     *
+     * @return string
+     */
+    public function get_name(): string {
+        return $this->name;
+    }
+
+    /**
+     * Get the forum intro text.
+     *
+     * @return string
+     */
+    public function get_intro(): string {
+        return $this->intro;
+    }
+
+    /**
+     * Get the forum intro text format.
+     *
+     * @return int
+     */
+    public function get_intro_format(): int {
+        return $this->introformat;
+    }
+
+    /**
+     * Get the rating aggregate.
+     *
+     * @return int
+     */
+    public function get_rating_aggregate(): int {
+        return $this->assessed;
+    }
+
+    /**
+     * Does the forum have a rating aggregate?
+     *
+     * @return bool
+     */
+    public function has_rating_aggregate(): bool {
+        return $this->get_rating_aggregate() != RATING_AGGREGATE_NONE;
+    }
+
+    /**
+     * Get the timestamp for when the assessment period begins.
+     *
+     * @return int
+     */
+    public function get_assess_time_start(): int {
+        return $this->assesstimestart;
+    }
+
+    /**
+     * Get the timestamp for when the assessment period ends.
+     *
+     * @return int
+     */
+    public function get_assess_time_finish(): int {
+        return $this->assesstimefinish;
+    }
+
+    /**
+     * Get the rating scale.
+     *
+     * @return int
+     */
+    public function get_scale(): int {
+        return $this->scale;
+    }
+
+    /**
+     * Get the grade for the forum when grading holistically.
+     *
+     * @return int
+     */
+    public function get_grade_for_forum(): int {
+        return $this->gradeforum;
+    }
+
+    /**
+     * Whether grading is enabled for this item.
+     *
+     * @return bool
+     */
+    public function is_grading_enabled(): bool {
+        return $this->get_grade_for_forum() !== 0;
+    }
+
+    /**
+     * Get the default for whether the students should be notified when grading holistically.
+     *
+     * @return bool
+     */
+    public function should_notify_students_default_when_grade_for_forum(): bool {
+        return $this->gradeforumnotify;
+    }
+
+    /**
+     * Get the maximum bytes.
+     *
+     * @return int
+     */
+    public function get_max_bytes(): int {
+        return $this->maxbytes;
+    }
+
+    /**
+     * Get the maximum number of attachments.
+     *
+     * @return int
+     */
+    public function get_max_attachments(): int {
+        return $this->maxattachments;
+    }
+
+    /**
+     * Get the subscription mode.
+     *
+     * @return int
+     */
+    public function get_subscription_mode(): int {
+        return $this->forcesubscribe;
+    }
+
+    /**
+     * Is the subscription mode set to optional.
+     *
+     * @return bool
+     */
+    public function is_subscription_optional(): bool {
+        return $this->get_subscription_mode() === FORUM_CHOOSESUBSCRIBE;
+    }
+
+    /**
+     * Is the subscription mode set to forced.
+     *
+     * @return bool
+     */
+    public function is_subscription_forced(): bool {
+        return $this->get_subscription_mode() === FORUM_FORCESUBSCRIBE;
+    }
+
+    /**
+     * Is the subscription mode set to automatic.
+     *
+     * @return bool
+     */
+    public function is_subscription_automatic(): bool {
+        return $this->get_subscription_mode() === FORUM_INITIALSUBSCRIBE;
+    }
+
+    /**
+     * Is the subscription mode set to disabled.
+     *
+     * @return bool
+     */
+    public function is_subscription_disabled(): bool {
+        return $this->get_subscription_mode() === FORUM_DISALLOWSUBSCRIBE;
+    }
+
+    /**
+     * Get the tracking type.
+     *
+     * @return int
+     */
+    public function get_tracking_type(): int {
+        return $this->trackingtype;
+    }
+
+    /**
+     * Get the RSS type.
+     *
+     * @return int
+     */
+    public function get_rss_type(): int {
+        return $this->rsstype;
+    }
+
+    /**
+     * Get the RSS articles.
+     *
+     * @return int
+     */
+    public function get_rss_articles(): int {
+        return $this->rssarticles;
+    }
+
+    /**
+     * Get the timestamp for when the forum was last modified.
+     *
+     * @return int
+     */
+    public function get_time_modified(): int {
+        return $this->timemodified;
+    }
+
+    /**
+     * Get warn after.
+     *
+     * @return int
+     */
+    public function get_warn_after(): int {
+        return $this->warnafter;
+    }
+
+    /**
+     * Get block after.
+     *
+     * @return int
+     */
+    public function get_block_after(): int {
+        return $this->blockafter;
+    }
+
+    /**
+     * Get the block period.
+     *
+     * @return int
+     */
+    public function get_block_period(): int {
+        return $this->blockperiod;
+    }
+
+    /**
+     * Does the forum have blocking enabled?
+     *
+     * @return bool
+     */
+    public function has_blocking_enabled(): bool {
+        return !empty($this->get_block_after()) && !empty($this->get_block_period());
+    }
+
+    /**
+     * Get the completion discussions.
+     *
+     * @return int
+     */
+    public function get_completion_discussions(): int {
+        return $this->completiondiscussions;
+    }
+
+    /**
+     * Get the completion replies.
+     *
+     * @return int
+     */
+    public function get_completion_replies(): int {
+        return $this->completionreplies;
+    }
+
+    /**
+     * Get the completion posts.
+     *
+     * @return int
+     */
+    public function get_completion_posts(): int {
+        return $this->completionposts;
+    }
+
+    /**
+     * Should the word counts be shown in the posts?
+     *
+     * @return bool
+     */
+    public function should_display_word_count(): bool {
+        return $this->displaywordcount;
+    }
+
+    /**
+     * Get the timestamp after which the discussion should be locked.
+     *
+     * @return int
+     */
+    public function get_lock_discussions_after(): int {
+        return $this->lockdiscussionafter;
+    }
+
+    /**
+     * Does the forum have a discussion locking timestamp?
+     *
+     * @return bool
+     */
+    public function has_lock_discussions_after(): bool {
+        return !empty($this->get_lock_discussions_after());
+    }
+
+    /**
+     * Check whether the discussion is locked based on forum's time based locking criteria
+     *
+     * @param discussion_entity $discussion
+     * @return bool
+     */
+    public function is_discussion_time_locked(discussion_entity $discussion): bool {
+        if (!$this->has_lock_discussions_after()) {
+            return false;
+        }
+
+        if ($this->get_type() === 'single') {
+            // It does not make sense to lock a single discussion forum.
+            return false;
+        }
+
+        return (($discussion->get_time_modified() + $this->get_lock_discussions_after()) < time());
+    }
+
+    /**
+     * Get the cutoff date.
+     *
+     * @return int
+     */
+    public function get_cutoff_date(): int {
+        return $this->cutoffdate;
+    }
+
+    /**
+     * Does the forum have a cutoff date?
+     *
+     * @return bool
+     */
+    public function has_cutoff_date(): bool {
+        return !empty($this->get_cutoff_date());
+    }
+
+    /**
+     * Is the cutoff date for the forum reached?
+     *
+     * @return bool
+     */
+    public function is_cutoff_date_reached(): bool {
+        if ($this->has_cutoff_date() && ($this->get_cutoff_date() < time())) {
+            return true;
+        }
+
+        return false;
+    }
+
+    /**
+     * Get the due date.
+     *
+     * @return int
+     */
+    public function get_due_date(): int {
+        return $this->duedate;
+    }
+
+    /**
+     * Does the forum have a due date?
+     *
+     * @return bool
+     */
+    public function has_due_date(): bool {
+        return !empty($this->get_due_date());
+    }
+
+    /**
+     * Is the due date for the forum reached?
+     *
+     * @return bool
+     */
+    public function is_due_date_reached(): bool {
+        if ($this->has_due_date() && ($this->get_due_date() < time())) {
+            return true;
+        }
+
+        return false;
+    }
+
+    /**
+     * Is the discussion locked? - Takes into account both discussion settings AND forum's criteria
+     *
+     * @param discussion_entity $discussion The discussion to check
+     * @return bool
+     */
+    public function is_discussion_locked(discussion_entity $discussion): bool {
+        if ($discussion->is_locked()) {
+            return true;
+        }
+
+        return $this->is_discussion_time_locked($discussion);
+    }
+}

mod/forum/classes/local/entities/post.php

@@ -0,0 +1,357 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Post class.
+ *
+ * @package    mod_forum
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_forum\local\entities;
+
+defined('MOODLE_INTERNAL') || die();
+
+use stdClass;
+
+/**
+ * Post class.
+ *
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class post {
+    /** @var int $id ID */
+    private $id;
+    /** @var int $discussionid The id of the discussion this post belongs to */
+    private $discussionid;
+    /** @var int $parentid The id of the post that this post is replying to. Zero if it isn't a reply. */
+    private $parentid;
+    /** @var int $authorid The id of user who authored the post */
+    private $authorid;
+    /** @var int $timecreated Timestamp for when the post was created */
+    private $timecreated;
+    /** @var int $timemodified Timestamp for when the post last modified */
+    private $timemodified;
+    /** @var bool $mailed If the post has been mailed */
+    private $mailed;
+    /** @var string $subject Post subject */
+    private $subject;
+    /** @var string $message Post message */
+    private $message;
+    /** @var int $messageformat Format of the post message */
+    private $messageformat;
+    /** @var bool $messagetrust Is this a trusted message, i.e. created by a trusted user. */
+    private $messagetrust;
+    /** @var bool $hasattachments Does the post have attachments */
+    private $hasattachments;
+    /** @var int $totalscore Total score */
+    private $totalscore;
+    /** @var bool $mailnow Should this post be mailed immediately */
+    private $mailnow;
+    /** @var bool $deleted Is the post deleted */
+    private $deleted;
+    /** @var int $privatereplyto The user being privately replied to */
+    private $privatereplyto;
+    /** @var int $wordcount Number of words in the message */
+    private $wordcount;
+    /** @var int $charcount Number of chars in the message */
+    private $charcount;
+
+    /**
+     * Constructor.
+     *
+     * @param int $id ID
+     * @param int $discussionid The id of the discussion this post belongs to
+     * @param int $parentid The id of the post that this post is replying to. Zero if it isn't a reply.
+     * @param int $authorid The id of user who authored the post
+     * @param int $timecreated Timestamp for when the post was created
+     * @param int $timemodified Timestamp for when the post last modified
+     * @param bool $mailed If the post has been mailed
+     * @param string $subject Post subject
+     * @param string $message Post message
+     * @param int $messageformat Format of the post message
+     * @param bool $messagetrust Is this a trusted message, i.e. created by a trusted user.
+     * @param bool $hasattachments Does the post have attachments
+     * @param int $totalscore Total score
+     * @param bool $mailnow Should this post be mailed immediately
+     * @param bool $deleted Is the post deleted
+     * @param int $privatereplyto Which user this reply is intended for in a private reply situation
+     */
+    public function __construct(
+        int $id,
+        int $discussionid,
+        int $parentid,
+        int $authorid,
+        int $timecreated,
+        int $timemodified,
+        bool $mailed,
+        string $subject,
+        string $message,
+        int $messageformat,
+        bool $messagetrust,
+        bool $hasattachments,
+        int $totalscore,
+        bool $mailnow,
+        bool $deleted,
+        int $privatereplyto,
+        ?int $wordcount,
+        ?int $charcount
+    ) {
+        $this->id = $id;
+        $this->discussionid = $discussionid;
+        $this->parentid = $parentid;
+        $this->authorid = $authorid;
+        $this->timecreated = $timecreated;
+        $this->timemodified = $timemodified;
+        $this->mailed = $mailed;
+        $this->subject = $subject;
+        $this->message = $message;
+        $this->messageformat = $messageformat;
+        $this->messagetrust = $messagetrust;
+        $this->hasattachments = $hasattachments;
+        $this->totalscore = $totalscore;
+        $this->mailnow = $mailnow;
+        $this->deleted = $deleted;
+        $this->privatereplyto = $privatereplyto;
+        $this->wordcount = $wordcount;
+        $this->charcount = $charcount;
+    }
+
+    /**
+     * Get the post id.
+     *
+     * @return int
+     */
+    public function get_id(): int {
+        return $this->id;
+    }
+
+    /**
+     * Get the discussion id.
+     *
+     * @return int
+     */
+    public function get_discussion_id(): int {
+        return $this->discussionid;
+    }
+
+    /**
+     * Get the id of the parent post. Returns zero if this post is not a reply.
+     *
+     * @return int
+     */
+    public function get_parent_id(): int {
+        return $this->parentid;
+    }
+
+    /**
+     * Does this post have a parent? I.e. is it a reply?
+     *
+     * @return bool
+     */
+    public function has_parent(): bool {
+        return $this->get_parent_id() > 0;
+    }
+
+    /**
+     * Get the id of the user that authored the post.
+     *
+     * @return int
+     */
+    public function get_author_id(): int {
+        return $this->authorid;
+    }
+
+    /**
+     * Get the timestamp for when this post was created.
+     *
+     * @return int
+     */
+    public function get_time_created(): int {
+        return $this->timecreated;
+    }
+
+    /**
+     * Get the timestamp for when this post was last modified.
+     *
+     * @return int
+     */
+    public function get_time_modified(): int {
+        return $this->timemodified;
+    }
+
+    /**
+     * Has this post been mailed?
+     *
+     * @return bool
+     */
+    public function has_been_mailed(): bool {
+        return $this->mailed;
+    }
+
+    /**
+     * Get the post subject.
+     *
+     * @return string
+     */
+    public function get_subject(): string {
+        return $this->subject;
+    }
+
+    /**
+     * Get the post message.
+     *
+     * @return string
+     */
+    public function get_message(): string {
+        return $this->message;
+    }
+
+    /**
+     * Get the post message format.
+     *
+     * @return int
+     */
+    public function get_message_format(): int {
+        return $this->messageformat;
+    }
+
+    /**
+     * Is this a trusted message? I.e. was it authored by a trusted user?
+     *
+     * @return bool
+     */
+    public function is_message_trusted(): bool {
+        return $this->messagetrust;
+    }
+
+    /**
+     * Does this post have attachments?
+     *
+     * @return bool
+     */
+    public function has_attachments(): bool {
+        return $this->hasattachments;
+    }
+
+    /**
+     * Get the total score.
+     *
+     * @return int
+     */
+    public function get_total_score(): int {
+        return $this->totalscore;
+    }
+
+    /**
+     * Should this post be mailed now?
+     *
+     * @return bool
+     */
+    public function should_mail_now(): bool {
+        return $this->mailnow;
+    }
+
+    /**
+     * Is this post deleted?
+     *
+     * @return bool
+     */
+    public function is_deleted(): bool {
+        return $this->deleted;
+    }
+
+    /**
+     * Is this post private?
+     *
+     * @return bool
+     */
+    public function is_private_reply(): bool {
+        return !empty($this->privatereplyto);
+    }
+
+    /**
+     * Get the id of the user that this post was intended for.
+     *
+     * @return int
+     */
+    public function get_private_reply_recipient_id(): int {
+        return $this->privatereplyto;
+    }
+
+
+    /**
+     * Get the post's age in seconds.
+     *
+     * @return int
+     */
+    public function get_age(): int {
+        return time() - $this->get_time_created();
+    }
+
+    /**
+     * Check if the given user authored this post.
+     *
+     * @param stdClass $user The user to check.
+     * @return bool
+     */
+    public function is_owned_by_user(stdClass $user): bool {
+        return $this->get_author_id() == $user->id;
+    }
+
+    /**
+     * Check if the given post is a private reply intended for the given user.
+     *
+     * @param stdClass $user The user to check.
+     * @return bool
+     */
+    public function is_private_reply_intended_for_user(stdClass $user): bool {
+        return $this->get_private_reply_recipient_id() == $user->id;
+    }
+
+    /**
+     * Returns the word count.
+     *
+     * @return int|null
+     */
+    public function get_wordcount(): ?int {
+        return $this->wordcount;
+    }
+
+    /**
+     * Returns the char count.
+     *
+     * @return int|null
+     */
+    public function get_charcount(): ?int {
+        return $this->charcount;
+    }
+
+    /**
+     * This methods adds/updates forum posts' word count and char count attributes based on $data->message.
+     *
+     * @param \stdClass $record A record ready to be inserted / updated in DB.
+     * @return void.
+     */
+    public static function add_message_counts(\stdClass $record): void {
+        if (!empty($record->message)) {
+            $record->wordcount = count_words($record->message, $record->messageformat);
+            $record->charcount = count_letters($record->message, $record->messageformat);
+        }
+    }
+}

mod/forum/classes/local/entities/post_read_receipt_collection.php

@@ -0,0 +1,86 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Post read receipt collection class.
+ *
+ * @package    mod_forum
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_forum\local\entities;
+
+defined('MOODLE_INTERNAL') || die();
+
+use mod_forum\local\entities\post as post_entity;
+use stdClass;
+
+/**
+ * Post read receipt collection class.
+ *
+ * Contains the list of read receipts for posts.
+ *
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class post_read_receipt_collection {
+    /** @var stdClass[] $receiptsbypostid Receipt records indexed by post id */
+    private $receiptsbypostid = [];
+
+    /**
+     * Constructor.
+     *
+     * @param array $records The list of post read receipt records.
+     */
+    public function __construct(array $records) {
+        foreach ($records as $record) {
+            $postid = $record->postid;
+
+            if (isset($this->receiptsbypostid[$postid])) {
+                $this->receiptsbypostid[$postid][] = $record;
+            } else {
+                $this->receiptsbypostid[$postid] = [$record];
+            }
+        }
+    }
+
+    /**
+     * Check whether a user has read a post.
+     *
+     * @param stdClass $user The user to check
+     * @param post_entity $post The post to check
+     * @return bool
+     */
+    public function has_user_read_post(stdClass $user, post_entity $post): bool {
+        global $CFG;
+        $isoldpost = ($post->get_time_modified() < (time() - ($CFG->forum_oldpostdays * 24 * 3600)));
+
+        if ($isoldpost) {
+            return true;
+        }
+
+        $receipts = isset($this->receiptsbypostid[$post->get_id()]) ? $this->receiptsbypostid[$post->get_id()] : [];
+
+        foreach ($receipts as $receipt) {
+            if ($receipt->userid == $user->id) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+}

mod/forum/classes/local/entities/sorter.php

@@ -0,0 +1,152 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Class to sort items.
+ *
+ * @package    mod_forum
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_forum\local\entities;
+
+defined('MOODLE_INTERNAL') || die();
+
+/**
+ * Class to sort lists of items.
+ *
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class sorter {
+    /** @var callable $getid Function used to get the id from an item */
+    private $getid;
+    /** @var callable $getparentid Function used to get the parent id from an item */
+    private $getparentid;
+
+    /**
+     * Constructor.
+     *
+     * Allows the calling code to provide 2 functions to get the id and parent id from
+     * the list of items it is intended to process.
+     *
+     * This allows this class to be composed in numerous different ways to support various
+     * types of items while keeping the underlying sorting algorithm consistent.
+     *
+     * @param callable $getid Function used to get the id from an item
+     * @param callable $getparentid Function used to get the parent id from an item
+     */
+    public function __construct(callable $getid, callable $getparentid) {
+        $this->getid = $getid;
+        $this->getparentid = $getparentid;
+    }
+
+    /**
+     * Sort a list of items into a parent/child data structure. The resulting data structure
+     * is a recursive array of arrays where the first element is the parent and the second is
+     * an array of it's children.
+     *
+     * For example
+     * If we have an array of items A, B, C, and D where D is a child of C, B and C are children
+     * of A.
+     *
+     * This function would sort them into the following:
+     * [
+     *      [
+     *          A,
+     *          [
+     *              [
+     *                  B,
+     *                  []
+     *              ],
+     *              [
+     *                  C,
+     *                  [
+     *                      [
+     *                          D,
+     *                          []
+     *                      ]
+     *                  ]
+     *              ]
+     *          ]
+     *      ]
+     * ]
+     *
+     * @param array $items The list of items to sort.
+     * @return array
+     */
+    public function sort_into_children(array $items): array {
+        $ids = array_reduce($items, function($carry, $item) {
+            $carry[($this->getid)($item)] = true;
+            return $carry;
+        }, []);
+
+        // Split out the items into "parents" and "replies" (children). These are unsorted
+        // at this point.
+        [$parents, $replies] = array_reduce($items, function($carry, $item) use ($ids) {
+            $parentid = ($this->getparentid)($item);
+
+            if (!empty($ids[$parentid])) {
+                // This is a child to another item in the list so add it to the children list.
+                $carry[1][] = $item;
+            } else {
+                // This isn't a child to anything in our list so it's a parent.
+                $carry[0][] = $item;
+            }
+
+            return $carry;
+        }, [[], []]);
+
+        if (empty($replies)) {
+            return array_map(function($parent) {
+                return [$parent, []];
+            }, $parents);
+        }
+
+        // Recurse to sort the replies into the correct nesting.
+        $sortedreplies = $this->sort_into_children($replies);
+
+        // Sort the parents and sorted replies into their matching pairs.
+        return array_map(function($parent) use ($sortedreplies) {
+            $parentid = ($this->getid)($parent);
+            return [
+                $parent,
+                array_values(array_filter($sortedreplies, function($replydata) use ($parentid) {
+                    return ($this->getparentid)($replydata[0]) == $parentid;
+                }))
+            ];
+        }, $parents);
+    }
+
+    /**
+     * Take the data structure returned from "sort_into_children" and flatten it back
+     * into an array. It does a depth first flatten which maintains the reply ordering.
+     *
+     * @param array $items Items in the data structure returned by "sort_into_children"
+     * @return array A flat array.
+     */
+    public function flatten_children(array $items): array {
+        $result = [];
+
+        foreach ($items as [$item, $children]) {
+            $result[] = $item;
+            $result = array_merge($result, $this->flatten_children($children));
+        }
+
+        return $result;
+    }
+}

mod/forum/classes/local/exporters/author.php

@@ -0,0 +1,222 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Author exporter.
+ *
+ * @package    mod_forum
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_forum\local\exporters;
+
+defined('MOODLE_INTERNAL') || die();
+
+use mod_forum\local\entities\author as author_entity;
+use mod_forum\local\exporters\group as group_exporter;
+use core\external\exporter;
+use renderer_base;
+
+require_once($CFG->dirroot . '/mod/forum/lib.php');
+
+/**
+ * Author exporter.
+ *
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class author extends exporter {
+    /** @var author_entity $author Author entity */
+    private $author;
+    /** @var int|null $authorcontextid The context id for the author entity */
+    private $authorcontextid;
+    /** @var array $authorgroups List of groups that the author belongs to */
+    private $authorgroups;
+    /** @var bool $canview Should the author be anonymised? */
+    private $canview;
+
+    /**
+     * Constructor.
+     *
+     * @param author_entity $author The author entity to export
+     * @param int|null $authorcontextid The context id for the author entity to export (null if the user doesn't have one)
+     * @param stdClass[] $authorgroups The list of groups that the author belongs to
+     * @param bool $canview Can the requesting user view this author or should it be anonymised?
+     * @param array $related The related data for the export.
+     */
+    public function __construct(
+        author_entity $author,
+        ?int $authorcontextid,
+        array $authorgroups = [],
+        bool $canview = true,
+        array $related = []
+    ) {
+        $this->author = $author;
+        $this->authorcontextid = $authorcontextid;
+        $this->authorgroups = $authorgroups;
+        $this->canview = $canview;
+        return parent::__construct([], $related);
+    }
+
+    /**
+     * Return the list of additional properties.
+     *
+     * @return array
+     */
+    protected static function define_other_properties() {
+        return [
+            'id' => [
+                'type' => PARAM_INT,
+                'optional' => true,
+                'default' => null,
+                'null' => NULL_ALLOWED
+            ],
+            'fullname' => [
+                'type' => PARAM_TEXT,
+                'optional' => true,
+                'default' => null,
+                'null' => NULL_ALLOWED
+            ],
+            'isdeleted' => [
+                'type' => PARAM_BOOL,
+                'optional' => true,
+                'default' => null,
+                'null' => NULL_ALLOWED
+            ],
+            'groups' => [
+                'multiple' => true,
+                'optional' => true,
+                'type' => [
+                    'id' => ['type' => PARAM_INT],
+                    'name' => ['type' => PARAM_TEXT],
+                    'urls' => [
+                        'type' => [
+                            'image' => [
+                                'type' => PARAM_URL,
+                                'optional' => true,
+                                'default' => null,
+                                'null' => NULL_ALLOWED
+                            ]
+                        ]
+                    ]
+                ]
+            ],
+            'urls' => [
+                'type' => [
+                    'profile' => [
+                        'description' => 'The URL for the use profile page',
+                        'type' => PARAM_URL,
+                        'optional' => true,
+                        'default' => null,
+                        'null' => NULL_ALLOWED
+                    ],
+                    'profileimage' => [
+                        'description' => 'The URL for the use profile image',
+                        'type' => PARAM_URL,
+                        'optional' => true,
+                        'default' => null,
+                        'null' => NULL_ALLOWED
+                    ],
+                ]
+            ]
+        ];
+    }
+
+    /**
+     * Get the additional values to inject while exporting.
+     *
+     * @param renderer_base $output The renderer.
+     * @return array Keys are the property names, values are their values.
+     */
+    protected function get_other_values(renderer_base $output) {
+        $author = $this->author;
+        $authorcontextid = $this->authorcontextid;
+        $urlfactory = $this->related['urlfactory'];
+        $context = $this->related['context'];
+        $forum = $this->related['forum'];
+
+        if ($this->canview) {
+            if ($author->is_deleted()) {
+                return [
+                    'id' => $author->get_id(),
+                    'fullname' => get_string('deleteduser', 'mod_forum'),
+                    'isdeleted' => true,
+                    'groups' => [],
+                    'urls' => [
+                        'profile' => ($urlfactory->get_author_profile_url($author, $forum->get_course_id()))->out(false),
+                        'profileimage' => ($urlfactory->get_author_profile_image_url($author, $authorcontextid))->out(false)
+                    ]
+                ];
+            } else {
+                $groups = array_map(function($group) use ($urlfactory, $context, $output) {
+                    $groupurl = null;
+                    $imageurl = get_group_picture_url($group, $group->courseid, true);
+
+                    if (course_can_view_participants($context)) {
+                        $groupurl = $urlfactory->get_author_group_url($group);
+                    }
+
+                    return [
+                        'id' => $group->id,
+                        'name' => format_string($group->name, true, ['context' => $context]),
+                        'urls' => [
+                            'image' => $imageurl ? $imageurl->out(false) : null,
+                            'group' => $groupurl ? $groupurl->out(false) : null
+
+                        ]
+                    ];
+                }, $this->authorgroups);
+
+                return [
+                    'id' => $author->get_id(),
+                    'fullname' => $author->get_full_name(),
+                    'isdeleted' => false,
+                    'groups' => $groups,
+                    'urls' => [
+                        'profile' => ($urlfactory->get_author_profile_url($author, $forum->get_course_id()))->out(false),
+                        'profileimage' => ($urlfactory->get_author_profile_image_url($author, $authorcontextid))->out(false)
+                    ]
+                ];
+            }
+        } else {
+            // The author should be anonymised.
+            return [
+                'id' => null,
+                'fullname' => get_string('forumauthorhidden', 'mod_forum'),
+                'isdeleted' => null,
+                'groups' => [],
+                'urls' => [
+                    'profile' => null,
+                    'profileimage' => null
+                ]
+            ];
+        }
+    }
+
+    /**
+     * Returns a list of objects that are related.
+     *
+     * @return array
+     */
+    protected static function define_related() {
+        return [
+            'urlfactory' => 'mod_forum\local\factories\url',
+            'context' => 'context',
+            'forum' => 'mod_forum\local\entities\forum',
+        ];
+    }
+}

mod/forum/classes/local/exporters/discussion.php

@@ -0,0 +1,286 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Discussion exporter class.
+ *
+ * @package    mod_forum
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_forum\local\exporters;
+
+defined('MOODLE_INTERNAL') || die();
+
+use mod_forum\local\entities\discussion as discussion_entity;
+use mod_forum\local\exporters\post as post_exporter;
+use mod_forum\local\factories\exporter as exporter_factory;
+use core\external\exporter;
+use renderer_base;
+
+/**
+ * Discussion exporter class.
+ *
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class discussion extends exporter {
+    /** @var discussion_entity $discussion Discussion to export */
+    private $discussion;
+
+    /**
+     * Constructor.
+     *
+     * @param discussion_entity $discussion Discussion to export
+     * @param array $related The related export data
+     */
+    public function __construct(discussion_entity $discussion, array $related = []) {
+        $this->discussion = $discussion;
+
+        return parent::__construct([], $related);
+    }
+
+    /**
+     * Return the list of additional properties.
+     *
+     * @return array
+     */
+    protected static function define_other_properties() {
+        return [
+            'id' => ['type' => PARAM_INT],
+            'forumid' => ['type' => PARAM_INT],
+            'pinned' => ['type' => PARAM_BOOL],
+            'locked' => ['type' => PARAM_BOOL],
+            'istimelocked' => ['type' => PARAM_BOOL],
+            'name' => ['type' => PARAM_TEXT],
+            'firstpostid' => ['type' => PARAM_INT],
+            'group' => [
+                'optional' => true,
+                'type' => [
+                    'name' => ['type' => PARAM_TEXT],
+                    'urls' => [
+                        'type' => [
+                            'picture' => [
+                                'optional' => true,
+                                'type' => PARAM_URL,
+                            ],
+                            'userlist' => [
+                                'optional' => true,
+                                'type' => PARAM_URL,
+                            ],
+                        ],
+                    ],
+                ],
+            ],
+            'times' => [
+                'type' => [
+                    'modified' => ['type' => PARAM_INT],
+                    'start' => ['type' => PARAM_INT],
+                    'end' => ['type' => PARAM_INT],
+                    'locked' => ['type' => PARAM_INT],
+                ],
+            ],
+            'userstate' => [
+                'type' => [
+                    'subscribed' => ['type' => PARAM_BOOL],
+                    'favourited' => ['type' => PARAM_BOOL],
+                ],
+            ],
+            'capabilities' => [
+                'type' => [
+                    'subscribe' => ['type' => PARAM_BOOL],
+                    'move' => ['type' => PARAM_BOOL],
+                    'pin' => ['type' => PARAM_BOOL],
+                    'post' => ['type' => PARAM_BOOL],
+                    'manage' => ['type' => PARAM_BOOL],
+                    'favourite' => ['type' => PARAM_BOOL]
+                ]
+            ],
+            'urls' => [
+                'type' => [
+                    'view' => ['type' => PARAM_URL],
+                    'viewlatest' => [
+                        'optional' => true,
+                        'type' => PARAM_URL
+                    ],
+                    'viewfirstunread' => [
+                        'optional' => true,
+                        'type' => PARAM_URL,
+                    ],
+                    'markasread' => ['type' => PARAM_URL],
+                    'subscribe' => ['type' => PARAM_URL],
+                    'pin' => [
+                        'optional' => true,
+                        'type' => PARAM_URL,
+                    ],
+                ],
+            ],
+            'timed' => [
+                'type' => [
+                    'istimed' => [
+                        'type' => PARAM_BOOL,
+                        'optional' => true,
+                        'default' => null,
+                        'null' => NULL_ALLOWED
+                    ],
+                    'visible' => [
+                        'type' => PARAM_BOOL,
+                        'optional' => true,
+                        'default' => null,
+                        'null' => NULL_ALLOWED
+                    ]
+                ]
+            ]
+        ];
+    }
+
+    /**
+     * Get the additional values to inject while exporting.
+     *
+     * @param renderer_base $output The renderer.
+     * @return array Keys are the property names, values are their values.
+     */
+    protected function get_other_values(renderer_base $output) {
+
+        $capabilitymanager = $this->related['capabilitymanager'];
+        $urlfactory = $this->related['urlfactory'];
+        $favouriteids = isset($this->related['favouriteids']) ? $this->related['favouriteids'] : [];
+
+        $forum = $this->related['forum'];
+        $forumrecord = $this->get_forum_record();
+        $user = $this->related['user'];
+        $discussion = $this->discussion;
+
+        $groupdata = null;
+        if ($discussion->has_group()) {
+            $groupsbyid = $this->related['groupsbyid'];
+            $group = $groupsbyid[$discussion->get_group_id()] ?? null;
+
+            // We may not have received the group if the caller doesn't want to include it in the export
+            // or if it's been deleted and the discussion record hasn't been updated.
+            if ($group) {
+                $groupdata = [
+                    'name' => format_string($group->name, true, ['context' => $this->related['context']]),
+                    'urls' => [],
+                ];
+
+                // If not hiding the group picture, and the group has a picture then use it. Fallback to generic group image.
+                if ($url = get_group_picture_url($group, $forum->get_course_id(), true)) {
+
+                    $groupdata['urls']['picture'] = $url;
+                } else {
+                    $groupdata['urls']['picture'] = $output->image_url('g/g1')->out(false);
+                }
+
+                if ($capabilitymanager->can_view_participants($user, $discussion)) {
+                    $groupdata['urls']['userlist'] = (new \moodle_url('/user/index.php', [
+                        'id' => $forum->get_course_id(),
+                        'group' => $group->id,
+                    ]));
+                }
+            }
+        }
+
+        $viewfirstunreadurl = $urlfactory->get_discussion_view_first_unread_post_url_from_discussion($discussion);
+        $data = [
+            'id' => $discussion->get_id(),
+            'forumid' => $forum->get_id(),
+            'pinned' => $discussion->is_pinned(),
+            'locked' => $forum->is_discussion_locked($discussion),
+            'istimelocked' => $forum->is_discussion_time_locked($discussion),
+            'name' => format_string($discussion->get_name(), true, [
+                'context' => $this->related['context']
+            ]),
+            'firstpostid' => $discussion->get_first_post_id(),
+            'times' => [
+                'modified' => $discussion->get_time_modified(),
+                'start' => $discussion->get_time_start(),
+                'end' => $discussion->get_time_end(),
+                'locked' => $discussion->get_locked()
+            ],
+            'userstate' => [
+                'subscribed' => \mod_forum\subscriptions::is_subscribed($user->id, $forumrecord, $discussion->get_id()),
+                'favourited' => in_array($discussion->get_id(), $favouriteids) ? true : false,
+            ],
+            'capabilities' => [
+                'subscribe' => $capabilitymanager->can_subscribe_to_discussion($user, $discussion),
+                'move' => $capabilitymanager->can_move_discussion($user, $discussion),
+                'pin' => $capabilitymanager->can_pin_discussion($user, $discussion),
+                'post' => $capabilitymanager->can_post_in_discussion($user, $discussion),
+                'manage' => $capabilitymanager->can_manage_forum($user),
+                'favourite' => $capabilitymanager->can_favourite_discussion($user) // Defaulting to true until we get capabilities sorted
+            ],
+            'urls' => [
+                'view' => $urlfactory->get_discussion_view_url_from_discussion($discussion)->out(false),
+                'viewfirstunread' => $viewfirstunreadurl->out(false),
+                'markasread' => $urlfactory->get_mark_discussion_as_read_url_from_discussion($forum, $discussion)->out(false),
+                'subscribe' => $urlfactory->get_discussion_subscribe_url($discussion)->out(false)
+            ]
+        ];
+
+        if (!empty($this->related['latestpostid'])) {
+            $data['urls']['viewlatest'] = $urlfactory->get_discussion_view_latest_post_url_from_discussion(
+                    $discussion,
+                    $this->related['latestpostid']
+                )->out(false);
+        }
+
+        if ($capabilitymanager->can_pin_discussions($user)) {
+            $data['urls']['pin'] = $urlfactory->get_pin_discussion_url_from_discussion($discussion)->out(false);
+        }
+
+        if ($groupdata) {
+            $data['group'] = $groupdata;
+        }
+
+        $canviewhiddentimedposts = $capabilitymanager->can_view_hidden_posts($user);
+        $canalwaysseetimedpost = $user->id == $discussion->get_user_id() || $canviewhiddentimedposts;
+        $data['timed']['istimed'] = $canalwaysseetimedpost ? $discussion->is_timed_discussion() : null;
+        $data['timed']['visible'] = $canalwaysseetimedpost ? $discussion->is_timed_discussion_visible() : null;
+
+        return $data;
+    }
+
+    /**
+     * Get the legacy forum record from the forum entity.
+     *
+     * @return stdClass
+     */
+    private function get_forum_record() {
+        $forumdbdatamapper = $this->related['legacydatamapperfactory']->get_forum_data_mapper();
+        return $forumdbdatamapper->to_legacy_object($this->related['forum']);
+    }
+
+    /**
+     * Returns a list of objects that are related.
+     *
+     * @return array
+     */
+    protected static function define_related() {
+        return [
+            'legacydatamapperfactory' => 'mod_forum\local\factories\legacy_data_mapper',
+            'context' => 'context',
+            'forum' => 'mod_forum\local\entities\forum',
+            'capabilitymanager' => 'mod_forum\local\managers\capability',
+            'urlfactory' => 'mod_forum\local\factories\url',
+            'user' => 'stdClass',
+            'groupsbyid' => 'stdClass[]',
+            'latestpostid' => 'int?',
+            'favouriteids' => 'int[]?'
+        ];
+    }
+}

mod/forum/classes/local/exporters/discussion_summaries.php

@@ -0,0 +1,170 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Discussion summaries exporter.
+ *
+ * @package     mod_forum
+ * @copyright   2019 Andrew Nicols <andrew@nicols.co.uk>
+ * @license     http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_forum\local\exporters;
+
+defined('MOODLE_INTERNAL') || die();
+
+use mod_forum\local\entities\discussion as discussion_entity;
+use mod_forum\local\exporters\post as post_exporter;
+use core\external\exporter;
+use renderer_base;
+
+/**
+ * Discussion summaries exporter.
+ *
+ * @copyright   2019 Andrew Nicols <andrew@nicols.co.uk>
+ * @license     http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class discussion_summaries extends exporter {
+    /** @var discussion_summary_entity[] The list of discussion summaries to export */
+    private $discussions;
+
+    /** @var stdClass[] The group information for each author */
+    private $groupsbyid;
+
+    /** @var stdClass[] The group information for each author */
+    private $groupsbyauthorid;
+
+    /** @var int[] Discussion reply counts indexed by dicussion id */
+    private $discussionreplycount;
+
+    /** @var int[] Discussion unread counts indexed by dicussion id */
+    private $discussionunreadcount;
+
+    /** @var array The latest post in each discussion */
+    private $latestpostids;
+
+    /** @var int[] The context ids for the first and latest post authors (indexed by author id) */
+    private $postauthorcontextids;
+
+    /**
+     * Constructor.
+     *
+     * @param discussion_summary_entity[] $discussion The list of discussion summaries to export
+     * @param stdClass[] $groupsbyid The group information for each author
+     * @param stdClass[] $groupsbyauthorid The group information for each author
+     * @param int[] $discussionreplycount Discussion reply counts indexed by dicussion id
+     * @param int[] $discussionunreadcount Discussion unread counts indexed by dicussion id
+     * @param int[] $latestpostids List of latest post ids indexed by discussion id
+     * @param int[] $postauthorcontextids The context ids for the first and latest post authors (indexed by author id)
+     * @param array $related The related
+     */
+    public function __construct(
+        array $discussions,
+        array $groupsbyid,
+        array $groupsbyauthorid,
+        array $discussionreplycount,
+        array $discussionunreadcount,
+        array $latestpostids,
+        array $postauthorcontextids,
+        array $related = []
+    ) {
+        $this->discussions = $discussions;
+        $this->groupsbyid = $groupsbyid;
+        $this->groupsbyauthorid = $groupsbyauthorid;
+        $this->discussionreplycount = $discussionreplycount;
+        $this->discussionunreadcount = $discussionunreadcount;
+        $this->latestpostids = $latestpostids;
+        $this->postauthorcontextids = $postauthorcontextids;
+        return parent::__construct([], $related);
+    }
+
+    /**
+     * Return the list of additional properties.
+     *
+     * @return array
+     */
+    protected static function define_other_properties() {
+        return [
+            'summaries' => [
+                'type' => discussion_summary::read_properties_definition(),
+                'multiple' => true
+            ],
+            'state' => [
+                'type' => [
+                    'hasdiscussions' => ['type' => PARAM_BOOL],
+                ],
+            ],
+        ];
+    }
+
+    /**
+     * Get the additional values to inject while exporting.
+     *
+     * @param renderer_base $output The renderer.
+     * @return array Keys are the property names, values are their values.
+     */
+    protected function get_other_values(renderer_base $output) {
+        $exporteddiscussions = [];
+        $related = $this->related;
+        $latestauthors = $this->related['latestauthors'];
+
+        foreach ($this->discussions as $discussion) {
+            $discussionid = $discussion->get_discussion()->get_id();
+            $replycount = isset($this->discussionreplycount[$discussionid]) ? $this->discussionreplycount[$discussionid] : 0;
+            $unreadcount = isset($this->discussionunreadcount[$discussionid]) ? $this->discussionunreadcount[$discussionid] : 0;
+            $latestpostid = isset($this->latestpostids[$discussionid]) ? $this->latestpostids[$discussionid] : 0;
+            $latestauthor = $latestauthors[$discussionid] ?? null;
+            $related['latestauthor'] = $latestauthor;
+            $exporter = new discussion_summary(
+                    $discussion,
+                    $this->groupsbyid,
+                    $this->groupsbyauthorid,
+                    $replycount,
+                    $unreadcount,
+                    $latestpostid,
+                    $this->postauthorcontextids[$discussion->get_first_post_author()->get_id()],
+                    $this->postauthorcontextids[$latestauthor->get_id()],
+                    $related
+                );
+            $exporteddiscussions[] = $exporter->export($output);
+        }
+
+        return [
+            'summaries' => $exporteddiscussions,
+            'state' => [
+                'hasdiscussions' => !empty($exporteddiscussions),
+            ],
+        ];
+    }
+
+    /**
+     * Returns a list of objects that are related.
+     *
+     * @return array
+     */
+    protected static function define_related() {
+        return [
+            'legacydatamapperfactory' => 'mod_forum\local\factories\legacy_data_mapper',
+            'context' => 'context',
+            'forum' => 'mod_forum\local\entities\forum',
+            'capabilitymanager' => 'mod_forum\local\managers\capability',
+            'urlfactory' => 'mod_forum\local\factories\url',
+            'user' => 'stdClass',
+            'favouriteids' => 'int[]?',
+            'latestauthors' => 'mod_forum\local\entities\author[]?'
+        ];
+    }
+}

mod/forum/classes/local/exporters/discussion_summary.php

@@ -0,0 +1,198 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Discussion summary exporter class.
+ *
+ * @package    mod_forum
+ * @copyright  2019 Andrew Nicols <andrew@nicols.co.uk>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_forum\local\exporters;
+
+defined('MOODLE_INTERNAL') || die();
+
+use mod_forum\local\entities\discussion_summary as discussion_summary_entity;
+use core\external\exporter;
+use renderer_base;
+
+/**
+ * Discussion summary exporter class.
+ *
+ * @copyright  2019 Andrew Nicols <andrew@nicols.co.uk>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class discussion_summary extends exporter {
+    /** @var discussion_summary_entity The discussion summary information */
+    private $summary;
+
+    /** @var stdClass[] The group information for each author */
+    private $groupsbyid;
+
+    /** @var stdClass[] The group information for each author */
+    private $groupsbyauthorid;
+
+    /** @var int The number of replies to the discussion */
+    private $replycount;
+
+    /** @var int number of unread posts if the user is tracking these */
+    private $unreadcount;
+
+    /** @var int The latest post id in the discussion */
+    private $latestpostid;
+
+    /** @var int|null The context id for the author of the first post */
+    private $firstpostauthorcontextid;
+
+    /** @var int|null The context id for the author of the latest post */
+    private $latestpostauthorcontextid;
+
+    /**
+     * Constructor.
+     *
+     * @param discussion_summary_entity $summary The discussion summary information
+     * @param stdClass[] $groupsbyid The group information for each author
+     * @param stdClass[] $groupsbyauthorid The group information for each author
+     * @param int $replycount The number of replies to the discussion
+     * @param int $unreadcount number of unread posts if the user is tracking these
+     * @param int $latestpostid The latest post id in the discussion
+     * @param int|null $firstpostauthorcontextid The context id for the author of the first post
+     * @param int|null $latestpostauthorcontextid The context id for the author of the latest post
+     * @param array $related The related objects
+     */
+    public function __construct(
+        discussion_summary_entity $summary,
+        array $groupsbyid,
+        array $groupsbyauthorid,
+        int $replycount,
+        int $unreadcount,
+        int $latestpostid,
+        ?int $firstpostauthorcontextid,
+        ?int $latestpostauthorcontextid,
+        array $related = []
+    ) {
+        $this->summary = $summary;
+        $this->groupsbyid = $groupsbyid;
+        $this->groupsbyauthorid = $groupsbyauthorid;
+        $this->replycount = $replycount;
+        $this->unreadcount = $unreadcount;
+        $this->latestpostid = $latestpostid;
+        $this->firstpostauthorcontextid = $firstpostauthorcontextid;
+        $this->latestpostauthorcontextid = $latestpostauthorcontextid;
+        return parent::__construct([], $related);
+    }
+
+    /**
+     * Return the list of additional properties.
+     *
+     * @return array
+     */
+    protected static function define_other_properties() {
+        return [
+            'id' => ['type' => PARAM_INT],
+            'discussion' => [
+                'type' => discussion::read_properties_definition(),
+            ],
+            'replies' => ['type' => PARAM_INT],
+            'unread' => ['type' => PARAM_INT],
+            'firstpostauthor' => [
+                'type' => author::read_properties_definition(),
+            ],
+            'latestpostauthor' => [
+                'type' => author::read_properties_definition(),
+            ],
+            'latestpostid' => ['type' => PARAM_INT],
+        ];
+    }
+
+    /**
+     * Get the additional values to inject while exporting.
+     *
+     * @param renderer_base $output The renderer.
+     * @return array Keys are the property names, values are their values.
+     */
+    protected function get_other_values(renderer_base $output) {
+        $capabilitymanager = $this->related['capabilitymanager'];
+        $forum = $this->related['forum'];
+        $user = $this->related['user'];
+        $latestpostauthor = $this->related['latestauthor'];
+        $discussion = $this->summary->get_discussion();
+
+        $related = (array) (object) $this->related;
+        $related['latestpostid'] = $this->latestpostid;
+        $related['groupsbyid'] = $this->groupsbyid;
+        $discussionexporter = new discussion($discussion, $related);
+
+        $related = [
+            'urlfactory' => $this->related['urlfactory'],
+            'context' => $this->related['forum']->get_context(),
+            'forum' => $forum,
+        ];
+
+        $firstpostauthor = new author(
+            $this->summary->get_first_post_author(),
+            $this->firstpostauthorcontextid,
+            $this->groupsbyauthorid[$this->summary->get_first_post_author()->get_id()],
+            $capabilitymanager->can_view_post(
+                $user,
+                $discussion,
+                $this->summary->get_first_post()
+            ),
+            $related
+        );
+
+        $latestpostauthor = new author(
+            $latestpostauthor ?? $this->summary->get_latest_post_author(),
+            $this->latestpostauthorcontextid,
+            [],
+            $capabilitymanager->can_view_post(
+                $user,
+                $discussion,
+                $this->summary->get_first_post()
+            ),
+            $related
+        );
+
+        return [
+            'id' => $discussion->get_id(),
+            'discussion' => $discussionexporter->export($output),
+            'replies' => $this->replycount,
+            'unread' => $this->unreadcount,
+            'firstpostauthor' => $firstpostauthor->export($output),
+            'latestpostauthor' => $latestpostauthor->export($output),
+            'latestpostid' => $this->latestpostid,
+        ];
+    }
+
+    /**
+     * Returns a list of objects that are related.
+     *
+     * @return array
+     */
+    protected static function define_related() {
+        return [
+            'legacydatamapperfactory' => 'mod_forum\local\factories\legacy_data_mapper',
+            'context' => 'context',
+            'forum' => 'mod_forum\local\entities\forum',
+            'capabilitymanager' => 'mod_forum\local\managers\capability',
+            'urlfactory' => 'mod_forum\local\factories\url',
+            'user' => 'stdClass',
+            'favouriteids' => 'int[]?',
+            'latestauthor' => 'mod_forum\local\entities\author?'
+        ];
+    }
+}

mod/forum/classes/local/exporters/forum.php

@@ -0,0 +1,194 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Forum Exporter.
+ *
+ * @package     mod_forum
+ * @copyright   2019 Andrew Nicols <andrew@nicols.co.uk>
+ * @license     http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_forum\local\exporters;
+
+defined('MOODLE_INTERNAL') || die();
+
+use mod_forum\local\entities\forum as forum_entity;
+use mod_forum\local\exporters\post as post_exporter;
+use core\external\exporter;
+use renderer_base;
+use stdClass;
+
+/**
+ * Forum class.
+ *
+ * @copyright   2019 Andrew Nicols <andrew@nicols.co.uk>
+ * @license     http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class forum extends exporter {
+    /** @var forum_entity The entity relating to the forum being displayed */
+    private $forum;
+
+    /**
+     * Constructor for the forum exporter.
+     *
+     * @param   forum_entity    $forum The forum being displayed
+     * @param   array           $related The related objects
+     */
+    public function __construct(forum_entity $forum, $related = []) {
+        $this->forum = $forum;
+        return parent::__construct([], $related);
+    }
+
+    /**
+     * Return the list of additional properties.
+     *
+     * @return array
+     */
+    protected static function define_other_properties() {
+        return [
+            'id' => ['type' => PARAM_INT],
+            'name' => ['type' => PARAM_RAW],
+            'state' => [
+                'type' => [
+                    'groupmode' => ['type' => PARAM_INT],
+                    'gradingenabled' => ['type' => PARAM_BOOL],
+                ],
+            ],
+            'userstate' => [
+                'type' => [
+                    'tracked' => ['type' => PARAM_INT],
+                ],
+            ],
+            'capabilities' => [
+                'type' => [
+                    'viewdiscussions' => ['type' => PARAM_BOOL],
+                    'create' => ['type' => PARAM_BOOL],
+                    'subscribe' => ['type' => PARAM_BOOL],
+                    'grade' => ['type' => PARAM_BOOL],
+                ]
+            ],
+            'urls' => [
+                'type' => [
+                    'create' => ['type' => PARAM_URL],
+                    'markasread' => ['type' => PARAM_URL],
+                    'view' => ['type' => PARAM_URL],
+                    'sortrepliesasc' => ['type' => PARAM_URL],
+                    'sortrepliesdesc' => ['type' => PARAM_URL],
+                    'sortlastpostasc' => ['type' => PARAM_URL],
+                    'sortlastpostdesc' => ['type' => PARAM_URL],
+                    'sortcreatedasc' => ['type' => PARAM_URL],
+                    'sortcreateddesc' => ['type' => PARAM_URL],
+                    'sortdiscussionasc' => ['type' => PARAM_URL],
+                    'sortdiscussiondesc' => ['type' => PARAM_URL],
+                    'sortstarterasc' => ['type' => PARAM_URL],
+                    'sortstarterdesc' => ['type' => PARAM_URL],
+                    'sortgroupasc' => ['type' => PARAM_URL],
+                    'sortgroupdesc' => ['type' => PARAM_URL],
+                ],
+            ],
+        ];
+    }
+
+    /**
+     * Get the additional values to inject while exporting.
+     *
+     * @param renderer_base $output The renderer.
+     * @return array Keys are the property names, values are their values.
+     */
+    protected function get_other_values(renderer_base $output) {
+        $capabilitymanager = $this->related['capabilitymanager'];
+        $urlfactory = $this->related['urlfactory'];
+        $user = $this->related['user'];
+        $currentgroup = $this->related['currentgroup'];
+        $vaultfactory = $this->related['vaultfactory'];
+        $discussionvault = $vaultfactory->get_discussions_in_forum_vault();
+
+        return [
+            'id' => $this->forum->get_id(),
+            'name' => $this->forum->get_name(),
+            'state' => [
+                'groupmode' => $this->forum->get_effective_group_mode(),
+                'gradingenabled' => $this->forum->is_grading_enabled()
+            ],
+            'userstate' => [
+                'tracked' => forum_tp_is_tracked($this->get_forum_record(), $this->related['user']),
+            ],
+            'capabilities' => [
+                'viewdiscussions' => $capabilitymanager->can_view_discussions($user),
+                'create' => $capabilitymanager->can_create_discussions($user, $currentgroup),
+                'selfenrol' => $capabilitymanager->can_self_enrol($user),
+                'subscribe' => $capabilitymanager->can_subscribe_to_forum($user),
+                'grade' => $capabilitymanager->can_grade($user),
+            ],
+            'urls' => [
+                'create' => $urlfactory->get_discussion_create_url($this->forum)->out(false),
+                'markasread' => $urlfactory->get_mark_all_discussions_as_read_url($this->forum)->out(false),
+                'view' => $urlfactory->get_forum_view_url_from_forum($this->forum)->out(false),
+                'sortrepliesasc' => $urlfactory->get_forum_view_url_from_forum($this->forum, null,
+                    $discussionvault::SORTORDER_REPLIES_ASC)->out(false),
+                'sortrepliesdesc' => $urlfactory->get_forum_view_url_from_forum($this->forum, null,
+                    $discussionvault::SORTORDER_REPLIES_DESC)->out(false),
+                'sortlastpostasc' => $urlfactory->get_forum_view_url_from_forum($this->forum, null,
+                    $discussionvault::SORTORDER_LASTPOST_ASC)->out(false),
+                'sortlastpostdesc' => $urlfactory->get_forum_view_url_from_forum($this->forum, null,
+                    $discussionvault::SORTORDER_LASTPOST_DESC)->out(false),
+                'sortcreatedasc' => $urlfactory->get_forum_view_url_from_forum($this->forum, null,
+                    $discussionvault::SORTORDER_CREATED_ASC)->out(false),
+                'sortcreateddesc' => $urlfactory->get_forum_view_url_from_forum($this->forum, null,
+                    $discussionvault::SORTORDER_CREATED_DESC)->out(false),
+                'sortdiscussionasc' => $urlfactory->get_forum_view_url_from_forum($this->forum, null,
+                    $discussionvault::SORTORDER_DISCUSSION_ASC)->out(false),
+                'sortdiscussiondesc' => $urlfactory->get_forum_view_url_from_forum($this->forum, null,
+                    $discussionvault::SORTORDER_DISCUSSION_DESC)->out(false),
+                'sortstarterasc' => $urlfactory->get_forum_view_url_from_forum($this->forum, null,
+                    $discussionvault::SORTORDER_STARTER_ASC)->out(false),
+                'sortstarterdesc' => $urlfactory->get_forum_view_url_from_forum($this->forum, null,
+                    $discussionvault::SORTORDER_STARTER_DESC)->out(false),
+                'sortgroupasc' => $urlfactory->get_forum_view_url_from_forum($this->forum, null,
+                    $discussionvault::SORTORDER_GROUP_ASC)->out(false),
+                'sortgroupdesc' => $urlfactory->get_forum_view_url_from_forum($this->forum, null,
+                    $discussionvault::SORTORDER_GROUP_DESC)->out(false),
+            ],
+        ];
+    }
+
+    /**
+     * Returns a list of objects that are related.
+     *
+     * @return array
+     */
+    protected static function define_related() {
+        return [
+            'legacydatamapperfactory' => 'mod_forum\local\factories\legacy_data_mapper',
+            'capabilitymanager' => 'mod_forum\local\managers\capability',
+            'urlfactory' => 'mod_forum\local\factories\url',
+            'user' => 'stdClass',
+            'currentgroup' => 'int?',
+            'vaultfactory' => 'mod_forum\local\factories\vault'
+        ];
+    }
+
+    /**
+     * Get the legacy forum record for this forum.
+     *
+     * @return  stdClass
+     */
+    private function get_forum_record(): stdClass {
+        $forumdbdatamapper = $this->related['legacydatamapperfactory']->get_forum_data_mapper();
+        return $forumdbdatamapper->to_legacy_object($this->forum);
+    }
+}

mod/forum/classes/local/exporters/group.php

@@ -0,0 +1,109 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Course Group exporter.
+ *
+ * @package    mod_forum
+ * @copyright  2019 Andrew Nicols <andrew@nicols.co.uk>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_forum\local\exporters;
+
+defined('MOODLE_INTERNAL') || die();
+
+use core\external\exporter;
+use renderer_base;
+use stdClass;
+
+require_once($CFG->dirroot . '/mod/forum/lib.php');
+
+/**
+ * Group exporter.
+ *
+ * @copyright  2019 Andrew Nicols <andrew@nicols.co.uk>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class group extends exporter {
+    /** @var stdClass $group Group */
+    private $group;
+
+    /**
+     * Constructor.
+     *
+     * @param stdClass $group The group to export
+     * @param array $related The related data for the export.
+     */
+    public function __construct(stdClass $group, array $related = []) {
+        $this->group = $group;
+        return parent::__construct([], $related);
+    }
+
+    /**
+     * Return the list of additional properties.
+     *
+     * @return array
+     */
+    protected static function define_other_properties() {
+        return [
+            'id' => [
+                'type' => PARAM_INT,
+                'optional' => true,
+                'default' => null,
+                'null' => NULL_ALLOWED
+            ],
+            'urls' => [
+                'type' => [
+                    'image' => [
+                        'description' => 'The URL for the group image',
+                        'type' => PARAM_URL,
+                        'optional' => true,
+                        'default' => null,
+                        'null' => NULL_ALLOWED
+                    ]
+                ],
+            ],
+        ];
+    }
+
+    /**
+     * Get the additional values to inject while exporting.
+     *
+     * @param renderer_base $output The renderer.
+     * @return array Keys are the property names, values are their values.
+     */
+    protected function get_other_values(renderer_base $output) {
+        return [
+            'id' => $group->id,
+            'urls' => [
+                'image' => $imageurl ? $imageurl->out(false) : null
+            ]
+        ];
+    }
+
+    /**
+     * Returns a list of objects that are related.
+     *
+     * @return array
+     */
+    protected static function define_related() {
+        return [
+            'urlmanager' => 'mod_forum\local\managers\url',
+            'context' => 'context'
+        ];
+    }
+}

mod/forum/classes/local/exporters/post.php

@@ -0,0 +1,703 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Post exporter class.
+ *
+ * @package    mod_forum
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_forum\local\exporters;
+
+defined('MOODLE_INTERNAL') || die();
+
+use mod_forum\local\entities\post as post_entity;
+use mod_forum\local\entities\discussion as discussion_entity;
+use mod_forum\local\exporters\author as author_exporter;
+use mod_forum\local\factories\exporter as exporter_factory;
+use core\external\exporter;
+use core_files\external\stored_file_exporter;
+use context;
+use core_tag_tag;
+use renderer_base;
+use stdClass;
+
+require_once($CFG->dirroot . '/mod/forum/lib.php');
+
+/**
+ * Post exporter class.
+ *
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class post extends exporter {
+    /** @var post_entity $post The post to export */
+    private $post;
+
+    /**
+     * Constructor.
+     *
+     * @param post_entity $post The post to export
+     * @param array $related List of related data
+     */
+    public function __construct(post_entity $post, array $related = []) {
+        $this->post = $post;
+        return parent::__construct([], $related);
+    }
+
+    /**
+     * Return the list of additional properties.
+     *
+     * @return array
+     */
+    protected static function define_other_properties() {
+        $attachmentdefinition = stored_file_exporter::read_properties_definition();
+        $attachmentdefinition['urls'] = [
+            'type' => [
+                'export' => [
+                    'type' => PARAM_URL,
+                    'description' => 'The URL used to export the attachment',
+                    'optional' => true,
+                    'default' => null,
+                    'null' => NULL_ALLOWED
+                ]
+            ]
+        ];
+        $attachmentdefinition['html'] = [
+            'type' => [
+                'plagiarism' => [
+                    'type' => PARAM_RAW,
+                    'description' => 'The HTML source for the Plagiarism Response',
+                    'optional' => true,
+                    'default' => null,
+                    'null' => NULL_ALLOWED
+                ],
+            ]
+        ];
+
+        return [
+            'id' => ['type' => PARAM_INT],
+            'subject' => ['type' => PARAM_TEXT],
+            'replysubject' => ['type' => PARAM_TEXT],
+            'message' => ['type' => PARAM_RAW],
+            'messageformat' => ['type' => PARAM_INT],
+            'author' => ['type' => author_exporter::read_properties_definition()],
+            'discussionid' => ['type' => PARAM_INT],
+            'hasparent' => ['type' => PARAM_BOOL],
+            'parentid' => [
+                'type' => PARAM_INT,
+                'optional' => true,
+                'default' => null,
+                'null' => NULL_ALLOWED
+            ],
+            'timecreated' => [
+                'type' => PARAM_INT,
+                'default' => null,
+                'null' => NULL_ALLOWED
+            ],
+            'timemodified' => [
+                'type' => PARAM_INT,
+                'default' => null,
+                'null' => NULL_ALLOWED
+            ],
+            'unread' => [
+                'type' => PARAM_BOOL,
+                'optional' => true,
+                'default' => null,
+                'null' => NULL_ALLOWED
+            ],
+            'isdeleted' => ['type' => PARAM_BOOL],
+            'isprivatereply' => ['type' => PARAM_BOOL],
+            'haswordcount' => ['type' => PARAM_BOOL],
+            'wordcount' => [
+                'type' => PARAM_INT,
+                'optional' => true,
+                'default' => null,
+                'null' => NULL_ALLOWED
+            ],
+            'charcount' => [
+                'type' => PARAM_INT,
+                'optional' => true,
+                'default' => null,
+                'null' => NULL_ALLOWED
+            ],
+            'capabilities' => [
+                'type' => [
+                    'view' => [
+                        'type' => PARAM_BOOL,
+                        'null' => NULL_ALLOWED,
+                        'description' => 'Whether the user can view the post',
+                    ],
+                    'edit' => [
+                        'type' => PARAM_BOOL,
+                        'null' => NULL_ALLOWED,
+                        'description' => 'Whether the user can edit the post',
+                    ],
+                    'delete' => [
+                        'type' => PARAM_BOOL,
+                        'null' => NULL_ALLOWED,
+                        'description' => 'Whether the user can delete the post',
+                    ],
+                    'split' => [
+                        'type' => PARAM_BOOL,
+                        'null' => NULL_ALLOWED,
+                        'description' => 'Whether the user can split the post',
+                    ],
+                    'reply' => [
+                        'type' => PARAM_BOOL,
+                        'null' => NULL_ALLOWED,
+                        'description' => 'Whether the user can reply to the post',
+                    ],
+                    'selfenrol' => [
+                        'type' => PARAM_BOOL,
+                        'null' => NULL_ALLOWED,
+                        'description' => 'Whether the user can self enrol into the course',
+                    ],
+                    'export' => [
+                        'type' => PARAM_BOOL,
+                        'null' => NULL_ALLOWED,
+                        'description' => 'Whether the user can export the post',
+                    ],
+                    'controlreadstatus' => [
+                        'type' => PARAM_BOOL,
+                        'null' => NULL_ALLOWED,
+                        'description' => 'Whether the user can control the read status of the post',
+                    ],
+                    'canreplyprivately' => [
+                        'type' => PARAM_BOOL,
+                        'null' => NULL_ALLOWED,
+                        'description' => 'Whether the user can post a private reply',
+                    ]
+                ]
+            ],
+            'urls' => [
+                'optional' => true,
+                'default' => null,
+                'null' => NULL_ALLOWED,
+                'type' => [
+                    'view' => [
+                        'description' => 'The URL used to view the post',
+                        'type' => PARAM_URL,
+                        'optional' => true,
+                        'default' => null,
+                        'null' => NULL_ALLOWED
+                    ],
+                    'viewisolated' => [
+                        'description' => 'The URL used to view the post in isolation',
+                        'type' => PARAM_URL,
+                        'optional' => true,
+                        'default' => null,
+                        'null' => NULL_ALLOWED
+                    ],
+                    'viewparent' => [
+                        'description' => 'The URL used to view the parent of the post',
+                        'type' => PARAM_URL,
+                        'optional' => true,
+                        'default' => null,
+                        'null' => NULL_ALLOWED
+                    ],
+                    'edit' => [
+                        'description' => 'The URL used to edit the post',
+                        'type' => PARAM_URL,
+                        'optional' => true,
+                        'default' => null,
+                        'null' => NULL_ALLOWED
+                    ],
+                    'delete' => [
+                        'description' => 'The URL used to delete the post',
+                        'type' => PARAM_URL,
+                        'optional' => true,
+                        'default' => null,
+                        'null' => NULL_ALLOWED
+                    ],
+                    'split' => [
+                        'description' => 'The URL used to split the discussion ' .
+                            'with the selected post being the first post in the new discussion',
+                        'type' => PARAM_URL,
+                        'optional' => true,
+                        'default' => null,
+                        'null' => NULL_ALLOWED
+                    ],
+                    'reply' => [
+                        'description' => 'The URL used to reply to the post',
+                        'type' => PARAM_URL,
+                        'optional' => true,
+                        'default' => null,
+                        'null' => NULL_ALLOWED
+                    ],
+                    'export' => [
+                        'description' => 'The URL used to export the post',
+                        'type' => PARAM_URL,
+                        'optional' => true,
+                        'default' => null,
+                        'null' => NULL_ALLOWED
+                    ],
+                    'markasread' => [
+                        'description' => 'The URL used to mark the post as read',
+                        'type' => PARAM_URL,
+                        'optional' => true,
+                        'default' => null,
+                        'null' => NULL_ALLOWED
+                    ],
+                    'markasunread' => [
+                        'description' => 'The URL used to mark the post as unread',
+                        'type' => PARAM_URL,
+                        'optional' => true,
+                        'default' => null,
+                        'null' => NULL_ALLOWED
+                    ],
+                    'discuss' => [
+                        'type' => PARAM_URL,
+                        'optional' => true,
+                        'default' => null,
+                        'null' => NULL_ALLOWED
+                    ]
+                ]
+            ],
+            'attachments' => [
+                'multiple' => true,
+                'type' => $attachmentdefinition
+            ],
+            'messageinlinefiles' => [
+                'optional' => true,
+                'multiple' => true,
+                'type' => stored_file_exporter::read_properties_definition(),
+            ],
+            'tags' => [
+                'optional' => true,
+                'default' => null,
+                'null' => NULL_ALLOWED,
+                'multiple' => true,
+                'type' => [
+                    'id' => [
+                        'type' => PARAM_INT,
+                        'description' => 'The ID of the Tag',
+                        'null' => NULL_NOT_ALLOWED,
+                    ],
+                    'tagid' => [
+                        'type' => PARAM_INT,
+                        'description' => 'The tagid',
+                        'null' => NULL_NOT_ALLOWED,
+                    ],
+                    'isstandard' => [
+                        'type' => PARAM_BOOL,
+                        'description' => 'Whether this is a standard tag',
+                        'null' => NULL_NOT_ALLOWED,
+                    ],
+                    'displayname' => [
+                        'type' => PARAM_TEXT,
+                        'description' => 'The display name of the tag',
+                        'null' => NULL_NOT_ALLOWED,
+                    ],
+                    'flag' => [
+                        'type' => PARAM_BOOL,
+                        'description' => 'Wehther this tag is flagged',
+                        'null' => NULL_NOT_ALLOWED,
+                    ],
+                    'urls' => [
+                        'description' => 'URLs associated with the tag',
+                        'null' => NULL_NOT_ALLOWED,
+                        'type' => [
+                            'view' => [
+                                'type' => PARAM_URL,
+                                'description' => 'The URL to view the tag',
+                                'null' => NULL_NOT_ALLOWED,
+                            ],
+                        ]
+                    ]
+                ]
+            ],
+            'html' => [
+                'optional' => true,
+                'default' => null,
+                'null' => NULL_ALLOWED,
+                'type' => [
+                    'rating' => [
+                        'optional' => true,
+                        'default' => null,
+                        'null' => NULL_ALLOWED,
+                        'type' => PARAM_RAW,
+                        'description' => 'The HTML source to rate the post',
+                    ],
+                    'taglist' => [
+                        'optional' => true,
+                        'default' => null,
+                        'null' => NULL_ALLOWED,
+                        'type' => PARAM_RAW,
+                        'description' => 'The HTML source to view the list of tags',
+                    ],
+                    'authorsubheading' => [
+                        'optional' => true,
+                        'default' => null,
+                        'null' => NULL_ALLOWED,
+                        'type' => PARAM_RAW,
+                        'description' => 'The HTML source to view the author details',
+                    ],
+                ]
+            ]
+        ];
+    }
+
+    /**
+     * Get the additional values to inject while exporting.
+     *
+     * @param renderer_base $output The renderer.
+     * @return array Keys are the property names, values are their values.
+     */
+    protected function get_other_values(renderer_base $output) {
+        $post = $this->post;
+        $authorgroups = $this->related['authorgroups'];
+        $forum = $this->related['forum'];
+        $discussion = $this->related['discussion'];
+        $author = $this->related['author'];
+        $authorcontextid = $this->related['authorcontextid'];
+        $user = $this->related['user'];
+        $readreceiptcollection = $this->related['readreceiptcollection'];
+        $rating = $this->related['rating'];
+        $tags = $this->related['tags'];
+        $attachments = $this->related['attachments'];
+        $inlineattachments = $this->related['messageinlinefiles'];
+        $includehtml = $this->related['includehtml'];
+        $isdeleted = $post->is_deleted();
+        $isprivatereply = $post->is_private_reply();
+        $hasrating = $rating != null;
+        $hastags = !empty($tags);
+        $discussionid = $post->get_discussion_id();
+        $parentid = $post->get_parent_id();
+
+        $capabilitymanager = $this->related['capabilitymanager'];
+        $canview = $capabilitymanager->can_view_post($user, $discussion, $post);
+        $canedit = $capabilitymanager->can_edit_post($user, $discussion, $post);
+        $candelete = $capabilitymanager->can_delete_post($user, $discussion, $post);
+        $cansplit = $capabilitymanager->can_split_post($user, $discussion, $post);
+        $canreply = $capabilitymanager->can_reply_to_post($user, $discussion, $post);
+        $canexport = $capabilitymanager->can_export_post($user, $post);
+        $cancontrolreadstatus = $capabilitymanager->can_manually_control_post_read_status($user);
+        $canselfenrol = $capabilitymanager->can_self_enrol($user);
+        $canreplyprivately = $capabilitymanager->can_reply_privately_to_post($user, $post);
+
+        $urlfactory = $this->related['urlfactory'];
+        $viewurl = $canview ? $urlfactory->get_view_post_url_from_post($post) : null;
+        $viewisolatedurl = $canview ? $urlfactory->get_view_isolated_post_url_from_post($post) : null;
+        $viewparenturl = $post->has_parent() ? $urlfactory->get_view_post_url_from_post_id($discussionid, $parentid) : null;
+        $editurl = $canedit ? $urlfactory->get_edit_post_url_from_post($forum, $post) : null;
+        $deleteurl = $candelete ? $urlfactory->get_delete_post_url_from_post($post) : null;
+        $spliturl = $cansplit ? $urlfactory->get_split_discussion_at_post_url_from_post($post) : null;
+        $replyurl = $canreply || $canselfenrol ? $urlfactory->get_reply_to_post_url_from_post($post) : null;
+        $exporturl = $canexport ? $urlfactory->get_export_post_url_from_post($post) : null;
+        $markasreadurl = $cancontrolreadstatus ? $urlfactory->get_mark_post_as_read_url_from_post($post) : null;
+        $markasunreadurl = $cancontrolreadstatus ? $urlfactory->get_mark_post_as_unread_url_from_post($post) : null;
+        $discussurl = $canview ? $urlfactory->get_discussion_view_url_from_post($post) : null;
+
+        $authorexporter = new author_exporter(
+            $author,
+            $authorcontextid,
+            $authorgroups,
+            $canview,
+            $this->related
+        );
+        $exportedauthor = $authorexporter->export($output);
+        // Only bother loading the content if the user can see it.
+        $loadcontent = $canview && !$isdeleted;
+        $exportattachments = $loadcontent && !empty($attachments);
+        $exportinlineattachments = $loadcontent && !empty($inlineattachments);
+
+        if ($loadcontent) {
+            $subject = $post->get_subject();
+            $timecreated = $this->get_start_time($discussion, $post);
+            $message = $this->get_message($post);
+        } else {
+            $subject = $isdeleted ? get_string('forumsubjectdeleted', 'forum') : get_string('forumsubjecthidden', 'forum');
+            $message = $isdeleted ? get_string('forumbodydeleted', 'forum') : get_string('forumbodyhidden', 'forum');
+            $timecreated = null;
+        }
+
+        $replysubject = $subject;
+        $strre = get_string('re', 'forum');
+        if (!(substr($replysubject, 0, strlen($strre)) == $strre)) {
+            $replysubject = "{$strre} {$replysubject}";
+        }
+
+        $showwordcount = $forum->should_display_word_count();
+        if ($showwordcount) {
+            $wordcount = $post->get_wordcount() ?? count_words($message);
+            $charcount = $post->get_charcount() ?? count_letters($message);
+        } else {
+            $wordcount = null;
+            $charcount = null;
+        }
+
+        return [
+            'id' => $post->get_id(),
+            'subject' => $subject,
+            'replysubject' => $replysubject,
+            'message' => $message,
+            'messageformat' => $post->get_message_format(),
+            'author' => $exportedauthor,
+            'discussionid' => $post->get_discussion_id(),
+            'hasparent' => $post->has_parent(),
+            'parentid' => $post->has_parent() ? $post->get_parent_id() : null,
+            'timecreated' => $timecreated,
+            'timemodified' => $post->get_time_modified(),
+            'unread' => ($loadcontent && $readreceiptcollection) ? !$readreceiptcollection->has_user_read_post($user, $post) : null,
+            'isdeleted' => $isdeleted,
+            'isprivatereply' => $isprivatereply,
+            'haswordcount' => $showwordcount,
+            'wordcount' => $wordcount,
+            'charcount' => $charcount,
+            'capabilities' => [
+                'view' => $canview,
+                'edit' => $canedit,
+                'delete' => $candelete,
+                'split' => $cansplit,
+                'reply' => $canreply,
+                'export' => $canexport,
+                'controlreadstatus' => $cancontrolreadstatus,
+                'canreplyprivately' => $canreplyprivately,
+                'selfenrol' => $canselfenrol
+            ],
+            'urls' => [
+                'view' => $viewurl ? $viewurl->out(false) : null,
+                'viewisolated' => $viewisolatedurl ? $viewisolatedurl->out(false) : null,
+                'viewparent' => $viewparenturl ? $viewparenturl->out(false) : null,
+                'edit' => $editurl ? $editurl->out(false) : null,
+                'delete' => $deleteurl ? $deleteurl->out(false) : null,
+                'split' => $spliturl ? $spliturl->out(false) : null,
+                'reply' => $replyurl ? $replyurl->out(false) : null,
+                'export' => $exporturl && $exporturl ? $exporturl->out(false) : null,
+                'markasread' => $markasreadurl ? $markasreadurl->out(false) : null,
+                'markasunread' => $markasunreadurl ? $markasunreadurl->out(false) : null,
+                'discuss' => $discussurl ? $discussurl->out(false) : null,
+            ],
+            'attachments' => ($exportattachments) ? $this->export_attachments($attachments, $post, $output, $canexport) : [],
+            'messageinlinefiles' => ($exportinlineattachments) ? $this->export_inline_attachments($inlineattachments,
+                $post, $output) : [],
+            'tags' => ($loadcontent && $hastags) ? $this->export_tags($tags) : [],
+            'html' => $includehtml ? [
+                'rating' => ($loadcontent && $hasrating) ? $output->render($rating) : null,
+                'taglist' => ($loadcontent && $hastags) ? $output->tag_list($tags) : null,
+                'authorsubheading' => ($loadcontent) ? $this->get_author_subheading_html($exportedauthor, $timecreated) : null
+            ] : null
+        ];
+    }
+
+    /**
+     * Returns a list of objects that are related.
+     *
+     * @return array
+     */
+    protected static function define_related() {
+        return [
+            'capabilitymanager' => 'mod_forum\local\managers\capability',
+            'readreceiptcollection' => 'mod_forum\local\entities\post_read_receipt_collection?',
+            'urlfactory' => 'mod_forum\local\factories\url',
+            'forum' => 'mod_forum\local\entities\forum',
+            'discussion' => 'mod_forum\local\entities\discussion',
+            'author' => 'mod_forum\local\entities\author',
+            'authorcontextid' => 'int?',
+            'user' => 'stdClass',
+            'context' => 'context',
+            'authorgroups' => 'stdClass[]',
+            'attachments' => '\stored_file[]?',
+            'messageinlinefiles' => '\stored_file[]?',
+            'tags' => '\core_tag_tag[]?',
+            'rating' => 'rating?',
+            'includehtml' => 'bool'
+        ];
+    }
+
+    /**
+     * This method returns the parameters for the post's message to
+     * use with the function \core_external\util::format_text().
+     *
+     * @return array
+     */
+    protected function get_format_parameters_for_message() {
+        return [
+            'component' => 'mod_forum',
+            'filearea' => 'post',
+            'itemid' => $this->post->get_id(),
+            'options' => [
+                'para' => false,
+                'trusted' => $this->post->is_message_trusted()
+            ]
+        ];
+    }
+
+    /**
+     * Get the message text from a post.
+     *
+     * @param post_entity $post The post
+     * @return string
+     */
+    private function get_message(post_entity $post): string {
+        global $CFG;
+
+        $message = $post->get_message();
+
+        if (!empty($CFG->enableplagiarism)) {
+            require_once($CFG->libdir . '/plagiarismlib.php');
+            $forum = $this->related['forum'];
+            $message .= plagiarism_get_links([
+                'userid' => $post->get_author_id(),
+                'content' => $message,
+                'cmid' => $forum->get_course_module_record()->id,
+                'course' => $forum->get_course_id(),
+                'forum' => $forum->get_id()
+            ]);
+        }
+
+        return $message;
+    }
+
+    /**
+     * Get the exported attachments for a post.
+     *
+     * @param stored_file[] $attachments The list of attachments for the post
+     * @param post_entity $post The post being exported
+     * @param renderer_base $output Renderer base
+     * @param bool $canexport If the user can export the post (relates to portfolios not exporters like this class)
+     * @return array
+     */
+    private function export_attachments(array $attachments, post_entity $post, renderer_base $output, bool $canexport): array {
+        global $CFG;
+
+        $urlfactory = $this->related['urlfactory'];
+        $enableplagiarism = $CFG->enableplagiarism;
+        $forum = $this->related['forum'];
+        $context = $this->related['context'];
+
+        if ($enableplagiarism) {
+            require_once($CFG->libdir . '/plagiarismlib.php' );
+        }
+
+        return array_map(function($attachment) use (
+            $output,
+            $enableplagiarism,
+            $canexport,
+            $context,
+            $forum,
+            $post,
+            $urlfactory
+        ) {
+            $exporter = new stored_file_exporter($attachment, ['context' => $context]);
+            $exportedattachment = $exporter->export($output);
+            $exporturl = $canexport ? $urlfactory->get_export_attachment_url_from_post_and_attachment($post, $attachment) : null;
+
+            if ($enableplagiarism) {
+                $plagiarismhtml = plagiarism_get_links([
+                    'userid' => $post->get_author_id(),
+                    'file' => $attachment,
+                    'cmid' => $forum->get_course_module_record()->id,
+                    'course' => $forum->get_course_id(),
+                    'forum' => $forum->get_id()
+                ]);
+            } else {
+                $plagiarismhtml = null;
+            }
+
+            $exportedattachment->urls = [
+                'export' => $exporturl ? $exporturl->out(false) : null
+            ];
+            $exportedattachment->html = [
+                'plagiarism' => $plagiarismhtml
+            ];
+
+            return $exportedattachment;
+        }, $attachments);
+    }
+
+    /**
+     * Get the exported inline attachments for a post.
+     *
+     * @param array $inlineattachments The list of inline attachments for the post
+     * @param post_entity $post The post being exported
+     * @param renderer_base $output Renderer base
+     * @return array
+     */
+    private function export_inline_attachments(array $inlineattachments, post_entity $post, renderer_base $output): array {
+
+        return array_map(function($attachment) use (
+            $output,
+            $post
+        ) {
+            $exporter = new stored_file_exporter($attachment, ['context' => $this->related['context']]);
+            return $exporter->export($output);;
+        }, $inlineattachments);
+    }
+
+    /**
+     * Export the list of tags.
+     *
+     * @param core_tag_tag[] $tags List of tags to export
+     * @return array
+     */
+    private function export_tags(array $tags): array {
+        $user = $this->related['user'];
+        $context = $this->related['context'];
+        $capabilitymanager = $this->related['capabilitymanager'];
+        $canmanagetags = $capabilitymanager->can_manage_tags($user);
+
+        return array_values(array_map(function($tag) use ($context, $canmanagetags) {
+            $viewurl = core_tag_tag::make_url($tag->tagcollid, $tag->rawname, 0, $context->id);
+            return [
+                'id' => $tag->taginstanceid,
+                'tagid' => $tag->id,
+                'isstandard' => $tag->isstandard,
+                'displayname' => $tag->get_display_name(),
+                'flag' => $canmanagetags && !empty($tag->flag),
+                'urls' => [
+                    'view' => $viewurl->out(false)
+                ]
+            ];
+        }, $tags));
+    }
+
+    /**
+     * Get the HTML to display as a subheading in a post.
+     *
+     * @param stdClass $exportedauthor The exported author object
+     * @param int $timecreated The post time created timestamp if it's to be displayed
+     * @return string
+     */
+    private function get_author_subheading_html(stdClass $exportedauthor, int $timecreated): string {
+        $fullname = $exportedauthor->fullname;
+        $profileurl = $exportedauthor->urls['profile'] ?? null;
+        $name = $profileurl ? "<a href=\"{$profileurl}\">{$fullname}</a>" : $fullname;
+        $date = userdate_htmltime($timecreated, get_string('strftimedaydatetime', 'core_langconfig'));
+        return get_string('bynameondate', 'mod_forum', ['name' => $name, 'date' => $date]);
+    }
+
+    /**
+     * Get the start time for a post.
+     *
+     * @param discussion_entity $discussion entity
+     * @param post_entity $post entity
+     * @return int The start time (timestamp) for a post
+     */
+    private function get_start_time(discussion_entity $discussion, post_entity $post) {
+        global $CFG;
+
+        $posttime = $post->get_time_created();
+        $discussiontime = $discussion->get_time_start();
+        if (!empty($CFG->forum_enabletimedposts) && ($discussiontime > $posttime)) {
+            return $discussiontime;
+        }
+        return $posttime;
+    }
+}

mod/forum/classes/local/exporters/posts.php

@@ -0,0 +1,182 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Posts exporter class.
+ *
+ * @package    mod_forum
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_forum\local\exporters;
+
+defined('MOODLE_INTERNAL') || die();
+
+use mod_forum\local\entities\author as author_entity;
+use mod_forum\local\entities\post as post_entity;
+use mod_forum\local\exporters\post as post_exporter;
+use core\external\exporter;
+use renderer_base;
+
+require_once($CFG->dirroot . '/mod/forum/lib.php');
+
+/**
+ * Posts exporter class.
+ *
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class posts extends exporter {
+    /** @var post_entity[] $posts List of posts to export */
+    private $posts;
+    /** @var author_entity[] $authorsbyid List of authors for the posts indexed by author id */
+    private $authorsbyid;
+    /** @var int[] $authorcontextids List of authors context ids indexed by author id */
+    private $authorcontextids;
+    /** @var array $attachmentsbypostid List of attachments indexed by post id */
+    private $attachmentsbypostid;
+    /** @var array $inlineattachmentsbypostid List of inline attachments indexed by post id */
+    private $inlineattachmentsbypostid;
+    /** @var array $groupsbyauthorid List of author's groups indexed by author id */
+    private $groupsbyauthorid;
+    /** @var array $tagsbypostid List of tags indexed by post id */
+    private $tagsbypostid;
+    /** @var array $ratingbypostid List of ratings indexed by post id */
+    private $ratingbypostid;
+
+    /**
+     * Constructor.
+     *
+     * @param post_entity[] $posts List of posts to export
+     * @param author_entity[] $authorsbyid List of authors for the posts indexed by author id
+     * @param int[] $authorcontextids List of authors context ids indexed by author id
+     * @param array $attachmentsbypostid List of attachments indexed by post id
+     * @param array $groupsbyauthorid List of author's groups indexed by author id
+     * @param array $tagsbypostid List of tags indexed by post id
+     * @param array $ratingbypostid List of ratings indexed by post id
+     * @param array $related The related objects for exporting
+     * @param array $inlineattachmentsbypostid List of inline attachments indexed by post id
+     */
+    public function __construct(
+        array $posts,
+        array $authorsbyid = [],
+        array $authorcontextids = [],
+        array $attachmentsbypostid = [],
+        array $groupsbyauthorid = [],
+        array $tagsbypostid = [],
+        array $ratingbypostid = [],
+        array $related = [],
+        array $inlineattachmentsbypostid = []
+    ) {
+        $this->posts = $posts;
+        $this->authorsbyid = $authorsbyid;
+        $this->authorcontextids = $authorcontextids;
+        $this->attachmentsbypostid = $attachmentsbypostid;
+        $this->inlineattachmentsbypostid = $inlineattachmentsbypostid;
+        $this->groupsbyauthorid = $groupsbyauthorid;
+        $this->tagsbypostid = $tagsbypostid;
+        $this->ratingbypostid = $ratingbypostid;
+        return parent::__construct([], $related);
+    }
+
+    /**
+     * Return the list of additional properties.
+     *
+     * @return array
+     */
+    protected static function define_other_properties() {
+        return [
+            'posts' => [
+                'type' => post_exporter::read_properties_definition(),
+                'multiple' => true
+            ]
+        ];
+    }
+
+    /**
+     * Get the additional values to inject while exporting.
+     *
+     * @param renderer_base $output The renderer.
+     * @return array Keys are the property names, values are their values.
+     */
+    protected function get_other_values(renderer_base $output) {
+        $related = $this->related;
+        $authorsbyid = $this->authorsbyid;
+        $authorcontextids = $this->authorcontextids;
+        $attachmentsbypostid = $this->attachmentsbypostid;
+        $inlineattachmentsbypostid = $this->inlineattachmentsbypostid;
+        $groupsbyauthorid = $this->groupsbyauthorid;
+        $tagsbypostid = $this->tagsbypostid;
+        $ratingbypostid = $this->ratingbypostid;
+        $exportedposts = array_map(
+            function($post) use (
+                $related,
+                $authorsbyid,
+                $authorcontextids,
+                $attachmentsbypostid,
+                $groupsbyauthorid,
+                $tagsbypostid,
+                $ratingbypostid,
+                $output,
+                $inlineattachmentsbypostid
+            ) {
+                $authorid = $post->get_author_id();
+                $postid = $post->get_id();
+                $author = isset($authorsbyid[$authorid]) ? $authorsbyid[$authorid] : [];
+                $authorcontextid = isset($authorcontextids[$authorid]) ? $authorcontextids[$authorid] : null;
+                $attachments = isset($attachmentsbypostid[$postid]) ? $attachmentsbypostid[$postid] : [];
+                $inlineattachments = isset($inlineattachmentsbypostid[$postid]) ? $inlineattachmentsbypostid[$postid] : [];
+                $authorgroups = isset($groupsbyauthorid[$authorid]) ? $groupsbyauthorid[$authorid] : [];
+                $tags = isset($tagsbypostid[$postid]) ? $tagsbypostid[$postid] : [];
+                $rating = isset($ratingbypostid[$postid]) ? $ratingbypostid[$postid] : null;
+                $exporter = new post_exporter($post, array_merge($related, [
+                    'author' => $author,
+                    'authorcontextid' => $authorcontextid,
+                    'attachments' => $attachments,
+                    'messageinlinefiles' => $inlineattachments,
+                    'authorgroups' => $authorgroups,
+                    'tags' => $tags,
+                    'rating' => $rating
+                ]));
+                return $exporter->export($output);
+            },
+            $this->posts
+        );
+
+        return [
+            'posts' => $exportedposts
+        ];
+    }
+
+    /**
+     * Returns a list of objects that are related.
+     *
+     * @return array
+     */
+    protected static function define_related() {
+        return [
+            'capabilitymanager' => 'mod_forum\local\managers\capability',
+            'urlfactory' => 'mod_forum\local\factories\url',
+            'forum' => 'mod_forum\local\entities\forum',
+            'discussion' => 'mod_forum\local\entities\discussion',
+            'readreceiptcollection' => 'mod_forum\local\entities\post_read_receipt_collection?',
+            'user' => 'stdClass',
+            'context' => 'context',
+            'includehtml' => 'bool'
+        ];
+    }
+}

mod/forum/classes/local/factories/builder.php

@@ -0,0 +1,127 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Builder factory.
+ *
+ * @package    mod_forum
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_forum\local\factories;
+
+defined('MOODLE_INTERNAL') || die();
+
+use mod_forum\local\builders\exported_posts as exported_posts_builder;
+use mod_forum\local\builders\exported_discussion_summaries as exported_discussion_summaries_builder;
+use mod_forum\local\builders\exported_discussion as exported_discussion_builder;
+use mod_forum\local\factories\vault as vault_factory;
+use mod_forum\local\factories\legacy_data_mapper as legacy_data_mapper_factory;
+use mod_forum\local\factories\exporter as exporter_factory;
+use mod_forum\local\factories\manager as manager_factory;
+use renderer_base;
+
+/**
+ * Builder factory to construct any builders for forum.
+ *
+ * See:
+ * https://designpatternsphp.readthedocs.io/en/latest/Creational/SimpleFactory/README.html
+ *
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class builder {
+    /** @var legacy_data_mapper_factory $legacydatamapperfactory Legacy data mapper factory */
+    private $legacydatamapperfactory;
+    /** @var exporter_factory $exporterfactory Exporter factory */
+    private $exporterfactory;
+    /** @var vault_factory $vaultfactory Vault factory */
+    private $vaultfactory;
+    /** @var manager_factory $managerfactory Manager factory */
+    private $managerfactory;
+    /** @var renderer_base $rendererbase Renderer base */
+    private $rendererbase;
+
+    /**
+     * Constructor.
+     *
+     * @param legacy_data_mapper_factory $legacydatamapperfactory Legacy data mapper factory
+     * @param exporter_factory $exporterfactory Exporter factory
+     * @param vault_factory $vaultfactory Vault factory
+     * @param manager_factory $managerfactory Manager factory
+     * @param renderer_base $rendererbase Renderer base
+     */
+    public function __construct(
+        legacy_data_mapper_factory $legacydatamapperfactory,
+        exporter_factory $exporterfactory,
+        vault_factory $vaultfactory,
+        manager_factory $managerfactory,
+        renderer_base $rendererbase
+    ) {
+        $this->legacydatamapperfactory = $legacydatamapperfactory;
+        $this->exporterfactory = $exporterfactory;
+        $this->vaultfactory = $vaultfactory;
+        $this->managerfactory = $managerfactory;
+        $this->rendererbase = $rendererbase;
+    }
+
+
+    /**
+     * Get an instance of the exported posts builder.
+     *
+     * @return exported_posts_builder
+     */
+    public function get_exported_posts_builder(): exported_posts_builder {
+        return new exported_posts_builder(
+            $this->rendererbase,
+            $this->legacydatamapperfactory,
+            $this->exporterfactory,
+            $this->vaultfactory,
+            $this->managerfactory
+        );
+    }
+
+    /**
+     * Get an instance of the exported discussion summaries builder.
+     *
+     * @return exported_discussion_summaries_builder
+     */
+    public function get_exported_discussion_summaries_builder(): exported_discussion_summaries_builder {
+        return new exported_discussion_summaries_builder(
+            $this->rendererbase,
+            $this->legacydatamapperfactory,
+            $this->exporterfactory,
+            $this->vaultfactory,
+            $this->managerfactory
+        );
+    }
+
+    /**
+     * Get an instance of the exported discussion builder.
+     *
+     * @return exported_discussion_summaries_builder
+     */
+    public function get_exported_discussion_builder(): exported_discussion_builder {
+        return new exported_discussion_builder(
+            $this->rendererbase,
+            $this->legacydatamapperfactory,
+            $this->exporterfactory,
+            $this->vaultfactory,
+            $this->managerfactory->get_rating_manager()
+        );
+    }
+}

mod/forum/classes/local/factories/entity.php

@@ -0,0 +1,258 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Entity factory.
+ *
+ * @package    mod_forum
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_forum\local\factories;
+
+defined('MOODLE_INTERNAL') || die();
+
+use mod_forum\local\entities\author as author_entity;
+use mod_forum\local\entities\discussion as discussion_entity;
+use mod_forum\local\entities\discussion_summary as discussion_summary_entity;
+use mod_forum\local\entities\forum as forum_entity;
+use mod_forum\local\entities\post as post_entity;
+use mod_forum\local\entities\post_read_receipt_collection as post_read_receipt_collection_entity;
+use mod_forum\local\entities\sorter as sorter_entity;
+use stdClass;
+use context;
+use cm_info;
+use user_picture;
+use moodle_url;
+
+/**
+ * Entity factory to create the forum entities.
+ *
+ * See:
+ * https://designpatternsphp.readthedocs.io/en/latest/Creational/SimpleFactory/README.html
+ *
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class entity {
+    /**
+     * Create a forum entity from a stdClass (legacy forum object).
+     *
+     * @param stdClass $record The forum record
+     * @param context $context The forum module context
+     * @param stdClass $coursemodule Course module record for the forum
+     * @param stdClass $course Course the forum belongs to
+     * @return forum_entity
+     */
+    public function get_forum_from_stdclass(
+        stdClass $record,
+        context $context,
+        stdClass $coursemodule,
+        stdClass $course
+    ): forum_entity {
+        // Note: cm_info::create loads a cm_info in the context of the current user which
+        // creates hidden dependency on the logged in user (very bad) however it's the best
+        // option to load some data we need which doesn't require the logged in user.
+        // Only use properties which do not require the logged in user.
+        $cm = \cm_info::create($coursemodule);
+
+        return new forum_entity(
+            $context,
+            $coursemodule,
+            $course,
+            // This property is a general module property that isn't affected by the logged in user.
+            $cm->effectivegroupmode,
+            $record->id,
+            $record->course,
+            $record->type,
+            $record->name,
+            $record->intro,
+            $record->introformat,
+            $record->assessed,
+            $record->assesstimestart,
+            $record->assesstimefinish,
+            $record->scale,
+            $record->grade_forum,
+            $record->grade_forum_notify,
+            $record->maxbytes,
+            $record->maxattachments,
+            $record->forcesubscribe,
+            $record->trackingtype,
+            $record->rsstype,
+            $record->rssarticles,
+            $record->timemodified,
+            $record->warnafter,
+            $record->blockafter,
+            $record->blockperiod,
+            $record->completiondiscussions,
+            $record->completionreplies,
+            $record->completionposts,
+            $record->displaywordcount,
+            $record->lockdiscussionafter,
+            $record->duedate,
+            $record->cutoffdate
+        );
+    }
+
+    /**
+     * Create a discussion entity from an stdClass (legacy dicussion object).
+     *
+     * @param stdClass $record Discussion record
+     * @return discussion_entity
+     */
+    public function get_discussion_from_stdclass(stdClass $record): discussion_entity {
+        return new discussion_entity(
+            $record->id,
+            $record->course,
+            $record->forum,
+            $record->name,
+            $record->firstpost,
+            $record->userid,
+            $record->groupid,
+            $record->assessed,
+            $record->timemodified,
+            $record->usermodified,
+            $record->timestart,
+            $record->timeend,
+            $record->pinned,
+            $record->timelocked
+        );
+    }
+
+    /**
+     * Create a post entity from an stdClass (legacy post object).
+     *
+     * @param stdClass $record The post record
+     * @return post_entity
+     */
+    public function get_post_from_stdclass(stdClass $record): post_entity {
+        return new post_entity(
+            $record->id,
+            $record->discussion,
+            $record->parent,
+            $record->userid,
+            $record->created,
+            $record->modified,
+            $record->mailed,
+            $record->subject,
+            $record->message,
+            $record->messageformat,
+            $record->messagetrust,
+            $record->attachment,
+            $record->totalscore,
+            $record->mailnow,
+            $record->deleted,
+            $record->privatereplyto,
+            $record->wordcount,
+            $record->charcount
+        );
+    }
+
+    /**
+     * Create an author entity from a user record.
+     *
+     * @param stdClass $record The user record
+     * @return author_entity
+     */
+    public function get_author_from_stdclass(stdClass $record): author_entity {
+        return new author_entity(
+            $record->id,
+            $record->picture,
+            $record->firstname,
+            $record->lastname,
+            fullname($record),
+            $record->email,
+            $record->deleted,
+            $record->middlename,
+            $record->firstnamephonetic,
+            $record->lastnamephonetic,
+            $record->alternatename,
+            $record->imagealt
+        );
+    }
+
+    /**
+     * Create a discussion summary enttiy from stdClasses.
+     *
+     * @param stdClass $discussion The discussion record
+     * @param stdClass $firstpost A post record for the first post in the discussion
+     * @param stdClass $firstpostauthor A user record for the author of the first post
+     * @param stdClass $latestpostauthor A user record for the author of the latest post in the discussion
+     * @return discussion_summary_entity
+     */
+    public function get_discussion_summary_from_stdclass(
+        stdClass $discussion,
+        stdClass $firstpost,
+        stdClass $firstpostauthor,
+        stdClass $latestpostauthor
+    ): discussion_summary_entity {
+
+        $firstpostauthorentity = $this->get_author_from_stdclass($firstpostauthor);
+        return new discussion_summary_entity(
+            $this->get_discussion_from_stdclass($discussion),
+            $this->get_post_from_stdclass($firstpost, $firstpostauthorentity),
+            $firstpostauthorentity,
+            $this->get_author_from_stdclass($latestpostauthor)
+        );
+    }
+
+    /**
+     * Create a post read receipt collection entity from a list of read receipt records.
+     *
+     * @param array $records A list of read receipt records.
+     * @return post_read_receipt_collection_entity
+     */
+    public function get_post_read_receipt_collection_from_stdclasses(array $records): post_read_receipt_collection_entity {
+        return new post_read_receipt_collection_entity($records);
+    }
+
+    /**
+     * Create a sorter entity to sort post entities.
+     *
+     * @return sorter_entity
+     */
+    public function get_posts_sorter(): sorter_entity {
+        return new sorter_entity(
+            // Get id function for a post_entity.
+            function(post_entity $post) {
+                return $post->get_id();
+            },
+            // Get parent id function for a post_entity.
+            function(post_entity $post) {
+                return $post->get_parent_id();
+            }
+        );
+    }
+
+    /**
+     * Create a sorter entity to sort exported posts.
+     *
+     * @return sorter_entity
+     */
+    public function get_exported_posts_sorter(): sorter_entity {
+        return new sorter_entity(
+            // Get id function for an exported post.
+            function(stdClass $post) {
+                return $post->id;
+            },
+            // Get parent id function for an exported post.
+            function(stdClass $post) {
+                return $post->parentid;
+            }
+        );
+    }
+}

mod/forum/classes/local/factories/exporter.php

@@ -0,0 +1,275 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Forum Exporter factory.
+ *
+ * @package    mod_forum
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_forum\local\factories;
+
+defined('MOODLE_INTERNAL') || die();
+
+use mod_forum\local\entities\discussion as discussion_entity;
+use mod_forum\local\entities\forum as forum_entity;
+use mod_forum\local\entities\post as post_entity;
+use mod_forum\local\entities\post_read_receipt_collection as post_read_receipt_collection_entity;
+use mod_forum\local\factories\legacy_data_mapper as legacy_data_mapper_factory;
+use mod_forum\local\factories\manager as manager_factory;
+use mod_forum\local\factories\url as url_factory;
+use mod_forum\local\factories\vault as vault_factory;
+use mod_forum\local\exporters\forum as forum_exporter;
+use mod_forum\local\exporters\discussion as discussion_exporter;
+use mod_forum\local\exporters\discussion_summaries as discussion_summaries_exporter;
+use mod_forum\local\exporters\post as post_exporter;
+use mod_forum\local\exporters\posts as posts_exporter;
+use context;
+use rating;
+use stdClass;
+
+/**
+ * The exporter factory class used to fetch an instance of the different exporter types.
+ *
+ * See:
+ * https://designpatternsphp.readthedocs.io/en/latest/Creational/SimpleFactory/README.html
+ *
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class exporter {
+    /** @var legacy_data_mapper_factory The factory to fetch a legacy data mapper */
+    private $legacydatamapperfactory;
+
+    /** @var manager_factory The factory to fetch a new manager */
+    private $managerfactory;
+
+    /** @var url_factory The factory to create urls */
+    private $urlfactory;
+
+    /** @var vault_factory The vault factory */
+    private $vaultfactory;
+
+    /**
+     * Constructor for the exporter factory.
+     *
+     * @param legacy_data_mapper_factory $legacydatamapperfactory The factory to fetch a legacy data mapper instance
+     * @param manager_factory $managerfactory The factory fo fetch a manager instance
+     * @param url_factory $urlfactory The factory to create urls
+     * @param vault_factory $vaultfactory The vault factory
+     */
+    public function __construct(legacy_data_mapper_factory $legacydatamapperfactory, manager_factory $managerfactory,
+            url_factory $urlfactory, vault_factory $vaultfactory) {
+        $this->legacydatamapperfactory = $legacydatamapperfactory;
+        $this->managerfactory = $managerfactory;
+        $this->urlfactory = $urlfactory;
+        $this->vaultfactory = $vaultfactory;
+    }
+
+    /**
+     * Construct a new forum exporter for the specified user and forum.
+     *
+     * @param   stdClass        $user The user viewing the forum
+     * @param   forum_entity    $forum The forum being viewed
+     * @param   int             $currentgroup The group currently being viewed
+     * @return  forum_exporter
+     */
+    public function get_forum_exporter(
+        stdClass $user,
+        forum_entity $forum,
+        ?int $currentgroup
+    ): forum_exporter {
+        return new forum_exporter($forum, [
+            'legacydatamapperfactory' => $this->legacydatamapperfactory,
+            'capabilitymanager' => $this->managerfactory->get_capability_manager($forum),
+            'urlfactory' => $this->urlfactory,
+            'user' => $user,
+            'currentgroup' => $currentgroup,
+            'vaultfactory' => $this->vaultfactory,
+        ]);
+    }
+
+    /**
+     * Fetch the structure of the forum exporter.
+     *
+     * @return  array
+     */
+    public static function get_forum_export_structure(): array {
+        return forum_exporter::read_properties_definition();
+    }
+
+    /**
+     * Construct a new discussion exporter for the specified user and forum discussion.
+     *
+     * @param   stdClass          $user The user viewing the forum
+     * @param   forum_entity      $forum The forum being viewed
+     * @param   discussion_entity $discussion The discussion being viewed
+     * @param   stdClass[]        $groupsbyid The list of groups in the forum
+     * @return  discussion_exporter
+     */
+    public function get_discussion_exporter(
+        stdClass $user,
+        forum_entity $forum,
+        discussion_entity $discussion,
+        array $groupsbyid = [],
+        array $favouriteids = []
+    ): discussion_exporter {
+        return new discussion_exporter($discussion, [
+            'context' => $forum->get_context(),
+            'forum' => $forum,
+            'capabilitymanager' => $this->managerfactory->get_capability_manager($forum),
+            'urlfactory' => $this->urlfactory,
+            'user' => $user,
+            'legacydatamapperfactory' => $this->legacydatamapperfactory,
+            'latestpostid' => null,
+            'groupsbyid' => $groupsbyid,
+            'favouriteids' => $favouriteids
+        ]);
+    }
+
+    /**
+     * Fetch the structure of the discussion exporter.
+     *
+     * @return  array
+     */
+    public static function get_discussion_export_structure() {
+        return discussion_exporter::read_properties_definition();
+    }
+
+    /**
+     * Construct a new discussion summaries exporter for the specified user and set of discussions.
+     *
+     * @param   stdClass        $user The user viewing the forum
+     * @param   forum_entity    $forum The forum being viewed
+     * @param   discussion_summary_entity[] $discussions The set of discussion summaries to export
+     * @param   stdClass[]      $groupsbyauthorid The set of groups in an associative array for each author
+     * @param   stdClass[]      $groupsbyid The set of groups in the forum in an associative array for each group
+     * @param   int[]           $discussionreplycount The number of replies for each discussion
+     * @param   int[]           $discussionunreadcount The number of unread posts for each discussion
+     * @param   int[]           $latestpostids The latest post id for each discussion
+     * @param   int[]           $postauthorcontextids The context ids for the first and last post authors (indexed by author id)
+     * @param   int[]           $favourites The list of discussion ids that have been favourited
+     * @return  discussion_summaries_exporter
+     */
+    public function get_discussion_summaries_exporter(
+        stdClass $user,
+        forum_entity $forum,
+        array $discussions,
+        array $groupsbyid = [],
+        array $groupsbyauthorid = [],
+        array $discussionreplycount = [],
+        array $discussionunreadcount = [],
+        array $latestpostids = [],
+        array $postauthorcontextids = [],
+        array $favourites = [],
+        array $latestauthors = []
+    ): discussion_summaries_exporter {
+        return new discussion_summaries_exporter(
+            $discussions,
+            $groupsbyid,
+            $groupsbyauthorid,
+            $discussionreplycount,
+            $discussionunreadcount,
+            $latestpostids,
+            $postauthorcontextids,
+            [
+                'legacydatamapperfactory' => $this->legacydatamapperfactory,
+                'context' => $forum->get_context(),
+                'forum' => $forum,
+                'capabilitymanager' => $this->managerfactory->get_capability_manager($forum),
+                'urlfactory' => $this->urlfactory,
+                'user' => $user,
+                'favouriteids' => $favourites,
+                'latestauthors' => $latestauthors
+            ]
+        );
+    }
+
+    /**
+     * Fetch the structure of the discussion summaries exporter.
+     *
+     * @return  array
+     */
+    public static function get_discussion_summaries_export_structure() {
+        return discussion_summaries_exporter::read_properties_definition();
+    }
+
+    /**
+     * Construct a new post exporter for the specified user and set of post.
+     *
+     * @param   stdClass        $user The user viewing the forum
+     * @param   forum_entity    $forum The forum being viewed
+     * @param   discussion_entity $discussion The discussion that the post is in
+     * @param   post_entity[]   $posts The set of posts to be exported
+     * @param   author_entity[] $authorsbyid List of authors indexed by author id
+     * @param   int[]           $authorcontextids List of authors context ids indexed by author id
+     * @param   array           $attachmentsbypostid List of attachments for each post indexed by post id
+     * @param   array           $groupsbyauthorid List of groups for the post authors indexed by author id
+     * @param   post_read_receipt_collection_entity|null $readreceiptcollection Details of read receipts for each post
+     * @param   array           $tagsbypostid List of tags for each post indexed by post id
+     * @param   rating[]        $ratingbypostid List of ratings for each post indexed by post id
+     * @param   bool            $includehtml Include some pre-constructed HTML in the export
+     * @param   array           $inlineattachmentsbypostid List of attachments for each post indexed by post id
+     * @return  posts_exporter
+     */
+    public function get_posts_exporter(
+        stdClass $user,
+        forum_entity $forum,
+        discussion_entity $discussion,
+        array $posts,
+        array $authorsbyid = [],
+        array $authorcontextids = [],
+        array $attachmentsbypostid = [],
+        array $groupsbyauthorid = [],
+        post_read_receipt_collection_entity $readreceiptcollection = null,
+        array $tagsbypostid = [],
+        array $ratingbypostid = [],
+        bool $includehtml = false,
+        array $inlineattachmentsbypostid = []
+    ): posts_exporter {
+        return new posts_exporter(
+            $posts,
+            $authorsbyid,
+            $authorcontextids,
+            $attachmentsbypostid,
+            $groupsbyauthorid,
+            $tagsbypostid,
+            $ratingbypostid,
+            [
+                'capabilitymanager' => $this->managerfactory->get_capability_manager($forum),
+                'urlfactory' => $this->urlfactory,
+                'forum' => $forum,
+                'discussion' => $discussion,
+                'user' => $user,
+                'context' => $forum->get_context(),
+                'readreceiptcollection' => $readreceiptcollection,
+                'includehtml' => $includehtml
+            ],
+            $inlineattachmentsbypostid
+        );
+    }
+
+    /**
+     * Fetch the structure of the posts exporter.
+     *
+     * @return  array
+     */
+    public static function get_posts_export_structure() {
+        return posts_exporter::read_properties_definition();
+    }
+}

mod/forum/classes/local/factories/legacy_data_mapper.php

@@ -0,0 +1,99 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Legacy data mapper factory.
+ *
+ * @package    mod_forum
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_forum\local\factories;
+
+defined('MOODLE_INTERNAL') || die();
+
+use mod_forum\local\data_mappers\legacy\author as author_data_mapper;
+use mod_forum\local\data_mappers\legacy\discussion as discussion_data_mapper;
+use mod_forum\local\data_mappers\legacy\forum as forum_data_mapper;
+use mod_forum\local\data_mappers\legacy\post as post_data_mapper;
+use mod_forum\local\entities\forum;
+
+/**
+ * Legacy data mapper factory.
+ *
+ * See:
+ * https://designpatternsphp.readthedocs.io/en/latest/Creational/SimpleFactory/README.html
+ *
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class legacy_data_mapper {
+    /**
+     * Create a legacy forum data mapper.
+     *
+     * @return forum_data_mapper
+     */
+    public function get_forum_data_mapper(): forum_data_mapper {
+        return new forum_data_mapper();
+    }
+
+    /**
+     * Create a legacy discussion data mapper.
+     *
+     * @return discussion_data_mapper
+     */
+    public function get_discussion_data_mapper(): discussion_data_mapper {
+        return new discussion_data_mapper();
+    }
+
+    /**
+     * Create a legacy post data mapper.
+     *
+     * @return post_data_mapper
+     */
+    public function get_post_data_mapper(): post_data_mapper {
+        return new post_data_mapper();
+    }
+
+    /**
+     * Create a legacy author data mapper.
+     *
+     * @return author_data_mapper
+     */
+    public function get_author_data_mapper(): author_data_mapper {
+        return new author_data_mapper();
+    }
+
+    /**
+     * Get the corresponding entity based on the supplied value
+     *
+     * @param string $entity
+     * @return author_data_mapper|discussion_data_mapper|forum_data_mapper|post_data_mapper
+     */
+    public function get_legacy_data_mapper_for_vault($entity) {
+        switch($entity) {
+            case 'forum':
+                return $this->get_forum_data_mapper();
+            case 'discussion':
+                return $this->get_discussion_data_mapper();
+            case 'post':
+                return $this->get_post_data_mapper();
+            case 'author':
+                return $this->get_author_data_mapper();
+        }
+    }
+}

mod/forum/classes/local/factories/manager.php

@@ -0,0 +1,81 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Managers factory.
+ *
+ * @package    mod_forum
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_forum\local\factories;
+
+defined('MOODLE_INTERNAL') || die();
+
+global $CFG;
+require_once($CFG->dirroot . '/rating/lib.php');
+
+use mod_forum\local\entities\forum as forum_entity;
+use mod_forum\local\managers\capability as capability_manager;
+use rating_manager;
+
+/**
+ * Managers factory.
+ *
+ * See:
+ * https://designpatternsphp.readthedocs.io/en/latest/Creational/SimpleFactory/README.html
+ *
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class manager {
+    /** @var legacy_data_mapper $legacydatamapperfactory Legacy data mapper factory */
+    private $legacydatamapperfactory;
+
+    /**
+     * Constructor.
+     *
+     * @param legacy_data_mapper $legacydatamapperfactory Legacy data mapper factory
+     */
+    public function __construct(legacy_data_mapper $legacydatamapperfactory) {
+        $this->legacydatamapperfactory = $legacydatamapperfactory;
+    }
+
+    /**
+     * Create a capability manager for the given forum.
+     *
+     * @param forum_entity $forum The forum to manage capabilities for
+     * @return capability_manager
+     */
+    public function get_capability_manager(forum_entity $forum) {
+        return new capability_manager(
+            $forum,
+            $this->legacydatamapperfactory->get_forum_data_mapper(),
+            $this->legacydatamapperfactory->get_discussion_data_mapper(),
+            $this->legacydatamapperfactory->get_post_data_mapper()
+        );
+    }
+
+    /**
+     * Create a rating manager.
+     *
+     * @return rating_manager
+     */
+    public function get_rating_manager(): rating_manager {
+        return new rating_manager();
+    }
+}

mod/forum/classes/local/factories/renderer.php

@@ -0,0 +1,638 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Renderer factory.
+ *
+ * @package    mod_forum
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_forum\local\factories;
+
+defined('MOODLE_INTERNAL') || die();
+
+use mod_forum\grades\forum_gradeitem;
+use mod_forum\local\entities\discussion as discussion_entity;
+use mod_forum\local\entities\forum as forum_entity;
+use mod_forum\local\factories\vault as vault_factory;
+use mod_forum\local\factories\legacy_data_mapper as legacy_data_mapper_factory;
+use mod_forum\local\factories\entity as entity_factory;
+use mod_forum\local\factories\exporter as exporter_factory;
+use mod_forum\local\factories\manager as manager_factory;
+use mod_forum\local\factories\builder as builder_factory;
+use mod_forum\local\factories\url as url_factory;
+use mod_forum\local\renderers\discussion as discussion_renderer;
+use mod_forum\local\renderers\discussion_list as discussion_list_renderer;
+use mod_forum\local\renderers\posts as posts_renderer;
+use moodle_page;
+use core\output\notification;
+
+/**
+ * Renderer factory.
+ *
+ * See:
+ * https://designpatternsphp.readthedocs.io/en/latest/Creational/SimpleFactory/README.html
+ *
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class renderer {
+    /** @var legacy_data_mapper_factory $legacydatamapperfactory Legacy data mapper factory */
+    private $legacydatamapperfactory;
+    /** @var exporter_factory $exporterfactory Exporter factory */
+    private $exporterfactory;
+    /** @var vault_factory $vaultfactory Vault factory */
+    private $vaultfactory;
+    /** @var manager_factory $managerfactory Manager factory */
+    private $managerfactory;
+    /** @var entity_factory $entityfactory Entity factory */
+    private $entityfactory;
+    /** @var builder_factory $builderfactory Builder factory */
+    private $builderfactory;
+    /** @var url_factory $urlfactory URL factory */
+    private $urlfactory;
+    /** @var renderer_base $rendererbase Renderer base */
+    private $rendererbase;
+    /** @var moodle_page $page Moodle page */
+    private $page;
+
+    /**
+     * Constructor.
+     *
+     * @param legacy_data_mapper_factory $legacydatamapperfactory Legacy data mapper factory
+     * @param exporter_factory $exporterfactory Exporter factory
+     * @param vault_factory $vaultfactory Vault factory
+     * @param manager_factory $managerfactory Manager factory
+     * @param entity_factory $entityfactory Entity factory
+     * @param builder_factory $builderfactory Builder factory
+     * @param url_factory $urlfactory URL factory
+     * @param moodle_page $page Moodle page
+     */
+    public function __construct(
+        legacy_data_mapper_factory $legacydatamapperfactory,
+        exporter_factory $exporterfactory,
+        vault_factory $vaultfactory,
+        manager_factory $managerfactory,
+        entity_factory $entityfactory,
+        builder_factory $builderfactory,
+        url_factory $urlfactory,
+        moodle_page $page
+    ) {
+        $this->legacydatamapperfactory = $legacydatamapperfactory;
+        $this->exporterfactory = $exporterfactory;
+        $this->vaultfactory = $vaultfactory;
+        $this->managerfactory = $managerfactory;
+        $this->entityfactory = $entityfactory;
+        $this->builderfactory = $builderfactory;
+        $this->urlfactory = $urlfactory;
+        $this->page = $page;
+        $this->rendererbase = $page->get_renderer('mod_forum');
+    }
+
+    /**
+     * Create a discussion renderer for the given forum and discussion.
+     *
+     * @param forum_entity $forum Forum the discussion belongs to
+     * @param discussion_entity $discussion Discussion to render
+     * @param int $displaymode How should the posts be formatted?
+     * @return discussion_renderer
+     */
+    public function get_discussion_renderer(
+        forum_entity $forum,
+        discussion_entity $discussion,
+        int $displaymode
+    ): discussion_renderer {
+
+        $capabilitymanager = $this->managerfactory->get_capability_manager($forum);
+        $ratingmanager = $this->managerfactory->get_rating_manager();
+        $rendererbase = $this->rendererbase;
+
+        $baseurl = $this->urlfactory->get_discussion_view_url_from_discussion($discussion);
+        $notifications = [];
+
+        return new discussion_renderer(
+            $forum,
+            $discussion,
+            $displaymode,
+            $rendererbase,
+            $this->get_single_discussion_posts_renderer($displaymode, false),
+            $this->page,
+            $this->legacydatamapperfactory,
+            $this->exporterfactory,
+            $this->vaultfactory,
+            $this->urlfactory,
+            $this->entityfactory,
+            $capabilitymanager,
+            $ratingmanager,
+            $this->entityfactory->get_exported_posts_sorter(),
+            $baseurl,
+            $notifications,
+            function($discussion, $user, $forum) {
+                $exportbuilder = $this->builderfactory->get_exported_discussion_builder();
+                return $exportbuilder->build(
+                    $user,
+                    $forum,
+                    $discussion
+                );
+            }
+        );
+    }
+
+    /**
+     * Create a posts renderer to render posts without defined parent/reply relationships.
+     *
+     * @return posts_renderer
+     */
+    public function get_posts_renderer(): posts_renderer {
+        return new posts_renderer(
+            $this->rendererbase,
+            $this->builderfactory->get_exported_posts_builder(),
+            'mod_forum/forum_discussion_posts'
+        );
+    }
+
+    /**
+     * Create a posts renderer to render a list of posts in a single discussion.
+     *
+     * @param int|null $displaymode How should the posts be formatted?
+     * @param bool $readonly Should the posts include the actions to reply, delete, etc?
+     * @return posts_renderer
+     */
+    public function get_single_discussion_posts_renderer(int $displaymode = null, bool $readonly = false): posts_renderer {
+        $exportedpostssorter = $this->entityfactory->get_exported_posts_sorter();
+
+        switch ($displaymode) {
+            case FORUM_MODE_THREADED:
+                $template = 'mod_forum/forum_discussion_threaded_posts';
+                break;
+            case FORUM_MODE_NESTED:
+                $template = 'mod_forum/forum_discussion_nested_posts';
+                break;
+            case FORUM_MODE_NESTED_V2:
+                $template = 'mod_forum/forum_discussion_nested_v2_posts';
+                break;
+            default;
+                $template = 'mod_forum/forum_discussion_posts';
+                break;
+        }
+
+        return new posts_renderer(
+            $this->rendererbase,
+            $this->builderfactory->get_exported_posts_builder(),
+            $template,
+            // Post process the exported posts for our template. This function will add the "replies"
+            // and "hasreplies" properties to the exported posts. It will also sort them into the
+            // reply tree structure if the display mode requires it.
+            function($exportedposts, $forums, $discussions) use ($displaymode, $readonly, $exportedpostssorter) {
+                $forum = array_shift($forums);
+                $seenfirstunread = false;
+                $postcount = count($exportedposts);
+                $discussionsbyid = array_reduce($discussions, function($carry, $discussion) {
+                    $carry[$discussion->get_id()] = $discussion;
+                    return $carry;
+                }, []);
+                $exportedposts = array_map(
+                    function($exportedpost) use ($forum, $discussionsbyid, $readonly, $seenfirstunread, $displaymode) {
+                        $discussion = $discussionsbyid[$exportedpost->discussionid] ?? null;
+                        if ($forum->get_type() == 'single' && !$exportedpost->hasparent) {
+                            // Remove the author from any posts that don't have a parent.
+                            unset($exportedpost->author);
+                            unset($exportedpost->html['authorsubheading']);
+                        }
+
+                        $exportedpost->firstpost = false;
+                        $exportedpost->readonly = $readonly;
+                        $exportedpost->hasreplycount = false;
+                        $exportedpost->hasreplies = false;
+                        $exportedpost->replies = [];
+                        $exportedpost->discussionlocked = $discussion ? $discussion->is_locked() : null;
+
+                        $exportedpost->isfirstunread = false;
+                        if (!$seenfirstunread && $exportedpost->unread) {
+                            $exportedpost->isfirstunread = true;
+                            $seenfirstunread = true;
+                        }
+
+                        if ($displaymode === FORUM_MODE_NESTED_V2) {
+                            $exportedpost->showactionmenu = $exportedpost->capabilities['view'] ||
+                                                            $exportedpost->capabilities['controlreadstatus'] ||
+                                                            $exportedpost->capabilities['edit'] ||
+                                                            $exportedpost->capabilities['split'] ||
+                                                            $exportedpost->capabilities['delete'] ||
+                                                            $exportedpost->capabilities['export'] ||
+                                                            !empty($exportedpost->urls['viewparent']);
+                        }
+
+                        return $exportedpost;
+                    },
+                    $exportedposts
+                );
+
+                if (
+                    $displaymode === FORUM_MODE_NESTED ||
+                    $displaymode === FORUM_MODE_THREADED ||
+                    $displaymode === FORUM_MODE_NESTED_V2
+                ) {
+                    $sortedposts = $exportedpostssorter->sort_into_children($exportedposts);
+                    $sortintoreplies = function($nestedposts) use (&$sortintoreplies) {
+                        return array_map(function($postdata) use (&$sortintoreplies) {
+                            [$post, $replies] = $postdata;
+                            $totalreplycount = 0;
+
+                            if (empty($replies)) {
+                                $post->replies = [];
+                                $post->hasreplies = false;
+                            } else {
+                                $sortedreplies = $sortintoreplies($replies);
+                                // Set the parent author name on the replies. This is used for screen
+                                // readers to help them identify the structure of the discussion.
+                                $sortedreplies = array_map(function($reply) use ($post) {
+                                    if (isset($post->author)) {
+                                        $reply->parentauthorname = $post->author->fullname;
+                                    } else {
+                                        // The only time the author won't be set is for a single discussion
+                                        // forum. See above for where it gets unset.
+                                        $reply->parentauthorname = get_string('firstpost', 'mod_forum');
+                                    }
+                                    return $reply;
+                                }, $sortedreplies);
+
+                                $totalreplycount = array_reduce($sortedreplies, function($carry, $reply) {
+                                    return $carry + 1 + $reply->totalreplycount;
+                                }, $totalreplycount);
+
+                                $post->replies = $sortedreplies;
+                                $post->hasreplies = true;
+                            }
+
+                            $post->totalreplycount = $totalreplycount;
+
+                            return $post;
+                        }, $nestedposts);
+                    };
+                    // Set the "replies" property on the exported posts.
+                    $exportedposts = $sortintoreplies($sortedposts);
+                } else if ($displaymode === FORUM_MODE_FLATNEWEST || $displaymode === FORUM_MODE_FLATOLDEST) {
+                    $exportedfirstpost = array_shift($exportedposts);
+                    $exportedfirstpost->replies = $exportedposts;
+                    $exportedfirstpost->hasreplies = true;
+                    $exportedposts = [$exportedfirstpost];
+                }
+
+                if (!empty($exportedposts)) {
+                    // Need to identify the first post so that we can use it in behat tests.
+                    $exportedposts[0]->firstpost = true;
+                    $exportedposts[0]->hasreplycount = true;
+                    $exportedposts[0]->replycount = $postcount - 1;
+                }
+
+                return $exportedposts;
+            }
+        );
+    }
+
+    /**
+     * Create a posts renderer to render posts in the forum search results.
+     *
+     * @param string[] $searchterms The search terms to be highlighted in the posts
+     * @return posts_renderer
+     */
+    public function get_posts_search_results_renderer(array $searchterms): posts_renderer {
+        $urlfactory = $this->urlfactory;
+
+        return new posts_renderer(
+            $this->rendererbase,
+            $this->builderfactory->get_exported_posts_builder(),
+            'mod_forum/forum_search_results',
+            // Post process the exported posts to add the highlighting of the search terms to the post
+            // and also the additional context links in the subject.
+            function($exportedposts, $forumsbyid, $discussionsbyid) use ($searchterms, $urlfactory) {
+                $highlightwords = implode(' ', $searchterms);
+
+                return array_map(
+                    function($exportedpost) use (
+                        $forumsbyid,
+                        $discussionsbyid,
+                        $searchterms,
+                        $highlightwords,
+                        $urlfactory
+                    ) {
+                        $discussion = $discussionsbyid[$exportedpost->discussionid];
+                        $forum = $forumsbyid[$discussion->get_forum_id()];
+
+                        $viewdiscussionurl = $urlfactory->get_discussion_view_url_from_discussion($discussion);
+                        $exportedpost->urls['viewforum'] = $urlfactory->get_forum_view_url_from_forum($forum)->out(false);
+                        $exportedpost->urls['viewdiscussion'] = $viewdiscussionurl->out(false);
+                        $exportedpost->subject = highlight($highlightwords, $exportedpost->subject);
+                        $exportedpost->forumname = format_string($forum->get_name(), true);
+                        $exportedpost->discussionname = highlight($highlightwords, format_string($discussion->get_name(), true));
+                        $exportedpost->showdiscussionname = $forum->get_type() != 'single';
+
+                        // Identify search terms only found in HTML markup, and add a warning about them to
+                        // the start of the message text. This logic was copied exactly as is from the previous
+                        // implementation.
+                        $missingterms = '';
+                        $exportedpost->message = highlight(
+                            $highlightwords,
+                            $exportedpost->message,
+                            0,
+                            '<fgw9sdpq4>',
+                            '</fgw9sdpq4>'
+                        );
+
+                        foreach ($searchterms as $searchterm) {
+                            if (
+                                preg_match("/$searchterm/i", $exportedpost->message) &&
+                                !preg_match('/<fgw9sdpq4>' . $searchterm . '<\/fgw9sdpq4>/i', $exportedpost->message)
+                            ) {
+                                $missingterms .= " $searchterm";
+                            }
+                        }
+
+                        $exportedpost->message = str_replace('<fgw9sdpq4>', '<span class="highlight">', $exportedpost->message);
+                        $exportedpost->message = str_replace('</fgw9sdpq4>', '</span>', $exportedpost->message);
+
+                        if ($missingterms) {
+                            $strmissingsearchterms = get_string('missingsearchterms', 'forum');
+                            $exportedpost->message = '<p class="highlight2">' . $strmissingsearchterms . ' '
+                                . $missingterms . '</p>' . $exportedpost->message;
+                        }
+
+                        return $exportedpost;
+                    },
+                    $exportedposts
+                );
+            }
+        );
+    }
+
+    /**
+     * Create a posts renderer to render posts in mod/forum/user.php.
+     *
+     * @param bool $addlinkstocontext Should links to the course, forum, and discussion be included?
+     * @return posts_renderer
+     */
+    public function get_user_forum_posts_report_renderer(bool $addlinkstocontext): posts_renderer {
+        $urlfactory = $this->urlfactory;
+
+        return new posts_renderer(
+            $this->rendererbase,
+            $this->builderfactory->get_exported_posts_builder(),
+            'mod_forum/forum_posts_with_context_links',
+            function($exportedposts, $forumsbyid, $discussionsbyid) use ($urlfactory, $addlinkstocontext) {
+
+                return array_map(function($exportedpost) use ($forumsbyid, $discussionsbyid, $addlinkstocontext, $urlfactory) {
+                    $discussion = $discussionsbyid[$exportedpost->discussionid];
+                    $forum = $forumsbyid[$discussion->get_forum_id()];
+                    $courserecord = $forum->get_course_record();
+
+                    if ($addlinkstocontext) {
+                        $viewdiscussionurl = $urlfactory->get_discussion_view_url_from_discussion($discussion);
+                        $exportedpost->urls['viewforum'] = $urlfactory->get_forum_view_url_from_forum($forum)->out(false);
+                        $exportedpost->urls['viewdiscussion'] = $viewdiscussionurl->out(false);
+                        $exportedpost->urls['viewcourse'] = $urlfactory->get_course_url_from_forum($forum)->out(false);
+                    }
+
+                    $exportedpost->forumname = format_string($forum->get_name(), true);
+                    $exportedpost->discussionname = format_string($discussion->get_name(), true);
+                    $exportedpost->coursename = format_string($courserecord->shortname, true);
+                    $exportedpost->showdiscussionname = $forum->get_type() != 'single';
+
+                    return $exportedpost;
+                }, $exportedposts);
+            }
+        );
+    }
+
+    /**
+     * Create a standard type discussion list renderer.
+     *
+     * @param forum_entity $forum The forum that the discussions belong to
+     * @return discussion_list_renderer
+     */
+    public function get_discussion_list_renderer(
+        forum_entity $forum
+    ): discussion_list_renderer {
+
+        $capabilitymanager = $this->managerfactory->get_capability_manager($forum);
+        $rendererbase = $this->rendererbase;
+        $notifications = [];
+
+        switch ($forum->get_type()) {
+            case 'news':
+                if (SITEID == $forum->get_course_id()) {
+                    $template = 'mod_forum/frontpage_news_discussion_list';
+                } else {
+                    $template = 'mod_forum/news_discussion_list';
+                }
+                break;
+            case 'qanda':
+                $template = 'mod_forum/qanda_discussion_list';
+                break;
+            default:
+                $template = 'mod_forum/discussion_list';
+        }
+
+        return new discussion_list_renderer(
+            $forum,
+            $rendererbase,
+            $this->legacydatamapperfactory,
+            $this->exporterfactory,
+            $this->vaultfactory,
+            $this->builderfactory,
+            $capabilitymanager,
+            $this->urlfactory,
+            forum_gradeitem::load_from_forum_entity($forum),
+            $template,
+            $notifications,
+            function($discussions, $user, $forum) {
+
+                $exporteddiscussionsummarybuilder = $this->builderfactory->get_exported_discussion_summaries_builder();
+                return $exporteddiscussionsummarybuilder->build(
+                    $user,
+                    $forum,
+                    $discussions
+                );
+            }
+        );
+    }
+
+    /**
+     * Create a discussion list renderer which shows more information about the first post.
+     *
+     * @param forum_entity $forum The forum that the discussions belong to
+     * @param string $template The template to use
+     * @return discussion_list_renderer
+     */
+    private function get_detailed_discussion_list_renderer(
+        forum_entity $forum,
+        string $template
+    ): discussion_list_renderer {
+
+        $capabilitymanager = $this->managerfactory->get_capability_manager($forum);
+        $rendererbase = $this->rendererbase;
+        $notifications = [];
+
+        return new discussion_list_renderer(
+            $forum,
+            $rendererbase,
+            $this->legacydatamapperfactory,
+            $this->exporterfactory,
+            $this->vaultfactory,
+            $this->builderfactory,
+            $capabilitymanager,
+            $this->urlfactory,
+            forum_gradeitem::load_from_forum_entity($forum),
+            $template,
+            $notifications,
+            function($discussions, $user, $forum) use ($capabilitymanager) {
+                $exportedpostsbuilder = $this->builderfactory->get_exported_posts_builder();
+                $discussionentries = [];
+                $postentries = [];
+                foreach ($discussions as $discussion) {
+                    $discussionentries[] = $discussion->get_discussion();
+                    $discussionentriesids[] = $discussion->get_discussion()->get_id();
+                    $postentries[] = $discussion->get_first_post();
+                }
+
+                $exportedposts['posts'] = $exportedpostsbuilder->build(
+                    $user,
+                    [$forum],
+                    $discussionentries,
+                    $postentries
+                );
+
+                $postvault = $this->vaultfactory->get_post_vault();
+                $canseeanyprivatereply = $capabilitymanager->can_view_any_private_reply($user);
+                $discussionrepliescount = $postvault->get_reply_count_for_discussion_ids(
+                        $user,
+                        $discussionentriesids,
+                        $canseeanyprivatereply
+                    );
+                $forumdatamapper = $this->legacydatamapperfactory->get_forum_data_mapper();
+                $forumrecord = $forumdatamapper->to_legacy_object($forum);
+                if (forum_tp_is_tracked($forumrecord, $user)) {
+                    $discussionunreadscount = $postvault->get_unread_count_for_discussion_ids(
+                            $user,
+                            $discussionentriesids,
+                            $canseeanyprivatereply
+                    );
+                } else {
+                    $discussionunreadscount = [];
+                }
+
+                array_walk($exportedposts['posts'], function($post) use ($discussionrepliescount, $discussionunreadscount) {
+                    $post->discussionrepliescount = $discussionrepliescount[$post->discussionid] ?? 0;
+                    $post->discussionunreadscount = $discussionunreadscount[$post->discussionid] ?? 0;
+                    // TODO: Find a better solution due to language differences when defining the singular and plural form.
+                    $post->isreplyplural = $post->discussionrepliescount != 1 ? true : false;
+                    $post->isunreadplural = $post->discussionunreadscount != 1 ? true : false;
+                });
+
+                $exportedposts['state']['hasdiscussions'] = $exportedposts['posts'] ? true : false;
+
+                return $exportedposts;
+            }
+        );
+    }
+
+    /**
+     * Create a blog type discussion list renderer.
+     *
+     * @param forum_entity $forum The forum that the discussions belong to
+     * @return discussion_list_renderer
+     */
+    public function get_blog_discussion_list_renderer(
+        forum_entity $forum
+    ): discussion_list_renderer {
+        return $this->get_detailed_discussion_list_renderer($forum, 'mod_forum/blog_discussion_list');
+    }
+
+    /**
+     * Create a discussion list renderer for the social course format.
+     *
+     * @param forum_entity $forum The forum that the discussions belong to
+     * @return discussion_list_renderer
+     */
+    public function get_social_discussion_list_renderer(
+        forum_entity $forum
+    ): discussion_list_renderer {
+        return $this->get_detailed_discussion_list_renderer($forum, 'mod_forum/social_discussion_list');
+    }
+
+    /**
+     * Create a discussion list renderer for the social course format.
+     *
+     * @param forum_entity $forum The forum that the discussions belong to
+     * @return discussion_list_renderer
+     */
+    public function get_frontpage_news_discussion_list_renderer(
+        forum_entity $forum
+    ): discussion_list_renderer {
+        return $this->get_detailed_discussion_list_renderer($forum, 'mod_forum/frontpage_social_discussion_list');
+    }
+
+    /**
+     * Create a single type discussion list renderer.
+     *
+     * @param forum_entity $forum Forum the discussion belongs to
+     * @param discussion_entity $discussion The discussion entity
+     * @param bool $hasmultiplediscussions Whether the forum has multiple discussions (more than one)
+     * @param int $displaymode How should the posts be formatted?
+     * @return discussion_renderer
+     */
+    public function get_single_discussion_list_renderer(
+        forum_entity $forum,
+        discussion_entity $discussion,
+        bool $hasmultiplediscussions,
+        int $displaymode
+    ): discussion_renderer {
+
+        $capabilitymanager = $this->managerfactory->get_capability_manager($forum);
+        $ratingmanager = $this->managerfactory->get_rating_manager();
+        $rendererbase = $this->rendererbase;
+
+        $cmid = $forum->get_course_module_record()->id;
+        $baseurl = $this->urlfactory->get_forum_view_url_from_course_module_id($cmid);
+        $notifications = array();
+
+        if ($hasmultiplediscussions) {
+            $notifications[] = (new notification(get_string('warnformorepost', 'forum')))
+                ->set_show_closebutton(true);
+        }
+
+        return new discussion_renderer(
+            $forum,
+            $discussion,
+            $displaymode,
+            $rendererbase,
+            $this->get_single_discussion_posts_renderer($displaymode, false),
+            $this->page,
+            $this->legacydatamapperfactory,
+            $this->exporterfactory,
+            $this->vaultfactory,
+            $this->urlfactory,
+            $this->entityfactory,
+            $capabilitymanager,
+            $ratingmanager,
+            $this->entityfactory->get_exported_posts_sorter(),
+            $baseurl,
+            $notifications
+        );
+    }
+}

mod/forum/classes/local/factories/url.php

@@ -0,0 +1,507 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * A URL factory for the forum.
+ *
+ * @package    mod_forum
+ * @copyright  2019 Andrew Nicols <andrew@nicols.co.uk>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_forum\local\factories;
+
+defined('MOODLE_INTERNAL') || die();
+
+use mod_forum\local\entities\author as author_entity;
+use mod_forum\local\entities\forum as forum_entity;
+use mod_forum\local\entities\discussion as discussion_entity;
+use mod_forum\local\entities\post as post_entity;
+use mod_forum\local\factories\legacy_data_mapper as legacy_data_mapper_factory;
+use moodle_url;
+use stored_file;
+use user_picture;
+
+require_once($CFG->dirroot . '/mod/forum/lib.php');
+
+/**
+ * A URL factory for the forum.
+ *
+ * @copyright  2019 Andrew Nicols <andrew@nicols.co.uk>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class url {
+    /** @var legacy_data_mapper_factory $legacydatamapperfactory Legacy data mapper factory */
+    private $legacydatamapperfactory;
+
+    /**
+     * Constructor.
+     *
+     * @param legacy_data_mapper_factory $legacydatamapperfactory Legacy data mapper factory
+     */
+    public function __construct(legacy_data_mapper_factory $legacydatamapperfactory) {
+        $this->legacydatamapperfactory = $legacydatamapperfactory;
+    }
+
+    /**
+     * Get the course url from the given course id.
+     *
+     * @param int $courseid The course id
+     * @return moodle_url
+     */
+    public function get_course_url_from_courseid(int $courseid): moodle_url {
+        return new moodle_url('/course/view.php', [
+            'id' => $courseid,
+        ]);
+    }
+
+    /**
+     * Get the course url from the given forum entity.
+     *
+     * @param forum_entity $forum The forum entity
+     * @return moodle_url
+     */
+    public function get_course_url_from_forum(forum_entity $forum): moodle_url {
+        return $this->get_course_url_from_courseid($forum->get_course_id());
+    }
+
+    /**
+     * Get the create discussion url for the given forum.
+     *
+     * @param forum_entity $forum The forum entity
+     * @return moodle_url
+     */
+    public function get_discussion_create_url(forum_entity $forum): moodle_url {
+        return new moodle_url('/mod/forum/post.php', [
+            'forum' => $forum->get_id(),
+        ]);
+    }
+
+    /**
+     * Get the view forum url for the given forum and optionally a page number.
+     *
+     * @param forum_entity $forum The forum entity
+     * @param int|null $pageno The page number
+     * @param int|null $sortorder The sorting order
+     * @return moodle_url
+     */
+    public function get_forum_view_url_from_forum(forum_entity $forum, ?int $pageno = null,
+            ?int $sortorder = null): moodle_url {
+
+        return $this->get_forum_view_url_from_course_module_id($forum->get_course_module_record()->id, $pageno, $sortorder);
+    }
+
+    /**
+     * Get the view forum url for the given course module id and optionally a page number.
+     *
+     * @param int $coursemoduleid The course module id
+     * @param int|null $pageno The page number
+     * @param int|null $sortorder The sorting order
+     * @return moodle_url
+     */
+    public function get_forum_view_url_from_course_module_id(int $coursemoduleid, ?int $pageno = null,
+            ?int $sortorder = null): moodle_url {
+
+        $url = new moodle_url('/mod/forum/view.php', [
+            'id' => $coursemoduleid,
+        ]);
+
+        if (null !== $pageno) {
+            $url->param('p', $pageno);
+        }
+
+        if (null !== $sortorder) {
+            $url->param('o', $sortorder);
+        }
+
+        return $url;
+    }
+
+    /**
+     * Get the view discussion url from the given discussion id.
+     *
+     * @param int $discussionid The discussion id
+     * @return moodle_url
+     */
+    public function get_discussion_view_url_from_discussion_id(int $discussionid): moodle_url {
+        return new moodle_url('/mod/forum/discuss.php', [
+            'd' => $discussionid
+        ]);
+    }
+
+    /**
+     * Get the view discussion url from the given discussion.
+     *
+     * @param discussion_entity $discussion The discussion
+     * @return moodle_url
+     */
+    public function get_discussion_view_url_from_discussion(discussion_entity $discussion): moodle_url {
+        return $this->get_discussion_view_url_from_discussion_id($discussion->get_id());
+    }
+
+    /**
+     * Get the url to view the first unread post in a discussion.
+     *
+     * @param discussion_entity $discussion The discussion
+     * @return moodle_url
+     */
+    public function get_discussion_view_first_unread_post_url_from_discussion(discussion_entity $discussion) {
+        $viewurl = $this->get_discussion_view_url_from_discussion_id($discussion->get_id());
+        $viewurl->set_anchor('unread');
+
+        return $viewurl;
+    }
+
+    /**
+     * Get the url to view the latest post in a discussion.
+     *
+     * @param discussion_entity $discussion The discussion
+     * @param int|null $latestpost The id of the latest post
+     * @return moodle_url
+     */
+    public function get_discussion_view_latest_post_url_from_discussion(discussion_entity $discussion, ?int $latestpost) {
+        $viewurl = $this->get_discussion_view_url_from_discussion_id($discussion->get_id());
+        if (null === $latestpost) {
+            return $viewurl;
+        } else {
+            return new moodle_url($viewurl, ['parent' => $latestpost]);
+        }
+    }
+
+    /**
+     * Get the url to view a discussion from a post.
+     *
+     * @param post_entity $post The post
+     * @return moodle_url
+     */
+    public function get_discussion_view_url_from_post(post_entity $post): moodle_url {
+        return $this->get_discussion_view_url_from_discussion_id($post->get_discussion_id());
+    }
+
+    /**
+     * Get the url to view a discussion from a discussion id and post id.
+     *
+     * @param int $discussionid The discussion id
+     * @param int $postid The post id
+     * @return moodle_url
+     */
+    public function get_view_post_url_from_post_id(int $discussionid, int $postid): moodle_url {
+        $url = $this->get_discussion_view_url_from_discussion_id($discussionid);
+        $url->set_anchor('p' . $postid);
+        return $url;
+    }
+
+    /**
+     * Get the url to view a post in the context of the rest of the discussion.
+     *
+     * @param post_entity $post The post
+     * @return moodle_url
+     */
+    public function get_view_post_url_from_post(post_entity $post): moodle_url {
+        return $this->get_view_post_url_from_post_id($post->get_discussion_id(), $post->get_id());
+    }
+
+    /**
+     * Get the url to view a post and it's replies in isolation without the rest of the
+     * discussion.
+     *
+     * @param int $discussionid The discussion id
+     * @param int $postid The post id
+     * @return moodle_url
+     */
+    public function get_view_isolated_post_url_from_post_id(int $discussionid, int $postid): moodle_url {
+        $url = $this->get_discussion_view_url_from_discussion_id($discussionid);
+        $url->params(['parent' => $postid]);
+        return $url;
+    }
+
+    /**
+     * Get the url to view a post and it's replies in isolation without the rest of the
+     * discussion.
+     *
+     * @param post_entity $post The post
+     * @return moodle_url
+     */
+    public function get_view_isolated_post_url_from_post(post_entity $post): moodle_url {
+        return $this->get_view_isolated_post_url_from_post_id($post->get_discussion_id(), $post->get_id());
+    }
+
+    /**
+     * Get the url to edit a post.
+     *
+     * @param forum_entity $forum The forum the post belongs to
+     * @param post_entity $post The post
+     * @return moodle_url
+     */
+    public function get_edit_post_url_from_post(forum_entity $forum, post_entity $post): moodle_url {
+        if ($forum->get_type() == 'single' && !$post->has_parent()) {
+            return new moodle_url('/course/modedit.php', [
+                'update' => $forum->get_course_module_record()->id,
+                'sesskey' => sesskey(),
+                'return' => 1
+            ]);
+        } else {
+            return new moodle_url('/mod/forum/post.php', [
+                'edit' => $post->get_id()
+            ]);
+        }
+    }
+
+    /**
+     * Get the url to split a discussion at a post.
+     *
+     * @param post_entity $post The post
+     * @return moodle_url
+     */
+    public function get_split_discussion_at_post_url_from_post(post_entity $post): moodle_url {
+        return new moodle_url('/mod/forum/post.php', [
+            'prune' => $post->get_id()
+        ]);
+    }
+
+    /**
+     * Get the url to delete a post.
+     *
+     * @param post_entity $post The post
+     * @return moodle_url
+     */
+    public function get_delete_post_url_from_post(post_entity $post): moodle_url {
+        return new moodle_url('/mod/forum/post.php', [
+            'delete' => $post->get_id()
+        ]);
+    }
+
+    /**
+     * Get the url to reply to a post.
+     *
+     * @param post_entity $post The post
+     * @return moodle_url
+     */
+    public function get_reply_to_post_url_from_post(post_entity $post): moodle_url {
+        return new moodle_url('/mod/forum/post.php#mformforum', [
+            'reply' => $post->get_id()
+        ]);
+    }
+
+    /**
+     * Get the url to export (see portfolios) a post.
+     *
+     * @param post_entity $post The post
+     * @return moodle_url
+     */
+    public function get_export_post_url_from_post(post_entity $post): ?moodle_url {
+        global $CFG;
+
+        require_once($CFG->libdir . '/portfoliolib.php');
+        $button = new \portfolio_add_button();
+        $button->set_callback_options('forum_portfolio_caller', ['postid' => $post->get_id()], 'mod_forum');
+        if ($post->has_attachments()) {
+            $button->set_formats(PORTFOLIO_FORMAT_RICHHTML);
+        } else {
+            $button->set_formats(PORTFOLIO_FORMAT_PLAINHTML);
+        }
+
+        $url = $button->to_html(PORTFOLIO_ADD_MOODLE_URL);
+        return $url ?: null;
+    }
+
+    /**
+     * Get the url to mark a post as read.
+     *
+     * @param post_entity $post The post
+     * @param int $displaymode The display mode to show the forum in after marking as read
+     * @return moodle_url
+     */
+    public function get_mark_post_as_read_url_from_post(post_entity $post, int $displaymode = FORUM_MODE_THREADED): moodle_url {
+        $params = [
+            'd' => $post->get_discussion_id(),
+            'postid' => $post->get_id(),
+            'mark' => 'read'
+        ];
+
+        $url = new moodle_url('/mod/forum/discuss.php', $params);
+
+        if ($displaymode == FORUM_MODE_THREADED) {
+            $url->param('parent', $post->get_parent_id());
+        } else {
+            $url->set_anchor('p' . $post->get_id());
+        }
+
+        return $url;
+    }
+
+    /**
+     * Get the url to mark a post as unread.
+     *
+     * @param post_entity $post The post
+     * @param int $displaymode The display mode to show the forum in after marking as unread
+     * @return moodle_url
+     */
+    public function get_mark_post_as_unread_url_from_post(post_entity $post, int $displaymode = FORUM_MODE_THREADED): moodle_url {
+        $params = [
+            'd' => $post->get_discussion_id(),
+            'postid' => $post->get_id(),
+            'mark' => 'unread'
+        ];
+
+        $url = new moodle_url('/mod/forum/discuss.php', $params);
+
+        if ($displaymode == FORUM_MODE_THREADED) {
+            $url->param('parent', $post->get_parent_id());
+        } else {
+            $url->set_anchor('p' . $post->get_id());
+        }
+
+        return $url;
+    }
+
+    /**
+     * Get the url to export attachments for a post.
+     *
+     * @param post_entity $post The post
+     * @param stored_file $attachment
+     * @return moodle_url|null
+     */
+    public function get_export_attachment_url_from_post_and_attachment(post_entity $post, stored_file $attachment): ?moodle_url {
+        global $CFG;
+
+        require_once($CFG->libdir . '/portfoliolib.php');
+        $button = new \portfolio_add_button();
+        $button->set_callback_options(
+            'forum_portfolio_caller',
+            ['postid' => $post->get_id(), 'attachment' => $attachment->get_id()],
+            'mod_forum'
+        );
+        $button->set_format_by_file($attachment);
+        $url = $button->to_html(PORTFOLIO_ADD_MOODLE_URL);
+        return $url ?: null;
+    }
+
+    /**
+     * Get the url to view an author's profile.
+     *
+     * @param author_entity $author The author
+     * @param int $courseid The course id
+     * @return moodle_url
+     */
+    public function get_author_profile_url(author_entity $author, int $courseid): moodle_url {
+        return new moodle_url('/user/view.php', [
+            'id' => $author->get_id(),
+            'course' => $courseid
+        ]);
+    }
+
+    /**
+     * Get the url to view the author's profile image. The author's context id should be
+     * provided to prevent the code from needing to load it.
+     *
+     * @param author_entity $author The author
+     * @param int|null $authorcontextid The author context id
+     * @param int $size The size of the image to return
+     * @return moodle_url
+     */
+    public function get_author_profile_image_url(
+        author_entity $author,
+        int $authorcontextid = null,
+        int $size = 100
+    ): moodle_url {
+        global $PAGE;
+
+        $datamapper = $this->legacydatamapperfactory->get_author_data_mapper();
+        $record = $datamapper->to_legacy_object($author);
+        $record->contextid = $authorcontextid;
+        $userpicture = new user_picture($record);
+        $userpicture->size = $size;
+
+        return $userpicture->get_url($PAGE);
+    }
+
+    /**
+     * Get the url to view an author's group.
+     *
+     * @param \stdClass $group The group
+     * @return moodle_url
+     */
+    public function get_author_group_url(\stdClass $group): moodle_url {
+        return new moodle_url('/user/index.php', [
+                'id' => $group->courseid,
+                'group' => $group->id
+        ]);
+    }
+    /**
+     * Get the url to mark a discussion as read.
+     *
+     * @param forum_entity $forum The forum that the discussion belongs to
+     * @param discussion_entity $discussion The discussion
+     * @return moodle_url
+     */
+    public function get_mark_discussion_as_read_url_from_discussion(
+        forum_entity $forum,
+        discussion_entity $discussion
+    ): moodle_url {
+        return new moodle_url('/mod/forum/markposts.php', [
+            'f' => $discussion->get_forum_id(),
+            'd' => $discussion->get_id(),
+            'mark' => 'read',
+            'sesskey' => sesskey(),
+            'return' => $this->get_forum_view_url_from_forum($forum)->out(),
+        ]);
+    }
+
+    /**
+     * Get the url to mark all discussions as read.
+     *
+     * @param forum_entity $forum The forum that the discussions belong to
+     * @return moodle_url
+     */
+    public function get_mark_all_discussions_as_read_url(forum_entity $forum): moodle_url {
+        return new moodle_url('/mod/forum/markposts.php', [
+            'f' => $forum->get_id(),
+            'mark' => 'read',
+            'sesskey' => sesskey(),
+            'return' => $this->get_forum_view_url_from_forum($forum)->out(),
+        ]);
+    }
+
+    /**
+     * Get the url to subscribe to a discussion.
+     *
+     * @param discussion_entity $discussion The discussion
+     * @return moodle_url
+     */
+    public function get_discussion_subscribe_url(discussion_entity $discussion): moodle_url {
+        return new moodle_url('/mod/forum/subscribe.php', [
+            'sesskey' => sesskey(),
+            'id' => $discussion->get_forum_id(),
+            'd' => $discussion->get_id()
+        ]);
+    }
+
+    /**
+     * Generate the pinned discussion link
+     *
+     * @param discussion_entity $discussion
+     * @return moodle_url
+     * @throws \moodle_exception
+     */
+    public function get_pin_discussion_url_from_discussion(discussion_entity $discussion): moodle_url {
+        return new moodle_url('discuss.php', [
+            'sesskey' => sesskey(),
+            'd' => $discussion->get_id(),
+            'pin' => $discussion->is_pinned() ? FORUM_DISCUSSION_UNPINNED : FORUM_DISCUSSION_PINNED
+        ]);
+    }
+}

mod/forum/classes/local/factories/vault.php

@@ -0,0 +1,163 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Vault factory.
+ *
+ * @package    mod_forum
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_forum\local\factories;
+
+defined('MOODLE_INTERNAL') || die();
+
+use mod_forum\local\factories\entity as entity_factory;
+use mod_forum\local\vaults\author as author_vault;
+use mod_forum\local\vaults\discussion as discussion_vault;
+use mod_forum\local\vaults\discussion_list as discussion_list_vault;
+use mod_forum\local\vaults\forum as forum_vault;
+use mod_forum\local\vaults\post as post_vault;
+use mod_forum\local\vaults\post_attachment as post_attachment_vault;
+use mod_forum\local\vaults\post_read_receipt_collection as post_read_receipt_collection_vault;
+use file_storage;
+use moodle_database;
+
+/**
+ * Vault factory.
+ *
+ * See:
+ * https://designpatternsphp.readthedocs.io/en/latest/Creational/SimpleFactory/README.html
+ *
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class vault {
+    /** @var entity_factory $entityfactory Entity factory */
+    private $entityfactory;
+    /** @var legacy_data_mapper $legacymapper Entity factory */
+    private $legacymapper;
+    /** @var moodle_database $db A moodle database */
+    private $db;
+    /** @var file_storage $filestorage A file storage instance */
+    private $filestorage;
+
+    /**
+     * Constructor.
+     *
+     * @param moodle_database $db A moodle database
+     * @param entity_factory $entityfactory Entity factory
+     * @param file_storage $filestorage A file storage instance
+     * @param legacy_data_mapper $legacyfactory Datamapper
+     */
+    public function __construct(moodle_database $db, entity_factory $entityfactory,
+        file_storage $filestorage, legacy_data_mapper $legacyfactory) {
+        $this->db = $db;
+        $this->entityfactory = $entityfactory;
+        $this->filestorage = $filestorage;
+        $this->legacymapper = $legacyfactory;
+    }
+
+    /**
+     * Create a forum vault.
+     *
+     * @return forum_vault
+     */
+    public function get_forum_vault(): forum_vault {
+        return new forum_vault(
+            $this->db,
+            $this->entityfactory,
+            $this->legacymapper->get_legacy_data_mapper_for_vault('forum')
+        );
+    }
+
+    /**
+     * Create a discussion vault.
+     *
+     * @return discussion_vault
+     */
+    public function get_discussion_vault(): discussion_vault {
+        return new discussion_vault(
+            $this->db,
+            $this->entityfactory,
+            $this->legacymapper->get_legacy_data_mapper_for_vault('discussion')
+        );
+    }
+
+    /**
+     * Create a discussion list vault.
+     *
+     * @return discussion_list_vault
+     */
+    public function get_discussions_in_forum_vault(): discussion_list_vault {
+        return new discussion_list_vault(
+            $this->db,
+            $this->entityfactory,
+            $this->legacymapper->get_legacy_data_mapper_for_vault('discussion')
+        );
+    }
+
+    /**
+     * Create a post vault.
+     *
+     * @return post_vault
+     */
+    public function get_post_vault(): post_vault {
+        return new post_vault(
+            $this->db,
+            $this->entityfactory,
+            $this->legacymapper->get_legacy_data_mapper_for_vault('post')
+        );
+    }
+
+    /**
+     * Create an author vault.
+     *
+     * @return author_vault
+     */
+    public function get_author_vault(): author_vault {
+        return new author_vault(
+            $this->db,
+            $this->entityfactory,
+            $this->legacymapper->get_legacy_data_mapper_for_vault('author')
+        );
+    }
+
+    /**
+     * Create a post read receipt collection vault.
+     *
+     * @return post_read_receipt_collection_vault
+     */
+    public function get_post_read_receipt_collection_vault(): post_read_receipt_collection_vault {
+        return new post_read_receipt_collection_vault(
+            $this->db,
+            $this->entityfactory,
+            $this->legacymapper->get_legacy_data_mapper_for_vault('post')
+        );
+    }
+
+    /**
+     * Create a post attachment vault.
+     *
+     * @return post_attachment_vault
+     */
+    public function get_post_attachment_vault(): post_attachment_vault {
+        return new post_attachment_vault(
+            $this->filestorage
+        );
+    }
+}

mod/forum/classes/local/managers/capability.php

@@ -0,0 +1,732 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Capability manager for the forum.
+ *
+ * @package    mod_forum
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_forum\local\managers;
+
+defined('MOODLE_INTERNAL') || die();
+
+use mod_forum\local\data_mappers\legacy\forum as legacy_forum_data_mapper;
+use mod_forum\local\data_mappers\legacy\discussion as legacy_discussion_data_mapper;
+use mod_forum\local\data_mappers\legacy\post as legacy_post_data_mapper;
+use mod_forum\local\entities\discussion as discussion_entity;
+use mod_forum\local\entities\forum as forum_entity;
+use mod_forum\local\entities\post as post_entity;
+use mod_forum\subscriptions;
+use context;
+use context_system;
+use stdClass;
+use moodle_exception;
+
+require_once($CFG->dirroot . '/mod/forum/lib.php');
+
+/**
+ * Capability manager for the forum.
+ *
+ * Defines all the business rules for what a user can and can't do in the forum.
+ *
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class capability {
+    /** @var legacy_forum_data_mapper $forumdatamapper Legacy forum data mapper */
+    private $forumdatamapper;
+    /** @var legacy_discussion_data_mapper $discussiondatamapper Legacy discussion data mapper */
+    private $discussiondatamapper;
+    /** @var legacy_post_data_mapper $postdatamapper Legacy post data mapper */
+    private $postdatamapper;
+    /** @var forum_entity $forum Forum entity */
+    private $forum;
+    /** @var stdClass $forumrecord Legacy forum record */
+    private $forumrecord;
+    /** @var context $context Module context for the forum */
+    private $context;
+    /** @var array $canviewpostcache Cache of discussion posts that can be viewed by a user. */
+    protected $canviewpostcache = [];
+
+    /**
+     * Constructor.
+     *
+     * @param forum_entity $forum The forum entity to manage capabilities for.
+     * @param legacy_forum_data_mapper $forumdatamapper Legacy forum data mapper
+     * @param legacy_discussion_data_mapper $discussiondatamapper Legacy discussion data mapper
+     * @param legacy_post_data_mapper $postdatamapper Legacy post data mapper
+     */
+    public function __construct(
+        forum_entity $forum,
+        legacy_forum_data_mapper $forumdatamapper,
+        legacy_discussion_data_mapper $discussiondatamapper,
+        legacy_post_data_mapper $postdatamapper
+    ) {
+        $this->forumdatamapper = $forumdatamapper;
+        $this->discussiondatamapper = $discussiondatamapper;
+        $this->postdatamapper = $postdatamapper;
+        $this->forum = $forum;
+        $this->forumrecord = $forumdatamapper->to_legacy_object($forum);
+        $this->context = $forum->get_context();
+    }
+
+    /**
+     * Can the user subscribe to this forum?
+     *
+     * @param stdClass $user The user to check
+     * @return bool
+     */
+    public function can_subscribe_to_forum(stdClass $user): bool {
+        if ($this->forum->get_type() == 'single') {
+            return false;
+        }
+
+        return !is_guest($this->get_context(), $user) &&
+            subscriptions::is_subscribable($this->get_forum_record());
+    }
+
+    /**
+     * Can the user create discussions in this forum?
+     *
+     * @param stdClass $user The user to check
+     * @param int|null $groupid The current activity group id
+     * @return bool
+     */
+    public function can_create_discussions(stdClass $user, int $groupid = null): bool {
+        if (isguestuser($user) or !isloggedin()) {
+            return false;
+        }
+
+        if ($this->forum->is_cutoff_date_reached()) {
+            if (!has_capability('mod/forum:canoverridecutoff', $this->get_context())) {
+                return false;
+            }
+        }
+
+        // If the user reaches the number of posts equal to warning/blocking setting then return the value of canpost in $warningobj.
+        $cmrecord = $this->forum->get_course_module_record();
+        if ($warningobj = forum_check_throttling($this->forumrecord, $cmrecord)) {
+            return $warningobj->canpost;
+        }
+
+        switch ($this->forum->get_type()) {
+            case 'news':
+                $capability = 'mod/forum:addnews';
+                break;
+            case 'qanda':
+                $capability = 'mod/forum:addquestion';
+                break;
+            default:
+                $capability = 'mod/forum:startdiscussion';
+        }
+
+        if (!has_capability($capability, $this->forum->get_context(), $user)) {
+            return false;
+        }
+
+        if ($this->forum->get_type() == 'eachuser') {
+            if (forum_user_has_posted_discussion($this->forum->get_id(), $user->id, $groupid)) {
+                return false;
+            }
+        }
+
+        if ($this->forum->is_in_group_mode()) {
+            return $groupid ? $this->can_access_group($user, $groupid) : $this->can_access_all_groups($user);
+        } else {
+            return true;
+        }
+    }
+
+    /**
+     * Can the user access all groups?
+     *
+     * @param stdClass $user The user to check
+     * @return bool
+     */
+    public function can_access_all_groups(stdClass $user): bool {
+        return has_capability('moodle/site:accessallgroups', $this->get_context(), $user);
+    }
+
+    /**
+     * Can the user access the given group?
+     *
+     * @param stdClass $user The user to check
+     * @param int $groupid The id of the group that the forum is set to
+     * @return bool
+     */
+    public function can_access_group(stdClass $user, int $groupid): bool {
+        if ($this->can_access_all_groups($user)) {
+            // This user has access to all groups.
+            return true;
+        }
+
+        // This is a group discussion for a forum in separate groups mode.
+        // Check if the user is a member.
+        // This is the most expensive check.
+        return groups_is_member($groupid, $user->id);
+    }
+
+    /**
+     * Can the user post to their groups?
+     *
+     * @param stdClass $user The user to check
+     * @return bool
+     */
+    public function can_post_to_my_groups(stdClass $user): bool {
+        return has_capability('mod/forum:canposttomygroups', $this->get_context(), $user);
+    }
+
+    /**
+     * Can the user view discussions in this forum?
+     *
+     * @param stdClass $user The user to check
+     * @return bool
+     */
+    public function can_view_discussions(stdClass $user): bool {
+        return has_capability('mod/forum:viewdiscussion', $this->get_context(), $user);
+    }
+
+    /**
+     * Can the user move discussions in this forum?
+     *
+     * @param stdClass $user The user to check
+     * @return bool
+     */
+    public function can_move_discussions(stdClass $user): bool {
+        $forum = $this->get_forum();
+        return $forum->get_type() !== 'single' &&
+                has_capability('mod/forum:movediscussions', $this->get_context(), $user);
+    }
+
+    /**
+     * Can the user pin discussions in this forum?
+     *
+     * @param stdClass $user The user to check
+     * @return bool
+     */
+    public function can_pin_discussions(stdClass $user): bool {
+        return $this->forum->get_type() !== 'single' &&
+                has_capability('mod/forum:pindiscussions', $this->get_context(), $user);
+    }
+
+    /**
+     * Can the user split discussions in this forum?
+     *
+     * @param stdClass $user The user to check
+     * @return bool
+     */
+    public function can_split_discussions(stdClass $user): bool {
+        $forum = $this->get_forum();
+        return $forum->get_type() !== 'single' && has_capability('mod/forum:splitdiscussions', $this->get_context(), $user);
+    }
+
+    /**
+     * Can the user export (see portfolios) discussions in this forum?
+     *
+     * @param stdClass $user The user to check
+     * @return bool
+     */
+    public function can_export_discussions(stdClass $user): bool {
+        global $CFG;
+        return $CFG->enableportfolios && has_capability('mod/forum:exportdiscussion', $this->get_context(), $user);
+    }
+
+    /**
+     * Can the user manually mark posts as read/unread in this forum?
+     *
+     * @param stdClass $user The user to check
+     * @return bool
+     */
+    public function can_manually_control_post_read_status(stdClass $user): bool {
+        global $CFG;
+        return $CFG->forum_usermarksread && isloggedin() && forum_tp_is_tracked($this->get_forum_record(), $user);
+    }
+
+    /**
+     * Is the user required to post in the discussion before they can view it?
+     *
+     * @param stdClass $user The user to check
+     * @param discussion_entity $discussion The discussion to check
+     * @return bool
+     */
+    public function must_post_before_viewing_discussion(stdClass $user, discussion_entity $discussion): bool {
+        $forum = $this->get_forum();
+
+        if ($forum->get_type() === 'qanda') {
+            // If it's a Q and A forum then the user must either have the capability to view without
+            // posting or the user must have posted before they can view the discussion.
+            return !has_capability('mod/forum:viewqandawithoutposting', $this->get_context(), $user) &&
+                !forum_user_has_posted($forum->get_id(), $discussion->get_id(), $user->id);
+        } else {
+            // No other forum types require posting before viewing.
+            return false;
+        }
+    }
+
+    /**
+     * Can the user subscribe to the give discussion?
+     *
+     * @param stdClass $user The user to check
+     * @param discussion_entity $discussion The discussion to check
+     * @return bool
+     */
+    public function can_subscribe_to_discussion(stdClass $user, discussion_entity $discussion): bool {
+        return $this->can_subscribe_to_forum($user);
+    }
+
+    /**
+     * Can the user move the discussion in this forum?
+     *
+     * @param stdClass $user The user to check
+     * @param discussion_entity $discussion The discussion to check
+     * @return bool
+     */
+    public function can_move_discussion(stdClass $user, discussion_entity $discussion): bool {
+        return $this->can_move_discussions($user);
+    }
+
+    /**
+     * Is the user pin the discussion?
+     *
+     * @param stdClass $user The user to check
+     * @param discussion_entity $discussion The discussion to check
+     * @return bool
+     */
+    public function can_pin_discussion(stdClass $user, discussion_entity $discussion): bool {
+        return $this->can_pin_discussions($user);
+    }
+
+    /**
+     * Can the user post in this discussion?
+     *
+     * @param stdClass $user The user to check
+     * @param discussion_entity $discussion The discussion to check
+     * @return bool
+     */
+    public function can_post_in_discussion(stdClass $user, discussion_entity $discussion): bool {
+        $forum = $this->get_forum();
+        $forumrecord = $this->get_forum_record();
+
+        $discussionrecord = $this->get_discussion_record($discussion);
+        $context = $this->get_context();
+        $coursemodule = $forum->get_course_module_record();
+        $course = $forum->get_course_record();
+
+        $status = forum_user_can_post($forumrecord, $discussionrecord, $user, $coursemodule, $course, $context);
+
+        // If the user reaches the number of posts equal to warning/blocking setting then logically and canpost value with $status.
+        if ($warningobj = forum_check_throttling($forumrecord, $coursemodule)) {
+            return $status && $warningobj->canpost;
+        }
+        return $status;
+    }
+
+    /**
+     * Can the user favourite the discussion
+     *
+     * @param stdClass $user The user to check
+     * @return bool
+     */
+    public function can_favourite_discussion(stdClass $user): bool {
+        $context = $this->get_context();
+        return has_capability('mod/forum:cantogglefavourite', $context, $user);
+    }
+
+    /**
+     * Can the user view the content of a discussion?
+     *
+     * @param stdClass $user The user to check
+     * @param discussion_entity $discussion The discussion to check
+     * @return bool
+     */
+    public function can_view_discussion(stdClass $user, discussion_entity $discussion): bool {
+        $forumrecord = $this->get_forum_record();
+        $discussionrecord = $this->get_discussion_record($discussion);
+        $context = $this->get_context();
+
+        return forum_user_can_see_discussion($forumrecord, $discussionrecord, $context, $user);
+    }
+
+    /**
+     * Can the user view the content of the post in this discussion?
+     *
+     * @param stdClass $user The user to check
+     * @param discussion_entity $discussion The discussion to check
+     * @param post_entity $post The post the user wants to view
+     * @return bool
+     */
+    public function can_view_post(stdClass $user, discussion_entity $discussion, post_entity $post): bool {
+        if (!$this->can_view_post_shell($user, $post)) {
+            return false;
+        }
+
+        // Return cached can view if possible.
+        if (isset($this->canviewpostcache[$user->id][$post->get_id()])) {
+            return $this->canviewpostcache[$user->id][$post->get_id()];
+        }
+
+        // Otherwise, check if the user can see this post.
+        $forum = $this->get_forum();
+        $forumrecord = $this->get_forum_record();
+        $discussionrecord = $this->get_discussion_record($discussion);
+        $postrecord = $this->get_post_record($post);
+        $coursemodule = $forum->get_course_module_record();
+        $canviewpost = forum_user_can_see_post($forumrecord, $discussionrecord, $postrecord, $user, $coursemodule, false);
+
+        // Then cache the result before returning.
+        $this->canviewpostcache[$user->id][$post->get_id()] = $canviewpost;
+
+        return $canviewpost;
+    }
+
+    /**
+     * Can the user view the post at all?
+     * In some situations the user can view the shell of a post without being able to view its content.
+     *
+     * @param   stdClass $user The user to check
+     * @param   post_entity $post The post the user wants to view
+     * @return  bool
+     *
+     */
+    public function can_view_post_shell(stdClass $user, post_entity $post): bool {
+        if ($post->is_owned_by_user($user)) {
+            return true;
+        }
+
+        if (!$post->is_private_reply()) {
+            return true;
+        }
+
+        if ($post->is_private_reply_intended_for_user($user)) {
+            return true;
+        }
+
+        return $this->can_view_any_private_reply($user);
+    }
+
+    /**
+     * Whether the user can view any private reply in the forum.
+     *
+     * @param   stdClass $user The user to check
+     * @return  bool
+     */
+    public function can_view_any_private_reply(stdClass $user): bool {
+        return has_capability('mod/forum:readprivatereplies', $this->get_context(), $user);
+    }
+
+    /**
+     * Can the user edit the post in this discussion?
+     *
+     * @param stdClass $user The user to check
+     * @param discussion_entity $discussion The discussion to check
+     * @param post_entity $post The post the user wants to edit
+     * @return bool
+     */
+    public function can_edit_post(stdClass $user, discussion_entity $discussion, post_entity $post): bool {
+        global $CFG;
+
+        $context = $this->get_context();
+        $ownpost = $post->is_owned_by_user($user);
+        $ineditingtime = $post->get_age() < $CFG->maxeditingtime;
+        $mailnow = $post->should_mail_now();
+
+        switch ($this->forum->get_type()) {
+            case 'news':
+                // Allow editing of news posts once the discussion has started.
+                $ineditingtime = !$post->has_parent() && $discussion->has_started();
+                break;
+            case 'single':
+                if ($discussion->is_first_post($post)) {
+                    return has_capability('moodle/course:manageactivities', $context, $user);
+                }
+                break;
+        }
+
+        return ($ownpost && $ineditingtime && !$mailnow) || has_capability('mod/forum:editanypost', $context, $user);
+    }
+
+    /**
+     * Verifies is the given user can delete a post.
+     *
+     * @param stdClass $user The user to check
+     * @param discussion_entity $discussion The discussion to check
+     * @param post_entity $post The post the user wants to delete
+     * @param bool $hasreplies Whether the post has replies
+     * @return bool
+     * @throws moodle_exception
+     */
+    public function validate_delete_post(stdClass $user, discussion_entity $discussion, post_entity $post,
+            bool $hasreplies = false): void {
+        global $CFG;
+
+        $forum = $this->get_forum();
+
+        if ($forum->get_type() == 'single' && $discussion->is_first_post($post)) {
+            // Do not allow deleting of first post in single simple type.
+            throw new moodle_exception('cannotdeletepost', 'forum');
+        }
+
+        $context = $this->get_context();
+        $ownpost = $post->is_owned_by_user($user);
+        $ineditingtime = $post->get_age() < $CFG->maxeditingtime;
+        $mailnow = $post->should_mail_now();
+
+        if (!($ownpost && $ineditingtime && has_capability('mod/forum:deleteownpost', $context, $user) && !$mailnow ||
+                has_capability('mod/forum:deleteanypost', $context, $user))) {
+
+            throw new moodle_exception('cannotdeletepost', 'forum');
+        }
+
+        if ($post->get_total_score()) {
+            throw new moodle_exception('couldnotdeleteratings', 'rating');
+        }
+
+        if ($hasreplies && !has_capability('mod/forum:deleteanypost', $context, $user)) {
+            throw new moodle_exception('couldnotdeletereplies', 'forum');
+        }
+    }
+
+
+    /**
+     * Can the user delete the post in this discussion?
+     *
+     * @param stdClass $user The user to check
+     * @param discussion_entity $discussion The discussion to check
+     * @param post_entity $post The post the user wants to delete
+     * @param bool $hasreplies Whether the post has replies
+     * @return bool
+     */
+    public function can_delete_post(stdClass $user, discussion_entity $discussion, post_entity $post,
+            bool $hasreplies = false): bool {
+
+        try {
+            $this->validate_delete_post($user, $discussion, $post, $hasreplies);
+            return true;
+        } catch (moodle_exception $e) {
+            return false;
+        }
+    }
+
+    /**
+     * Can the user split the post in this discussion?
+     *
+     * @param stdClass $user The user to check
+     * @param discussion_entity $discussion The discussion to check
+     * @param post_entity $post The post the user wants to split
+     * @return bool
+     */
+    public function can_split_post(stdClass $user, discussion_entity $discussion, post_entity $post): bool {
+        if ($post->is_private_reply()) {
+            // It is not possible to create a private discussion.
+            return false;
+        }
+
+        return $this->can_split_discussions($user) && $post->has_parent();
+    }
+
+    /**
+     * Can the user reply to the post in this discussion?
+     *
+     * @param stdClass $user The user to check
+     * @param discussion_entity $discussion The discussion to check
+     * @param post_entity $post The post the user wants to reply to
+     * @return bool
+     */
+    public function can_reply_to_post(stdClass $user, discussion_entity $discussion, post_entity $post): bool {
+        if ($post->is_private_reply()) {
+            // It is not possible to reply to a private reply.
+            return false;
+        } else if (!$this->can_view_post($user, $discussion, $post)) {
+            // If the user cannot view the post in the first place, the user should not be able to reply to the post.
+            return false;
+        }
+
+        return $this->can_post_in_discussion($user, $discussion);
+    }
+
+    /**
+     * Can the user reply privately to the specified post?
+     *
+     * @param stdClass $user The user to check
+     * @param post_entity $post The post the user wants to reply to
+     * @return bool
+     */
+    public function can_reply_privately_to_post(stdClass $user, post_entity $post): bool {
+        if ($post->is_private_reply()) {
+            // You cannot reply privately to a post which is, itself, a private reply.
+            return false;
+        }
+
+        return has_capability('mod/forum:postprivatereply', $this->get_context(), $user);
+    }
+
+    /**
+     * Can the user export (see portfolios) the post in this discussion?
+     *
+     * @param stdClass $user The user to check
+     * @param post_entity $post The post the user wants to export
+     * @return bool
+     */
+    public function can_export_post(stdClass $user, post_entity $post): bool {
+        global $CFG;
+        $context = $this->get_context();
+        return $CFG->enableportfolios  && (has_capability('mod/forum:exportpost', $context, $user) ||
+            ($post->is_owned_by_user($user) && has_capability('mod/forum:exportownpost', $context, $user)));
+    }
+
+    /**
+     * Get the forum entity for this capability manager.
+     *
+     * @return forum_entity
+     */
+    protected function get_forum(): forum_entity {
+        return $this->forum;
+    }
+
+    /**
+     * Get the legacy forum record for this forum.
+     *
+     * @return stdClass
+     */
+    protected function get_forum_record(): stdClass {
+        return $this->forumrecord;
+    }
+
+    /**
+     * Get the context for this capability manager.
+     *
+     * @return context
+     */
+    protected function get_context(): context {
+        return $this->context;
+    }
+
+    /**
+     * Get the legacy discussion record for the given discussion entity.
+     *
+     * @param discussion_entity $discussion The discussion to convert
+     * @return stdClass
+     */
+    protected function get_discussion_record(discussion_entity $discussion): stdClass {
+        return $this->discussiondatamapper->to_legacy_object($discussion);
+    }
+
+    /**
+     * Get the legacy post record for the given post entity.
+     *
+     * @param post_entity $post The post to convert
+     * @return stdClass
+     */
+    protected function get_post_record(post_entity $post): stdClass {
+        return $this->postdatamapper->to_legacy_object($post);
+    }
+
+    /**
+     * Can the user view the participants of this discussion?
+     *
+     * @param stdClass $user The user to check
+     * @param discussion_entity $discussion The discussion to check
+     * @return bool
+     */
+    public function can_view_participants(stdClass $user, discussion_entity $discussion): bool {
+        return course_can_view_participants($this->get_context()) &&
+            !$this->must_post_before_viewing_discussion($user, $discussion);
+    }
+
+    /**
+     * Can the user view hidden posts in this forum?
+     *
+     * @param stdClass $user The user to check
+     * @return bool
+     */
+    public function can_view_hidden_posts(stdClass $user): bool {
+        return has_capability('mod/forum:viewhiddentimedposts', $this->get_context(), $user);
+    }
+
+    /**
+     * Can the user manage this forum?
+     *
+     * @param stdClass $user The user to check
+     * @return bool
+     */
+    public function can_manage_forum(stdClass $user) {
+        return has_capability('moodle/course:manageactivities', $this->get_context(), $user);
+    }
+
+    /**
+     * Can the user manage tags on the site?
+     *
+     * @param stdClass $user The user to check
+     * @return bool
+     */
+    public function can_manage_tags(stdClass $user): bool {
+        return has_capability('moodle/tag:manage', context_system::instance(), $user);
+    }
+
+    /**
+     * Checks whether the user can self enrol into the course.
+     * Mimics the checks on the add button in deprecatedlib/forum_print_latest_discussions
+     *
+     * @param stdClass $user
+     * @return bool
+     */
+    public function can_self_enrol(stdClass $user): bool {
+        $canstart = false;
+
+        if ($this->forum->get_type() != 'news') {
+            if (isguestuser($user) or !isloggedin()) {
+                $canstart = true;
+            }
+
+            if (!is_enrolled($this->context) and !is_viewing($this->context)) {
+                 // Allow guests and not-logged-in to see the button - they are prompted to log in after clicking the link,
+                 // Normal users with temporary guest access see this button too, they are asked to enrol instead,
+                 // Do not show the button to users with suspended enrolments here.
+                $canstart = enrol_selfenrol_available($this->forum->get_course_id());
+            }
+        }
+
+        return $canstart;
+    }
+
+    /**
+     * Checks whether the user can export the whole forum (discussions and posts).
+     *
+     * @param stdClass $user The user object.
+     * @return bool True if the user can export the forum or false otherwise.
+     */
+    public function can_export_forum(stdClass $user): bool {
+        return has_capability('mod/forum:exportforum', $this->get_context(), $user);
+    }
+
+    /**
+     * Check whether the supplied grader can grade the gradee.
+     *
+     * @param stdClass $grader The user grading
+     * @param stdClass $gradee The user being graded
+     * @return bool
+     */
+    public function can_grade(stdClass $grader, stdClass $gradee = null): bool {
+        if (!has_capability('mod/forum:grade', $this->get_context(), $grader)) {
+            return false;
+        }
+
+        return true;
+    }
+}

mod/forum/classes/local/renderers/discussion.php

@@ -0,0 +1,461 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Discussion renderer.
+ *
+ * @package    mod_forum
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_forum\local\renderers;
+
+defined('MOODLE_INTERNAL') || die();
+
+use mod_forum\local\entities\discussion as discussion_entity;
+use mod_forum\local\entities\forum as forum_entity;
+use mod_forum\local\entities\post as post_entity;
+use mod_forum\local\entities\sorter as sorter_entity;
+use mod_forum\local\factories\entity as entity_factory;
+use mod_forum\local\factories\legacy_data_mapper as legacy_data_mapper_factory;
+use mod_forum\local\factories\exporter as exporter_factory;
+use mod_forum\local\factories\url as url_factory;
+use mod_forum\local\factories\vault as vault_factory;
+use mod_forum\local\managers\capability as capability_manager;
+use mod_forum\local\renderers\posts as posts_renderer;
+use forum_portfolio_caller;
+use core\output\notification;
+use context;
+use context_module;
+use html_writer;
+use moodle_exception;
+use moodle_page;
+use moodle_url;
+use rating_manager;
+use renderer_base;
+use single_button;
+use single_select;
+use stdClass;
+use url_select;
+
+require_once($CFG->dirroot . '/mod/forum/lib.php');
+require_once($CFG->dirroot . '/mod/forum/locallib.php');
+
+/**
+ * Discussion renderer class.
+ *
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class discussion {
+    /** @var forum_entity $forum The forum that the discussion belongs to */
+    private $forum;
+    /** @var discussion_entity $discussion The discussion entity */
+    private $discussion;
+    /** @var stdClass $discussionrecord Legacy discussion record */
+    private $discussionrecord;
+    /** @var stdClass $forumrecord Legacy forum record */
+    private $forumrecord;
+    /** @var int $displaymode The display mode to render the discussion in */
+    private $displaymode;
+    /** @var renderer_base $renderer Renderer base */
+    private $renderer;
+    /** @var posts_renderer $postsrenderer A posts renderer */
+    private $postsrenderer;
+    /** @var moodle_page $page The page this discussion is being rendered for */
+    private $page;
+    /** @var legacy_data_mapper_factory $legacydatamapperfactory Legacy data mapper factory */
+    private $legacydatamapperfactory;
+    /** @var exporter_factory $exporterfactory Exporter factory */
+    private $exporterfactory;
+    /** @var vault_factory $vaultfactory Vault factory */
+    private $vaultfactory;
+    /** @var url_factory $urlfactory URL factory */
+    private $urlfactory;
+    /** @var entity_factory $entityfactory Entity factory */
+    private $entityfactory;
+    /** @var capability_manager $capabilitymanager Capability manager */
+    private $capabilitymanager;
+    /** @var rating_manager $ratingmanager Rating manager */
+    private $ratingmanager;
+    /** @var moodle_url $baseurl The base URL for the discussion */
+    private $baseurl;
+    /** @var array $notifications List of HTML notifications to display */
+    private $notifications;
+    /** @var sorter_entity $exportedpostsorter Sorter for the exported posts */
+    private $exportedpostsorter;
+    /** @var callable $postprocessfortemplate Function to process exported posts before template rendering */
+    private $postprocessfortemplate;
+
+    /**
+     * Constructor.
+     *
+     * @param forum_entity $forum The forum that the discussion belongs to
+     * @param discussion_entity $discussion The discussion entity
+     * @param int $displaymode The display mode to render the discussion in
+     * @param renderer_base $renderer Renderer base
+     * @param posts_renderer $postsrenderer A posts renderer
+     * @param moodle_page $page The page this discussion is being rendered for
+     * @param legacy_data_mapper_factory $legacydatamapperfactory Legacy data mapper factory
+     * @param exporter_factory $exporterfactory Exporter factory
+     * @param vault_factory $vaultfactory Vault factory
+     * @param url_factory $urlfactory URL factory
+     * @param entity_factory $entityfactory Entity factory
+     * @param capability_manager $capabilitymanager Capability manager
+     * @param rating_manager $ratingmanager Rating manager
+     * @param sorter_entity $exportedpostsorter Sorter for the exported posts
+     * @param moodle_url $baseurl The base URL for the discussion
+     * @param array $notifications List of HTML notifications to display
+     * @param callable|null $postprocessfortemplate Post processing for template callback
+     */
+    public function __construct(
+        forum_entity $forum,
+        discussion_entity $discussion,
+        int $displaymode,
+        renderer_base $renderer,
+        posts_renderer $postsrenderer,
+        moodle_page $page,
+        legacy_data_mapper_factory $legacydatamapperfactory,
+        exporter_factory $exporterfactory,
+        vault_factory $vaultfactory,
+        url_factory $urlfactory,
+        entity_factory $entityfactory,
+        capability_manager $capabilitymanager,
+        rating_manager $ratingmanager,
+        sorter_entity $exportedpostsorter,
+        moodle_url $baseurl,
+        array $notifications = [],
+        callable $postprocessfortemplate = null
+    ) {
+        $this->forum = $forum;
+        $this->discussion = $discussion;
+        $this->displaymode = $displaymode;
+        $this->renderer = $renderer;
+        $this->postsrenderer = $postsrenderer;
+        $this->page = $page;
+        $this->baseurl = $baseurl;
+        $this->legacydatamapperfactory = $legacydatamapperfactory;
+        $this->exporterfactory = $exporterfactory;
+        $this->vaultfactory = $vaultfactory;
+        $this->urlfactory = $urlfactory;
+        $this->entityfactory = $entityfactory;
+        $this->capabilitymanager = $capabilitymanager;
+        $this->ratingmanager = $ratingmanager;
+        $this->notifications = $notifications;
+
+        $this->exportedpostsorter = $exportedpostsorter;
+        $this->postprocessfortemplate = $postprocessfortemplate;
+
+        $forumdatamapper = $this->legacydatamapperfactory->get_forum_data_mapper();
+        $this->forumrecord = $forumdatamapper->to_legacy_object($forum);
+
+        $discussiondatamapper = $this->legacydatamapperfactory->get_discussion_data_mapper();
+        $this->discussionrecord = $discussiondatamapper->to_legacy_object($discussion);
+    }
+
+    /**
+     * Render the discussion for the given user in the specified display mode.
+     *
+     * @param stdClass $user The user viewing the discussion
+     * @param post_entity $firstpost The first post in the discussion
+     * @param array $replies List of replies to the first post
+     * @return string HTML for the discussion
+     */
+    public function render(
+        stdClass $user,
+        post_entity $firstpost,
+        array $replies
+    ): string {
+        global $CFG;
+
+        $displaymode = $this->displaymode;
+        $capabilitymanager = $this->capabilitymanager;
+        $urlfactory = $this->urlfactory;
+        $entityfactory = $this->entityfactory;
+
+        // Make sure we can render.
+        if (!$capabilitymanager->can_view_discussions($user)) {
+            throw new moodle_exception('noviewdiscussionspermission', 'mod_forum');
+        }
+
+        $posts = array_merge([$firstpost], array_values($replies));
+
+        if ($this->postprocessfortemplate !== null) {
+            $exporteddiscussion = ($this->postprocessfortemplate) ($this->discussion, $user, $this->forum);
+        } else {
+            $exporteddiscussion = $this->get_exported_discussion($user);
+        }
+
+        $hasanyactions = false;
+        $hasanyactions = $hasanyactions || $capabilitymanager->can_favourite_discussion($user);
+        $hasanyactions = $hasanyactions || $capabilitymanager->can_pin_discussions($user);
+        $hasanyactions = $hasanyactions || $capabilitymanager->can_manage_forum($user);
+
+        $exporteddiscussion = array_merge($exporteddiscussion, [
+            'notifications' => $this->get_notifications($user),
+            'html' => [
+                'hasanyactions' => $hasanyactions,
+                'posts' => $this->postsrenderer->render($user, [$this->forum], [$this->discussion], $posts),
+                'modeselectorform' => $this->get_display_mode_selector_html($displaymode, $user),
+                'subscribe' => null,
+                'movediscussion' => null,
+                'pindiscussion' => null,
+                'neighbourlinks' => $this->get_neighbour_links_html(),
+                'exportdiscussion' => !empty($CFG->enableportfolios) ? $this->get_export_discussion_html($user) : null
+            ],
+            'settingsselector' => true,
+        ]);
+
+        $capabilities = (array) $exporteddiscussion['capabilities'];
+
+        if ($capabilities['move']) {
+            $exporteddiscussion['html']['movediscussion'] = $this->get_move_discussion_html();
+        }
+
+        if (!empty($user->id)) {
+            $loggedinuser = $entityfactory->get_author_from_stdClass($user);
+            $exporteddiscussion['loggedinuser'] = [
+                'firstname' => $loggedinuser->get_first_name(),
+                'fullname' => $loggedinuser->get_full_name(),
+                'profileimageurl' => ($urlfactory->get_author_profile_image_url($loggedinuser, null))->out(false)
+            ];
+        }
+
+        $exporteddiscussion['throttlingwarningmsg'] = '';
+        $cmrecord = $this->forum->get_course_module_record();
+        if (($warningobj = forum_check_throttling($this->forumrecord, $cmrecord)) && $warningobj->canpost) {
+            $throttlewarnnotification = (new notification(
+                    get_string($warningobj->errorcode, $warningobj->module, $warningobj->additional)
+            ))->set_show_closebutton();
+            $exporteddiscussion['throttlingwarningmsg'] = $throttlewarnnotification->get_message();
+        }
+
+        if ($this->displaymode === FORUM_MODE_NESTED_V2) {
+            $template = 'mod_forum/forum_discussion_nested_v2';
+        } else {
+            $template = 'mod_forum/forum_discussion';
+        }
+
+        return $this->renderer->render_from_template($template, $exporteddiscussion);
+    }
+
+    /**
+     * Get the groups details for all groups available to the forum.
+     *
+     * @return  stdClass[]
+     */
+    private function get_groups_available_in_forum(): array {
+        $course = $this->forum->get_course_record();
+        $coursemodule = $this->forum->get_course_module_record();
+
+        return groups_get_all_groups($course->id, 0, $coursemodule->groupingid);
+    }
+
+    /**
+     * Get the exported discussion.
+     *
+     * @param stdClass $user The user viewing the discussion
+     * @return array
+     */
+    private function get_exported_discussion(stdClass $user): array {
+        $discussionexporter = $this->exporterfactory->get_discussion_exporter(
+            $user,
+            $this->forum,
+            $this->discussion,
+            $this->get_groups_available_in_forum()
+        );
+
+        return (array) $discussionexporter->export($this->renderer);
+    }
+
+    /**
+     * Get the HTML for the display mode selector.
+     *
+     * @param int $displaymode The current display mode
+     * @param stdClass $user The current user
+     * @return string
+     */
+    private function get_display_mode_selector_html(int $displaymode, stdClass $user): string {
+        $baseurl = $this->baseurl;
+        $select = new single_select(
+            $baseurl,
+            'mode',
+            forum_get_layout_modes(get_user_preferences('forum_useexperimentalui', false, $user)),
+            $displaymode,
+            null,
+            'mode'
+        );
+        $select->set_label(get_string('displaymode', 'forum'), ['class' => 'accesshide']);
+
+        return $this->renderer->render($select);
+    }
+
+    /**
+     * Get the HTML to render the move discussion selector and button.
+     *
+     * @return string
+     */
+    private function get_move_discussion_html(): ?string {
+        global $DB;
+
+        $forum = $this->forum;
+        $discussion = $this->discussion;
+        $courseid = $forum->get_course_id();
+
+        // Popup menu to move discussions to other forums. The discussion in a
+        // single discussion forum can't be moved.
+        $modinfo = get_fast_modinfo($courseid);
+        if (isset($modinfo->instances['forum'])) {
+            $forummenu = [];
+            // Check forum types and eliminate simple discussions.
+            $forumcheck = $DB->get_records('forum', ['course' => $courseid], '', 'id, type');
+            foreach ($modinfo->instances['forum'] as $forumcm) {
+                if (!$forumcm->uservisible || !has_capability('mod/forum:startdiscussion',
+                    context_module::instance($forumcm->id))) {
+                    continue;
+                }
+                $section = $forumcm->sectionnum;
+                $sectionname = get_section_name($courseid, $section);
+                if (empty($forummenu[$section])) {
+                    $forummenu[$section] = [$sectionname => []];
+                }
+                $forumidcompare = $forumcm->instance != $forum->get_id();
+                $forumtypecheck = $forumcheck[$forumcm->instance]->type !== 'single';
+
+                if ($forumidcompare and $forumtypecheck) {
+                    $url = "/mod/forum/discuss.php?d={$discussion->get_id()}&move=$forumcm->instance&sesskey=".sesskey();
+                    $forummenu[$section][$sectionname][$url] = format_string($forumcm->name);
+                }
+            }
+            if (!empty($forummenu)) {
+                $html = '<div class="movediscussionoption">';
+
+                $movebutton = get_string('move');
+                if ($this->displaymode === FORUM_MODE_NESTED_V2) {
+                    // Move discussion selector will be rendered on the settings drawer. We won't output the button in this mode.
+                    $movebutton = null;
+                }
+                $select = new url_select($forummenu, '',
+                        ['/mod/forum/discuss.php?d=' . $discussion->get_id() => get_string("movethisdiscussionto", "forum")],
+                        'forummenu', $movebutton);
+                $select->set_label(get_string('movethisdiscussionlabel', 'mod_forum'), [
+                    'class' => 'sr-only',
+                ]);
+                $html .= $this->renderer->render($select);
+                $html .= "</div>";
+                return $html;
+            }
+        }
+
+        return null;
+    }
+
+    /**
+     * Get the HTML to render the export discussion button.
+     *
+     * @param   stdClass $user The user viewing the discussion
+     * @return  string|null
+     */
+    private function get_export_discussion_html(stdClass $user): ?string {
+        global $CFG;
+
+        if (!$this->capabilitymanager->can_export_discussions($user)) {
+            return null;
+        }
+
+        $button = new \portfolio_add_button();
+        $button->set_callback_options('forum_portfolio_caller', ['discussionid' => $this->discussion->get_id()], 'mod_forum');
+        $button = $button->to_html(PORTFOLIO_ADD_FULL_FORM, get_string('exportdiscussion', 'mod_forum'));
+        return $button ?: null;
+    }
+
+    /**
+     * Get a list of notification HTML to render in the page.
+     *
+     * @param stdClass $user The user viewing the discussion
+     * @return string[]
+     */
+    private function get_notifications($user): array {
+        $notifications = $this->notifications;
+        $discussion = $this->discussion;
+        $forum = $this->forum;
+
+        if ($forum->is_cutoff_date_reached()) {
+            $notifications[] = (new notification(
+                    get_string('cutoffdatereached', 'forum'),
+                    notification::NOTIFY_INFO
+            ))->set_show_closebutton();
+        } else if ($forum->get_type() != 'single') {
+            // Due date is already shown at the top of the page for single simple discussion forums.
+            if ($forum->is_due_date_reached()) {
+                $notifications[] = (new notification(
+                    get_string('thisforumisdue', 'forum', userdate($forum->get_due_date())),
+                    notification::NOTIFY_INFO
+                ))->set_show_closebutton();
+            } else if ($forum->has_due_date()) {
+                $notifications[] = (new notification(
+                    get_string('thisforumhasduedate', 'forum', userdate($forum->get_due_date())),
+                    notification::NOTIFY_INFO
+                ))->set_show_closebutton();
+            }
+        }
+
+        if ($forum->is_discussion_locked($discussion)) {
+            $notifications[] = (new notification(
+                get_string('discussionlocked', 'forum'),
+                notification::NOTIFY_INFO
+            ))
+            ->set_extra_classes(['discussionlocked'])
+            ->set_show_closebutton();
+        }
+
+        if ($forum->get_type() == 'qanda') {
+            if ($this->capabilitymanager->must_post_before_viewing_discussion($user, $discussion)) {
+                $notifications[] = (new notification(
+                    get_string('qandanotify', 'forum')
+                ))->set_show_closebutton(true)->set_extra_classes(['mt-3']);
+            }
+        }
+
+        if ($forum->has_blocking_enabled()) {
+            $notifications[] = (new notification(
+                get_string('thisforumisthrottled', 'forum', [
+                    'blockafter' => $forum->get_block_after(),
+                    'blockperiod' => get_string('secondstotime' . $forum->get_block_period())
+                ]),
+                notification::NOTIFY_INFO
+            ))->set_show_closebutton();
+
+        }
+
+        return array_map(function($notification) {
+            return $notification->export_for_template($this->renderer);
+        }, $notifications);
+    }
+
+    /**
+     * Get HTML to display the neighbour links.
+     *
+     * @return string
+     */
+    private function get_neighbour_links_html(): string {
+        $forum = $this->forum;
+        $coursemodule = $forum->get_course_module_record();
+        $neighbours = forum_get_discussion_neighbours($coursemodule, $this->discussionrecord, $this->forumrecord);
+        return $this->renderer->neighbouring_discussion_navigation($neighbours['prev'], $neighbours['next']);
+    }
+}

mod/forum/classes/local/renderers/discussion_list.php

@@ -0,0 +1,425 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Discussion list renderer.
+ *
+ * @package    mod_forum
+ * @copyright  2019 Andrew Nicols <andrew@nicols.co.uk>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_forum\local\renderers;
+
+defined('MOODLE_INTERNAL') || die();
+
+use mod_forum\grades\forum_gradeitem;
+use mod_forum\local\entities\forum as forum_entity;
+use mod_forum\local\factories\legacy_data_mapper as legacy_data_mapper_factory;
+use mod_forum\local\factories\exporter as exporter_factory;
+use mod_forum\local\factories\vault as vault_factory;
+use mod_forum\local\factories\url as url_factory;
+use mod_forum\local\managers\capability as capability_manager;
+use mod_forum\local\vaults\discussion_list as discussion_list_vault;
+use renderer_base;
+use stdClass;
+use core\output\notification;
+use mod_forum\local\data_mappers\legacy\forum;
+use mod_forum\local\factories\builder as builder_factory;
+
+require_once($CFG->dirroot . '/mod/forum/lib.php');
+
+/**
+ * The discussion list renderer.
+ *
+ * @package    mod_forum
+ * @copyright  2019 Andrew Nicols <andrew@nicols.co.uk>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class discussion_list {
+    /** @var forum_entity The forum being rendered */
+    private $forum;
+
+    /** @var stdClass The DB record for the forum being rendered */
+    private $forumrecord;
+
+    /** @var renderer_base The renderer used to render the view */
+    private $renderer;
+
+    /** @var legacy_data_mapper_factory $legacydatamapperfactory Legacy data mapper factory */
+    private $legacydatamapperfactory;
+
+    /** @var exporter_factory $exporterfactory Exporter factory */
+    private $exporterfactory;
+
+    /** @var vault_factory $vaultfactory Vault factory */
+    private $vaultfactory;
+
+    /** @var capability_manager $capabilitymanager Capability manager */
+    private $capabilitymanager;
+
+    /** @var url_factory $urlfactory URL factory */
+    private $urlfactory;
+
+    /** @var array $notifications List of notification HTML */
+    private $notifications;
+
+    /** @var builder_factory $builderfactory Builder factory */
+    private $builderfactory;
+
+    /** @var callable $postprocessfortemplate Function to process exported posts before template rendering */
+    private $postprocessfortemplate;
+
+    /** @var string $template The template to use when displaying */
+    private $template;
+
+    /** @var gradeitem The gradeitem instance associated with this forum */
+    private $forumgradeitem;
+
+    /**
+     * Constructor for a new discussion list renderer.
+     *
+     * @param   forum_entity        $forum The forum entity to be rendered
+     * @param   renderer_base       $renderer The renderer used to render the view
+     * @param   legacy_data_mapper_factory $legacydatamapperfactory The factory used to fetch a legacy record
+     * @param   exporter_factory    $exporterfactory The factory used to fetch exporter instances
+     * @param   vault_factory       $vaultfactory The factory used to fetch the vault instances
+     * @param   builder_factory     $builderfactory The factory used to fetch the builder instances
+     * @param   capability_manager  $capabilitymanager The managed used to check capabilities on the forum
+     * @param   url_factory         $urlfactory The factory used to create URLs in the forum
+     * @param   string              $template
+     * @param   notification[]      $notifications A list of any notifications to be displayed within the page
+     * @param   callable|null       $postprocessfortemplate Callback function to process discussion lists for templates
+     */
+    public function __construct(
+        forum_entity $forum,
+        renderer_base $renderer,
+        legacy_data_mapper_factory $legacydatamapperfactory,
+        exporter_factory $exporterfactory,
+        vault_factory $vaultfactory,
+        builder_factory $builderfactory,
+        capability_manager $capabilitymanager,
+        url_factory $urlfactory,
+        forum_gradeitem $forumgradeitem,
+        string $template,
+        array $notifications = [],
+        callable $postprocessfortemplate = null
+    ) {
+        $this->forum = $forum;
+        $this->renderer = $renderer;
+        $this->legacydatamapperfactory = $legacydatamapperfactory;
+        $this->exporterfactory = $exporterfactory;
+        $this->vaultfactory = $vaultfactory;
+        $this->builderfactory = $builderfactory;
+        $this->capabilitymanager = $capabilitymanager;
+
+        $this->urlfactory = $urlfactory;
+        $this->notifications = $notifications;
+        $this->postprocessfortemplate = $postprocessfortemplate;
+        $this->template = $template;
+        $this->forumgradeitem = $forumgradeitem;
+
+        $forumdatamapper = $this->legacydatamapperfactory->get_forum_data_mapper();
+        $this->forumrecord = $forumdatamapper->to_legacy_object($forum);
+    }
+
+    /**
+     * Render for the specified user.
+     *
+     * @param   stdClass    $user The user to render for
+     * @param   cm_info     $cm The course module info for this discussion list
+     * @param   int         $groupid The group to render
+     * @param   int         $sortorder The sort order to use when selecting the discussions in the list
+     * @param   int         $pageno The zero-indexed page number to use
+     * @param   int         $pagesize The number of discussions to show on the page
+     * @param   int         $displaymode The discussion display mode
+     * @param   bool        $enablediscussioncreation To show the discussion button.
+     * @return  string      The rendered content for display
+     */
+    public function render(
+        stdClass $user,
+        \cm_info $cm,
+        ?int $groupid,
+        ?int $sortorder,
+        ?int $pageno,
+        ?int $pagesize,
+        int $displaymode = null,
+        bool $enablediscussioncreation = true
+    ): string {
+        global $PAGE;
+
+        $forum = $this->forum;
+        $course = $forum->get_course_record();
+
+        $forumexporter = $this->exporterfactory->get_forum_exporter(
+            $user,
+            $this->forum,
+            $groupid
+        );
+
+        $pagesize = $this->get_page_size($pagesize);
+        $pageno = $this->get_page_number($pageno);
+
+        // Count all forum discussion posts.
+        $alldiscussionscount = mod_forum_count_all_discussions($forum, $user, $groupid);
+
+        // Get all forum discussion summaries.
+        $discussions = mod_forum_get_discussion_summaries($forum, $user, $groupid, $sortorder, $pageno, $pagesize);
+
+        $capabilitymanager = $this->capabilitymanager;
+        $hasanyactions = false;
+        $hasanyactions = $hasanyactions || $capabilitymanager->can_favourite_discussion($user);
+        $hasanyactions = $hasanyactions || $capabilitymanager->can_pin_discussions($user);
+        $hasanyactions = $hasanyactions || $capabilitymanager->can_manage_forum($user);
+
+        $forumview = [
+            'forum' => (array) $forumexporter->export($this->renderer),
+            'contextid' => $forum->get_context()->id,
+            'cmid' => $cm->id,
+            'groupid' => $groupid,
+            'name' => format_string($forum->get_name()),
+            'courseid' => $course->id,
+            'coursename' => format_string($course->shortname),
+            'experimentaldisplaymode' => $displaymode == FORUM_MODE_NESTED_V2,
+            'gradingcomponent' => $this->forumgradeitem->get_grading_component_name(),
+            'gradingcomponentsubtype' => $this->forumgradeitem->get_grading_component_subtype(),
+            'sendstudentnotifications' => $forum->should_notify_students_default_when_grade_for_forum(),
+            'gradeonlyactiveusers' => $this->forumgradeitem->should_grade_only_active_users(),
+            'hasanyactions' => $hasanyactions,
+            'groupchangemenu' => groups_print_activity_menu(
+                $cm,
+                $this->urlfactory->get_forum_view_url_from_forum($forum),
+                true
+            ),
+            'hasmore' => ($alldiscussionscount > $pagesize),
+            'notifications' => $this->get_notifications($user, $groupid),
+            'settings' => [
+                'excludetext' => true,
+                'togglemoreicon' => true,
+                'excludesubscription' => true
+            ],
+            'totaldiscussioncount' => $alldiscussionscount,
+            'userid' => $user->id,
+            'visiblediscussioncount' => count($discussions),
+            'enablediscussioncreation' => $enablediscussioncreation,
+        ];
+
+        if ($forumview['forum']['capabilities']['create']) {
+            $forumview['newdiscussionhtml'] = $this->get_discussion_form($user, $cm, $groupid);
+        }
+
+        if (!$discussions) {
+            return $this->renderer->render_from_template($this->template, $forumview);
+        }
+
+        if ($this->postprocessfortemplate !== null) {
+            // We've got some post processing to do!
+            $exportedposts = ($this->postprocessfortemplate) ($discussions, $user, $forum);
+        }
+
+        $baseurl = new \moodle_url($PAGE->url, ['o' => $sortorder, 's' => $pagesize]);
+
+        $forumview = array_merge(
+            $forumview,
+            [
+                'pagination' => $this->renderer->render(new \paging_bar($alldiscussionscount, $pageno, $pagesize, $baseurl, 'p')),
+            ],
+            $exportedposts
+        );
+
+        $firstdiscussion = reset($discussions);
+        $forumview['firstgradeduserid'] = $firstdiscussion->get_latest_post_author()->get_id();
+
+        return $this->renderer->render_from_template($this->template, $forumview);
+    }
+
+    /**
+     * Add new discussion button to the action bar for tertiary nav.
+     *
+     * @param stdClass $user The user object.
+     * @param int|null $groupid The group id.
+     * @return string rendered HTML string
+     */
+    public function render_new_discussion(stdClass $user, ?int $groupid): string {
+        $forumexporter = $this->exporterfactory->get_forum_exporter(
+            $user,
+            $this->forum,
+            $groupid
+        );
+
+        $forumview = [
+            'forum' => (array) $forumexporter->export($this->renderer),
+        ];
+
+        return $this->renderer->render_from_template('mod_forum/forum_new_discussion_actionbar', $forumview);
+    }
+
+    /**
+     * Get the mod_forum_post_form. This is the default boiler plate from mod_forum/post_form.php with the inpage flag caveat
+     *
+     * @param stdClass $user The user the form is being generated for
+     * @param \cm_info $cm
+     * @param int $groupid The groupid if any
+     *
+     * @return string The rendered html
+     */
+    private function get_discussion_form(stdClass $user, \cm_info $cm, ?int $groupid) {
+        $forum = $this->forum;
+        $forumrecord = $this->legacydatamapperfactory->get_forum_data_mapper()->to_legacy_object($forum);
+        $modcontext = \context_module::instance($cm->id);
+        $coursecontext = \context_course::instance($forum->get_course_id());
+        $post = (object) [
+            'course' => $forum->get_course_id(),
+            'forum' => $forum->get_id(),
+            'discussion' => 0,           // Ie discussion # not defined yet.
+            'parent' => 0,
+            'subject' => '',
+            'userid' => $user->id,
+            'message' => '',
+            'messageformat' => editors_get_preferred_format(),
+            'messagetrust' => 0,
+            'groupid' => $groupid,
+        ];
+        $thresholdwarning = forum_check_throttling($forumrecord, $cm);
+
+        $formparams = array(
+            'course' => $forum->get_course_record(),
+            'cm' => $cm,
+            'coursecontext' => $coursecontext,
+            'modcontext' => $modcontext,
+            'forum' => $forumrecord,
+            'post' => $post,
+            'subscribe' => \mod_forum\subscriptions::is_subscribed($user->id, $forumrecord,
+                null, $cm),
+            'thresholdwarning' => $thresholdwarning,
+            'inpagereply' => true,
+            'edit' => 0
+        );
+        $posturl = new \moodle_url('/mod/forum/post.php');
+        $mformpost = new \mod_forum_post_form($posturl, $formparams, 'post', '', array('id' => 'mformforum'));
+        $discussionsubscribe = \mod_forum\subscriptions::get_user_default_subscription($forumrecord, $coursecontext, $cm, null);
+
+        $params = array('reply' => 0, 'forum' => $forumrecord->id, 'edit' => 0) +
+            (isset($post->groupid) ? array('groupid' => $post->groupid) : array()) +
+            array(
+                'userid' => $post->userid,
+                'parent' => $post->parent,
+                'discussion' => $post->discussion,
+                'course' => $forum->get_course_id(),
+                'discussionsubscribe' => $discussionsubscribe
+            );
+        $mformpost->set_data($params);
+
+        return $mformpost->render();
+    }
+
+    /**
+     * Fetch the page size to use when displaying the page.
+     *
+     * @param   int         $pagesize The number of discussions to show on the page
+     * @return  int         The normalised page size
+     */
+    private function get_page_size(?int $pagesize): int {
+        if (null === $pagesize || $pagesize <= 0) {
+            $pagesize = discussion_list_vault::PAGESIZE_DEFAULT;
+        }
+
+        return $pagesize;
+    }
+
+    /**
+     * Fetch the current page number (zero-indexed).
+     *
+     * @param   int         $pageno The zero-indexed page number to use
+     * @return  int         The normalised page number
+     */
+    private function get_page_number(?int $pageno): int {
+        if (null === $pageno || $pageno < 0) {
+            $pageno = 0;
+        }
+
+        return $pageno;
+    }
+
+    /**
+     * Get the list of notification for display.
+     *
+     * @param stdClass $user The viewing user
+     * @param int|null $groupid The forum's group id
+     * @return      array
+     */
+    private function get_notifications(stdClass $user, ?int $groupid): array {
+        $notifications = $this->notifications;
+        $forum = $this->forum;
+        $capabilitymanager = $this->capabilitymanager;
+
+        if ($forum->is_cutoff_date_reached()) {
+            $notifications[] = (new notification(
+                    get_string('cutoffdatereached', 'forum'),
+                    notification::NOTIFY_INFO
+            ))->set_show_closebutton();
+        }
+
+        if ($forum->has_blocking_enabled()) {
+            $notifications[] = (new notification(
+                get_string('thisforumisthrottled', 'forum', [
+                    'blockafter' => $forum->get_block_after(),
+                    'blockperiod' => get_string('secondstotime' . $forum->get_block_period())
+                ]),
+                notification::NOTIFY_INFO
+            ))->set_show_closebutton();
+        }
+
+        if ($forum->is_in_group_mode() && !$capabilitymanager->can_access_all_groups($user)) {
+            if ($groupid === null) {
+                if (!$capabilitymanager->can_post_to_my_groups($user)) {
+                    $notifications[] = (new notification(
+                        get_string('cannotadddiscussiongroup', 'mod_forum'),
+                        \core\output\notification::NOTIFY_WARNING
+                    ))->set_show_closebutton();
+                } else {
+                    $notifications[] = (new notification(
+                        get_string('cannotadddiscussionall', 'mod_forum'),
+                        \core\output\notification::NOTIFY_WARNING
+                    ))->set_show_closebutton();
+                }
+            } else if (!$capabilitymanager->can_access_group($user, $groupid)) {
+                $notifications[] = (new notification(
+                    get_string('cannotadddiscussion', 'mod_forum'),
+                    \core\output\notification::NOTIFY_WARNING
+                ))->set_show_closebutton();
+            }
+        }
+
+        if ('qanda' === $forum->get_type() && !$capabilitymanager->can_manage_forum($user)) {
+            $notifications[] = (new notification(
+                get_string('qandanotify', 'forum'),
+                notification::NOTIFY_INFO
+            ))->set_show_closebutton()->set_extra_classes(['mt-3']);
+        }
+
+        if ('eachuser' === $forum->get_type()) {
+            $notifications[] = (new notification(
+                get_string('allowsdiscussions', 'forum'),
+                notification::NOTIFY_INFO)
+            )->set_show_closebutton();
+        }
+
+        return array_map(function($notification) {
+            return $notification->export_for_template($this->renderer);
+        }, $notifications);
+    }
+}

mod/forum/classes/local/renderers/posts.php

@@ -0,0 +1,111 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Posts renderer.
+ *
+ * @package    mod_forum
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_forum\local\renderers;
+
+defined('MOODLE_INTERNAL') || die();
+
+use mod_forum\local\builders\exported_posts as exported_posts_builder;
+use renderer_base;
+use stdClass;
+
+/**
+ * Posts renderer class.
+ *
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class posts {
+    /** @var renderer_base $renderer Renderer base */
+    private $renderer;
+    /** @var exported_posts_builder $exportedpostsbuilder Builder for building exported posts */
+    private $exportedpostsbuilder;
+    /** @var string $template The template to render */
+    private $template;
+    /** @var callable $postprocessfortemplate Function to process exported posts before template rendering */
+    private $postprocessfortemplate;
+
+    /**
+     * Constructor.
+     *
+     * @param renderer_base $renderer Renderer base
+     * @param exported_posts_builder $exportedpostsbuilder Builder for building exported posts
+     * @param string $template The template to render
+     * @param callable $postprocessfortemplate Function to process exported posts before template rendering
+     */
+    public function __construct(
+        renderer_base $renderer,
+        exported_posts_builder $exportedpostsbuilder,
+        string $template,
+        callable $postprocessfortemplate = null
+    ) {
+        $this->renderer = $renderer;
+        $this->exportedpostsbuilder = $exportedpostsbuilder;
+        $this->template = $template;
+        $this->postprocessfortemplate = $postprocessfortemplate;
+    }
+
+    /**
+     * Render the given posts for the forums and discussions.
+     *
+     * @param stdClass $user The user viewing the posts
+     * @param forum_entity[] $forums A list of all forums for these posts
+     * @param discussion_entity[] $discussions A list of all discussions for these posts
+     * @param post_entity[] $posts The posts to render
+     * @return string
+     */
+    public function render(
+        stdClass $user,
+        array $forums,
+        array $discussions,
+        array $posts
+    ): string {
+        // Format the forums and discussion to make them more easily accessed later.
+        $forums = array_reduce($forums, function($carry, $forum) {
+            $carry[$forum->get_id()] = $forum;
+            return $carry;
+        }, []);
+        $discussions = array_reduce($discussions, function($carry, $discussion) {
+            $carry[$discussion->get_id()] = $discussion;
+            return $carry;
+        }, []);
+
+        $exportedposts = $this->exportedpostsbuilder->build(
+            $user,
+            $forums,
+            $discussions,
+            $posts
+        );
+
+        if ($this->postprocessfortemplate !== null) {
+            // We've got some post processing to do!
+            $exportedposts = ($this->postprocessfortemplate)($exportedposts, $forums, $discussions, $user);
+        }
+
+        return $this->renderer->render_from_template(
+            $this->template,
+            ['posts' => array_values($exportedposts)]
+        );
+    }
+}

mod/forum/classes/local/vaults/author.php

@@ -0,0 +1,120 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Author vault class.
+ *
+ * @package    mod_forum
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_forum\local\vaults;
+
+defined('MOODLE_INTERNAL') || die();
+
+/**
+ * Author vault class.
+ *
+ * This should be the only place that accessed the database.
+ *
+ * This uses the repository pattern. See:
+ * https://designpatternsphp.readthedocs.io/en/latest/More/Repository/README.html
+ *
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class author extends db_table_vault {
+    /** The table for this vault */
+    private const TABLE = 'user';
+
+    /**
+     * Get the table alias.
+     *
+     * @return string
+     */
+    protected function get_table_alias(): string {
+        return 'a';
+    }
+
+    /**
+     * Build the SQL to be used in get_records_sql.
+     *
+     * @param string|null $wheresql Where conditions for the SQL
+     * @param string|null $sortsql Order by conditions for the SQL
+     * @param int|null $userid The user ID
+     * @return string
+     */
+    protected function generate_get_records_sql(string $wheresql = null, string $sortsql = null, ?int $userid = null): string {
+        $selectsql = 'SELECT * FROM {' . self::TABLE . '} ' . $this->get_table_alias();
+        $selectsql .= $wheresql ? ' WHERE ' . $wheresql : '';
+        $selectsql .= $sortsql ? ' ORDER BY ' . $sortsql : '';
+
+        return $selectsql;
+    }
+
+    /**
+     * Convert the DB records into author entities.
+     *
+     * @param array $results The DB records
+     * @return author_entity[]
+     */
+    protected function from_db_records(array $results) {
+        $entityfactory = $this->get_entity_factory();
+
+        return array_map(function(array $result) use ($entityfactory) {
+            [
+                'record' => $record,
+            ] = $result;
+            return $entityfactory->get_author_from_stdclass($record);
+        }, $results);
+    }
+
+    /**
+     * Get the authors for the given posts.
+     *
+     * Returns a distinct list of authors indexed by author id.
+     *
+     * @param post_entity[] $posts The list of posts
+     * @return author_entity[]
+     */
+    public function get_authors_for_posts(array $posts): array {
+        $authorids = array_reduce($posts, function($carry, $post) {
+            $carry[$post->get_author_id()] = true;
+            return $carry;
+        }, []);
+        $authorids = array_keys($authorids);
+        return $this->get_from_ids($authorids);
+    }
+
+    /**
+     * Get the context ids for a set of author ids. The results are indexed
+     * by the author id.
+     *
+     * @param int[] $authorids The list of author ids to fetch.
+     * @return int[] Results indexed by author id.
+     */
+    public function get_context_ids_for_author_ids(array $authorids): array {
+        $db = $this->get_db();
+        [$insql, $params] = $db->get_in_or_equal($authorids);
+        $sql = "SELECT instanceid, id FROM {context} WHERE contextlevel = ? AND instanceid {$insql}";
+        $records = $db->get_records_sql($sql, array_merge([CONTEXT_USER], $params));
+        return array_reduce($authorids, function($carry, $id) use ($records) {
+            $carry[$id] = isset($records[$id]) ? (int) $records[$id]->id : null;
+            return $carry;
+        }, []);
+    }
+}

mod/forum/classes/local/vaults/db_table_vault.php

@@ -0,0 +1,189 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Abstract class for loading records from the DB.
+ *
+ * @package    mod_forum
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_forum\local\vaults;
+
+defined('MOODLE_INTERNAL') || die();
+
+use mod_forum\local\factories\entity as entity_factory;
+use moodle_database;
+
+/**
+ * Abstract class for loading records from the DB.
+ *
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+abstract class db_table_vault {
+    /** @var moodle_database $db A moodle database */
+    private $db;
+    /** @var entity_factory $entityfactory Entity factory */
+    private $entityfactory;
+    /** @var object $legacyfactory Entity->legacy factory */
+    private $legacyfactory;
+
+    /**
+     * Constructor.
+     *
+     * @param moodle_database $db A moodle database
+     * @param entity_factory $entityfactory Entity factory
+     * @param object $legacyfactory Legacy factory
+     */
+    public function __construct(
+        moodle_database $db,
+        entity_factory $entityfactory,
+        $legacyfactory
+    ) {
+        $this->db = $db;
+        $this->entityfactory = $entityfactory;
+        $this->legacyfactory = $legacyfactory;
+    }
+
+    /**
+     * Get the table alias.
+     *
+     * @return string
+     */
+    abstract protected function get_table_alias(): string;
+
+    /**
+     * Build the SQL to be used in get_records_sql.
+     *
+     * @param string|null $wheresql Where conditions for the SQL
+     * @param string|null $sortsql Order by conditions for the SQL
+     * @param object|null $user The user object
+     * @return string
+     */
+    abstract protected function generate_get_records_sql(string $wheresql = null, string $sortsql = null,
+        ?int $userid = null): string;
+
+    /**
+     * Convert the DB records into entities. The list of records will have been
+     * passed through any preprocessors that may be defined before being given to
+     * this function.
+     *
+     * Each result will from the list will be an associative array where the key
+     * is set to the identifier given to the preprocessor and the result is the value
+     * generated by the preprocessor.
+     *
+     * All results will have a 'record' key who's value is the original DB record.
+     *
+     * @param array $results The DB records
+     */
+    abstract protected function from_db_records(array $results);
+
+    /**
+     * Get the list of preprocessors to run on the DB record results. The preprocessors
+     * should be defined using an associative array. The key used to identify the
+     * preprocessor in this list will be used to identify the value of that preprocessor
+     * in the list of results when passed to the from_db_records function.
+     *
+     * @return array
+     */
+    protected function get_preprocessors(): array {
+        return [];
+    }
+
+    /**
+     * Get the moodle database.
+     *
+     * @return moodle_database
+     */
+    protected function get_db(): moodle_database {
+        return $this->db;
+    }
+
+    /**
+     * Get the entity factory.
+     *
+     * @return entity_factory
+     */
+    protected function get_entity_factory(): entity_factory {
+        return $this->entityfactory;
+    }
+
+    /**
+     * Get the legacy factory
+     *
+     * @return object
+     */
+    protected function get_legacy_factory() {
+        return $this->legacyfactory;
+    }
+
+    /**
+     * Execute the defined preprocessors on the DB record results and then convert
+     * them into entities.
+     *
+     * @param stdClass[] $records List of DB results
+     * @return array
+     */
+    protected function transform_db_records_to_entities(array $records) {
+        $preprocessors = $this->get_preprocessors();
+        $result = array_map(function($record) {
+            return ['record' => $record];
+        }, $records);
+
+        $result = array_reduce(array_keys($preprocessors), function($carry, $preprocessor) use ($records, $preprocessors) {
+            $step = $preprocessors[$preprocessor];
+            $dependencies = $step->execute($records);
+
+            foreach ($dependencies as $index => $dependency) {
+                // Add the new dependency to the list.
+                $carry[$index] = array_merge($carry[$index], [$preprocessor => $dependency]);
+            }
+
+            return $carry;
+        }, $result);
+
+        return $this->from_db_records($result);
+    }
+
+    /**
+     * Get the entity for the given id.
+     *
+     * @param int $id Identifier for the entity
+     * @return object|null
+     */
+    public function get_from_id(int $id) {
+        $records = $this->get_from_ids([$id]);
+        return count($records) ? array_shift($records) : null;
+    }
+
+    /**
+     * Get the list of entities for the given ids.
+     *
+     * @param int[] $ids Identifiers
+     * @return array
+     */
+    public function get_from_ids(array $ids) {
+        $alias = $this->get_table_alias();
+        list($insql, $params) = $this->get_db()->get_in_or_equal($ids);
+        $wheresql = $alias . '.id ' . $insql;
+        $sql = $this->generate_get_records_sql($wheresql);
+        $records = $this->get_db()->get_records_sql($sql, $params);
+
+        return $this->transform_db_records_to_entities($records);
+    }
+}

mod/forum/classes/local/vaults/discussion.php

@@ -0,0 +1,175 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Discussion vault class.
+ *
+ * @package    mod_forum
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_forum\local\vaults;
+
+defined('MOODLE_INTERNAL') || die();
+
+use mod_forum\local\container;
+use mod_forum\local\entities\forum as forum_entity;
+use mod_forum\local\entities\discussion as discussion_entity;
+
+/**
+ * Discussion vault class.
+ *
+ * This should be the only place that accessed the database.
+ *
+ * This uses the repository pattern. See:
+ * https://designpatternsphp.readthedocs.io/en/latest/More/Repository/README.html
+ *
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class discussion extends db_table_vault {
+    /** The table for this vault */
+    private const TABLE = 'forum_discussions';
+
+    /**
+     * Get the table alias.
+     *
+     * @return string
+     */
+    protected function get_table_alias(): string {
+        return 'd';
+    }
+
+    /**
+     * Build the SQL to be used in get_records_sql.
+     *
+     * @param string|null $wheresql Where conditions for the SQL
+     * @param string|null $sortsql Order by conditions for the SQL
+     * @param int|null $userid The user ID
+     * @return string
+     */
+    protected function generate_get_records_sql(string $wheresql = null, string $sortsql = null, ?int $userid = null): string {
+        $selectsql = 'SELECT * FROM {' . self::TABLE . '} ' . $this->get_table_alias();
+        $selectsql .= $wheresql ? ' WHERE ' . $wheresql : '';
+        $selectsql .= $sortsql ? ' ORDER BY ' . $sortsql : '';
+
+        return $selectsql;
+    }
+
+    /**
+     * Convert the DB records into discussion entities.
+     *
+     * @param array $results The DB records
+     * @return discussion_entity[]
+     */
+    protected function from_db_records(array $results) {
+        $entityfactory = $this->get_entity_factory();
+
+        return array_map(function(array $result) use ($entityfactory) {
+            [
+                'record' => $record,
+            ] = $result;
+            return $entityfactory->get_discussion_from_stdclass($record);
+        }, $results);
+    }
+
+    /**
+     * Get all discussions in the specified forum.
+     *
+     * @param   forum_entity $forum
+     * @return  array
+     */
+    public function get_all_discussions_in_forum(forum_entity $forum, string $sort = null): ?array {
+        global $USER;
+        $options = ['forum' => $forum->get_id()];
+
+        $managerfactory = container::get_manager_factory();
+        $capabilitymanager = $managerfactory->get_capability_manager($forum);
+
+        $select = "forum = :forum";
+
+        if ($forum->is_in_group_mode() && !$capabilitymanager->can_access_all_groups($USER)) {
+            $allowedgroups = groups_get_activity_allowed_groups($forum->get_course_module_record());
+            $allowedgroups = implode(",", array_keys($allowedgroups));
+            if (!$allowedgroups) {
+                return [];
+            }
+            $select .= " AND groupid IN ($allowedgroups)";
+        }
+        $records = $this->get_db()->get_records_select(self::TABLE, $select, $options, $sort ?? '');
+
+        return $this->transform_db_records_to_entities($records);
+    }
+
+    /**
+     * Get the first discussion in the specified forum.
+     *
+     * @param   forum_entity $forum
+     * @return  discussion_entity|null
+     */
+    public function get_first_discussion_in_forum(forum_entity $forum): ?discussion_entity {
+        $records = $this->get_db()->get_records(self::TABLE, [
+            'forum' => $forum->get_id(),
+        ], 'timemodified ASC', '*', 0, 1);
+
+        $records = $this->transform_db_records_to_entities($records);
+        return count($records) ? array_shift($records) : null;
+    }
+
+    /**
+     * Get the last discussion in the specified forum.
+     *
+     * @param   forum_entity $forum
+     * @return  discussion_entity|null
+     */
+    public function get_last_discussion_in_forum(forum_entity $forum): ?discussion_entity {
+        $records = $this->get_db()->get_records(self::TABLE, [
+            'forum' => $forum->get_id(),
+        ], 'timemodified DESC', '*', 0, 1);
+
+        $records = $this->transform_db_records_to_entities($records);
+        return count($records) ? array_shift($records) : null;
+    }
+
+    /**
+     * Get the count of the discussions in the specified forum.
+     *
+     * @param   forum_entity $forum
+     * @return  int
+     */
+    public function get_count_discussions_in_forum(forum_entity $forum): ?int {
+        return $this->get_db()->count_records(self::TABLE, [
+            'forum' => $forum->get_id()]);
+    }
+
+    /**
+     * Update the discussion
+     *
+     * @param discussion_entity $discussion
+     * @return discussion_entity|null
+     */
+    public function update_discussion(discussion_entity $discussion): ?discussion_entity {
+        $discussionrecord = $this->get_legacy_factory()->to_legacy_object($discussion);
+        if ($this->get_db()->update_record('forum_discussions', $discussionrecord)) {
+            $records = $this->transform_db_records_to_entities([$discussionrecord]);
+
+            return count($records) ? array_shift($records) : null;
+        }
+
+        return null;
+    }
+}

mod/forum/classes/local/vaults/discussion_list.php

@@ -0,0 +1,564 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Vault class for a discussion list.
+ *
+ * @package    mod_forum
+ * @copyright  2019 Andrew Nicols <andrew@nicols.co.uk>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_forum\local\vaults;
+
+defined('MOODLE_INTERNAL') || die();
+
+use core_group\output\group_details;
+use mod_forum\local\vaults\preprocessors\extract_record as extract_record_preprocessor;
+use mod_forum\local\vaults\preprocessors\extract_user as extract_user_preprocessor;
+use mod_forum\local\renderers\discussion_list as discussion_list_renderer;
+use core\dml\table as dml_table;
+use stdClass;
+
+/**
+ * Discussion list vault.
+ *
+ * This should be the only place that accessed the database.
+ *
+ * This uses the repository pattern. See:
+ * https://designpatternsphp.readthedocs.io/en/latest/More/Repository/README.html
+ *
+ * @package    mod_forum
+ * @copyright  2019 Andrew Nicols <andrew@nicols.co.uk>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class discussion_list extends db_table_vault {
+    /** The table for this vault */
+    private const TABLE = 'forum_discussions';
+    /** Alias for first author id */
+    private const FIRST_AUTHOR_ID_ALIAS = 'fauserpictureid';
+    /** Alias for author fields */
+    private const FIRST_AUTHOR_ALIAS = 'fauserrecord';
+    /** Alias for last author id */
+    private const LATEST_AUTHOR_ID_ALIAS = 'lauserpictureid';
+    /** Alias for last author fields */
+    private const LATEST_AUTHOR_ALIAS = 'lauserrecord';
+    /** Default limit */
+    public const PAGESIZE_DEFAULT = 100;
+
+    /** Sort by newest first */
+    public const SORTORDER_LASTPOST_DESC = 1;
+    /** Sort by oldest first */
+    public const SORTORDER_LASTPOST_ASC = 2;
+    /** Sort by created desc */
+    public const SORTORDER_CREATED_DESC = 3;
+    /** Sort by created asc */
+    public const SORTORDER_CREATED_ASC = 4;
+    /** Sort by number of replies desc */
+    public const SORTORDER_REPLIES_DESC = 5;
+    /** Sort by number of replies desc */
+    public const SORTORDER_REPLIES_ASC = 6;
+    /** Sort by discussion name desc */
+    public const SORTORDER_DISCUSSION_DESC = 7;
+    /** Sort by discussion name asc */
+    public const SORTORDER_DISCUSSION_ASC = 8;
+    /** Sort by discussion starter's name desc */
+    public const SORTORDER_STARTER_DESC = 9;
+    /** Sort by discussion starter's name asc */
+    public const SORTORDER_STARTER_ASC = 10;
+    /** Sort by group name desc */
+    public const SORTORDER_GROUP_DESC = 11;
+    /** Sort by group name asc */
+    public const SORTORDER_GROUP_ASC = 12;
+
+    /**
+     * Get the table alias.
+     *
+     * @return string
+     */
+    protected function get_table_alias(): string {
+        return 'd';
+    }
+
+    /**
+     * Get the favourite table alias
+     *
+     * @return string
+     */
+    protected function get_favourite_alias(): string {
+        return 'favalias';
+    }
+
+    /**
+     * Build the SQL to be used in get_records_sql.
+     *
+     * @param string|null $wheresql Where conditions for the SQL
+     * @param string|null $sortsql Order by conditions for the SQL
+     * @param int|null $userid The ID of the user we are performing this query for
+     *
+     * @return string
+     */
+    protected function generate_get_records_sql(string $wheresql = null, ?string $sortsql = null, ?int $userid = null): string {
+        $alias = $this->get_table_alias();
+
+        $includefavourites = $userid ? true : false;
+
+        $favsql = '';
+        if ($includefavourites) {
+            list($favsql, $favparams) = $this->get_favourite_sql($userid);
+            foreach ($favparams as $key => $param) {
+                $favsql = str_replace(":$key", "'$param'", $favsql);
+            }
+        }
+
+        // Fetch:
+        // - Discussion
+        // - First post
+        // - Author
+        // - Most recent editor.
+        $thistable = new dml_table(self::TABLE, $alias, $alias);
+        $posttable = new dml_table('forum_posts', 'fp', 'p_');
+        $userfieldsapi = \core_user\fields::for_userpic()->including('deleted');
+        $firstauthorfields = $userfieldsapi->get_sql('fa', false,
+                self::FIRST_AUTHOR_ALIAS, self::FIRST_AUTHOR_ID_ALIAS, false)->selects;
+        $latestuserfields = $userfieldsapi->get_sql('la', false,
+                self::LATEST_AUTHOR_ALIAS, self::LATEST_AUTHOR_ID_ALIAS, false)->selects;
+
+        $fields = implode(', ', [
+            $thistable->get_field_select(),
+            $posttable->get_field_select(),
+            $firstauthorfields,
+            $latestuserfields,
+        ]);
+
+        $sortkeys = [
+            $this->get_sort_order(self::SORTORDER_REPLIES_DESC, $includefavourites),
+            $this->get_sort_order(self::SORTORDER_REPLIES_ASC, $includefavourites)
+        ];
+        $issortbyreplies = in_array($sortsql, $sortkeys);
+
+        $tables = $thistable->get_from_sql();
+        $tables .= ' JOIN ' . $posttable->get_from_sql() . ' ON fp.id = ' . $alias . '.firstpost';
+        $tables .= ' JOIN {user} fa ON fa.id = fp.userid';
+        $tables .= ' JOIN {user} la ON la.id = ' . $alias . '.usermodified';
+        $tables .= $favsql;
+
+        if ($issortbyreplies) {
+            // Join the discussion replies.
+            $tables .= ' JOIN (
+                            SELECT rd.id, COUNT(rp.id) as replycount
+                            FROM {forum_discussions} rd
+                            LEFT JOIN {forum_posts} rp
+                                ON rp.discussion = rd.id AND rp.id != rd.firstpost
+                            GROUP BY rd.id
+                         ) r ON d.id = r.id';
+        }
+
+        $groupsortorders = [
+            $this->get_sort_order(self::SORTORDER_GROUP_DESC, $includefavourites),
+            $this->get_sort_order(self::SORTORDER_GROUP_ASC, $includefavourites)
+        ];
+        $sortbygroup = in_array($sortsql, $groupsortorders);
+        if ($sortbygroup) {
+            $groupstable = new dml_table('groups', 'g', 'g');
+            $fields .= ', ' . $groupstable->get_field_select();
+            // Join groups.
+            $tables .= 'LEFT JOIN {groups} g ON g.id = d.groupid';
+        }
+
+        $selectsql = 'SELECT ' . $fields . ' FROM ' . $tables;
+        $selectsql .= $wheresql ? ' WHERE ' . $wheresql : '';
+        $selectsql .= $sortsql ? ' ORDER BY ' . $sortsql : '';
+
+        return $selectsql;
+    }
+
+    /**
+     * Build the SQL to be used in count_records_sql.
+     *
+     * @param string|null $wheresql Where conditions for the SQL
+     * @return string
+     */
+    protected function generate_count_records_sql(string $wheresql = null): string {
+        $alias = $this->get_table_alias();
+        $db = $this->get_db();
+
+        $selectsql = "SELECT COUNT(1) FROM {" . self::TABLE . "} {$alias}";
+        $selectsql .= $wheresql ? ' WHERE ' . $wheresql : '';
+
+        return $selectsql;
+    }
+
+    /**
+     * Get a list of preprocessors to execute on the DB results before being converted
+     * into entities.
+     *
+     * @return array
+     */
+    protected function get_preprocessors(): array {
+        return array_merge(
+            parent::get_preprocessors(),
+            [
+                'discussion' => new extract_record_preprocessor(self::TABLE, $this->get_table_alias()),
+                'firstpost' => new extract_record_preprocessor('forum_posts', 'p_'),
+                'firstpostauthor' => new extract_user_preprocessor(self::FIRST_AUTHOR_ID_ALIAS, self::FIRST_AUTHOR_ALIAS),
+                'latestpostauthor' => new extract_user_preprocessor(self::LATEST_AUTHOR_ID_ALIAS, self::LATEST_AUTHOR_ALIAS),
+            ]
+        );
+    }
+
+    /**
+     * Convert the DB records into discussion list entities.
+     *
+     * @param array $results The DB records
+     * @return discussion_list[]
+     */
+    protected function from_db_records(array $results) {
+        $entityfactory = $this->get_entity_factory();
+
+        return array_map(function(array $result) use ($entityfactory) {
+            [
+                'discussion' => $discussion,
+                'firstpost' => $firstpost,
+                'firstpostauthor' => $firstpostauthor,
+                'latestpostauthor' => $latestpostauthor,
+            ] = $result;
+            return $entityfactory->get_discussion_summary_from_stdclass(
+                $discussion,
+                $firstpost,
+                $firstpostauthor,
+                $latestpostauthor
+            );
+        }, $results);
+    }
+
+    /**
+     * Get the field to sort by.
+     *
+     * @param int|null $sortmethod
+     * @return string
+     */
+    protected function get_keyfield(?int $sortmethod): string {
+        global $CFG;
+
+        switch ($sortmethod) {
+            case self::SORTORDER_CREATED_DESC:
+            case self::SORTORDER_CREATED_ASC:
+                return 'fp.created';
+            case self::SORTORDER_REPLIES_DESC:
+            case self::SORTORDER_REPLIES_ASC:
+                return 'replycount';
+            case self::SORTORDER_DISCUSSION_DESC:
+            case self::SORTORDER_DISCUSSION_ASC:
+                return 'dname';
+            case self::SORTORDER_STARTER_DESC:
+            case self::SORTORDER_STARTER_ASC:
+                // We'll sort by the first name field of the discussion starter's name.
+
+                // Let's get the full name display config first.
+                $nameformat = $CFG->fullnamedisplay;
+                if ($CFG->fullnamedisplay === 'language') {
+                    $nameformat = get_string('fullnamedisplay', '', (object)['firstname' => 'firstname', 'lastname' => 'lastname']);
+                }
+                // Fetch all the available user name fields.
+                $availablefields = order_in_string(\core_user\fields::get_name_fields(), $nameformat);
+                // We'll default to the first name if there's no available name field.
+                $returnfield = 'firstname';
+                if (!empty($availablefields)) {
+                    // Use the first name field.
+                    $returnfield = reset($availablefields);
+                }
+                return 'fauserrecord' . $returnfield;
+            case self::SORTORDER_GROUP_DESC:
+            case self::SORTORDER_GROUP_ASC:
+                return 'gname';
+            default:
+                global $CFG;
+                $alias = $this->get_table_alias();
+                $field = "{$alias}.timemodified";
+                if (!empty($CFG->forum_enabletimedposts)) {
+                    return "CASE WHEN {$field} < {$alias}.timestart THEN {$alias}.timestart ELSE {$field} END";
+                }
+                return $field;
+        }
+    }
+
+    /**
+     * Get the sort direction.
+     *
+     * @param int|null $sortmethod
+     * @return string
+     */
+    protected function get_sort_direction(?int $sortmethod): string {
+        switch ($sortmethod) {
+            case self::SORTORDER_LASTPOST_ASC:
+            case self::SORTORDER_CREATED_ASC:
+            case self::SORTORDER_REPLIES_ASC:
+            case self::SORTORDER_DISCUSSION_ASC:
+            case self::SORTORDER_STARTER_ASC:
+            case self::SORTORDER_GROUP_ASC:
+                return "ASC";
+            case self::SORTORDER_LASTPOST_DESC:
+            case self::SORTORDER_CREATED_DESC:
+            case self::SORTORDER_REPLIES_DESC:
+            case self::SORTORDER_DISCUSSION_DESC:
+            case self::SORTORDER_STARTER_DESC:
+            case self::SORTORDER_GROUP_DESC:
+            default:
+                return "DESC";
+        }
+    }
+
+    /**
+     * Get the sort order SQL for a sort method.
+     *
+     * @param int|null  $sortmethod
+     * @param bool|null $includefavourites
+     * @return string
+     */
+    private function get_sort_order(?int $sortmethod, bool $includefavourites = true): string {
+
+        $alias = $this->get_table_alias();
+        // TODO consider user favourites...
+        $keyfield = $this->get_keyfield($sortmethod);
+        $direction = $this->get_sort_direction($sortmethod);
+
+        $favouritesort = '';
+        if ($includefavourites) {
+            $favalias = $this->get_favourite_alias();
+            // Since we're joining on the favourite table any discussion that isn't favourited will have
+            // null in the favourite columns. Nulls behave differently in the sorting for different databases.
+            // We can ensure consistency between databases by explicitly deprioritising any null favourite field
+            // using a case statement.
+            $favouritesort = ", CASE WHEN {$favalias}.id IS NULL THEN 0 ELSE 1 END DESC";
+            // After the null favourite fields are deprioritised and appear below the favourited discussions we
+            // need to order the favourited discussions by id so that the most recently favourited discussions
+            // appear at the top of the list.
+            $favouritesort .= ", {$favalias}.itemtype DESC";
+        }
+
+        return "{$alias}.pinned DESC $favouritesort , {$keyfield} {$direction}, {$alias}.id {$direction}";
+    }
+
+    /**
+     * Fetch any required SQL to respect timed posts.
+     *
+     * @param   bool        $includehiddendiscussions Whether to include hidden discussions or not
+     * @param   int|null    $includepostsforuser Which user to include posts for, if any
+     * @return  array       The SQL and parameters to include
+     */
+    protected function get_hidden_post_sql(bool $includehiddendiscussions, ?int $includepostsforuser) {
+        $wheresql = '';
+        $params = [];
+        if (!$includehiddendiscussions) {
+            $now = time();
+            $wheresql = " AND ((d.timestart <= :timestart AND (d.timeend = 0 OR d.timeend > :timeend))";
+            $params['timestart'] = $now;
+            $params['timeend'] = $now;
+            if (null !== $includepostsforuser) {
+                $wheresql .= " OR d.userid = :byuser";
+                $params['byuser'] = $includepostsforuser;
+            }
+            $wheresql .= ")";
+        }
+
+        return [
+            'wheresql' => $wheresql,
+            'params' => $params,
+        ];
+    }
+
+    /**
+     * Get each discussion, first post, first and last post author for the given forum, considering timed posts, and
+     * pagination.
+     *
+     * @param   int         $forumid The forum to fetch the discussion set for
+     * @param   bool        $includehiddendiscussions Whether to include hidden discussions or not
+     * @param   int|null    $includepostsforuser Which user to include posts for, if any
+     * @param   int         $sortorder The sort order to use
+     * @param   int         $limit The number of discussions to fetch
+     * @param   int         $offset The record offset
+     * @return  array       The set of data fetched
+     */
+    public function get_from_forum_id(
+        int $forumid,
+        bool $includehiddendiscussions,
+        ?int $includepostsforuser,
+        ?int $sortorder,
+        int $limit,
+        int $offset
+    ) {
+        $alias = $this->get_table_alias();
+        $wheresql = "{$alias}.forum = :forumid";
+        [
+            'wheresql' => $hiddensql,
+            'params' => $hiddenparams
+        ] = $this->get_hidden_post_sql($includehiddendiscussions, $includepostsforuser);
+        $wheresql .= $hiddensql;
+
+        $params = array_merge($hiddenparams, [
+            'forumid' => $forumid,
+        ]);
+
+        $includefavourites = $includepostsforuser ? true : false;
+        $sql = $this->generate_get_records_sql($wheresql, $this->get_sort_order($sortorder, $includefavourites),
+            $includepostsforuser);
+        $records = $this->get_db()->get_records_sql($sql, $params, $offset, $limit);
+
+        return $this->transform_db_records_to_entities($records);
+    }
+
+    /**
+     * Get each discussion, first post, first and last post author for the given forum, and the set of groups to display
+     * considering timed posts, and pagination.
+     *
+     * @param   int         $forumid The forum to fetch the discussion set for
+     * @param   int[]       $groupids The list of real groups to filter on
+     * @param   bool        $includehiddendiscussions Whether to include hidden discussions or not
+     * @param   int|null    $includepostsforuser Which user to include posts for, if any
+     * @param   int         $sortorder The sort order to use
+     * @param   int         $limit The number of discussions to fetch
+     * @param   int         $offset The record offset
+     * @return  array       The set of data fetched
+     */
+    public function get_from_forum_id_and_group_id(
+        int $forumid,
+        array $groupids,
+        bool $includehiddendiscussions,
+        ?int $includepostsforuser,
+        ?int $sortorder,
+        int $limit,
+        int $offset
+    ) {
+        $alias = $this->get_table_alias();
+
+        $wheresql = "{$alias}.forum = :forumid AND ";
+        $groupparams = [];
+        if (empty($groupids)) {
+            $wheresql .= "{$alias}.groupid = :allgroupsid";
+        } else {
+            list($insql, $groupparams) = $this->get_db()->get_in_or_equal($groupids, SQL_PARAMS_NAMED, 'gid');
+            $wheresql .= "({$alias}.groupid = :allgroupsid OR {$alias}.groupid {$insql})";
+        }
+
+        [
+            'wheresql' => $hiddensql,
+            'params' => $hiddenparams
+        ] = $this->get_hidden_post_sql($includehiddendiscussions, $includepostsforuser);
+        $wheresql .= $hiddensql;
+
+        $params = array_merge($hiddenparams, $groupparams, [
+            'forumid' => $forumid,
+            'allgroupsid' => -1,
+        ]);
+
+        $includefavourites = $includepostsforuser ? true : false;
+        $sql = $this->generate_get_records_sql($wheresql, $this->get_sort_order($sortorder, $includefavourites),
+            $includepostsforuser);
+        $records = $this->get_db()->get_records_sql($sql, $params, $offset, $limit);
+
+        return $this->transform_db_records_to_entities($records);
+    }
+
+    /**
+     * Count the number of discussions in the forum.
+     *
+     * @param int $forumid Id of the forum to count discussions in
+     * @param bool $includehiddendiscussions Include hidden dicussions in the count?
+     * @param int|null $includepostsforuser Include discussions created by this user in the count
+     *                                      (only works if not including hidden discussions).
+     * @return int
+     */
+    public function get_total_discussion_count_from_forum_id(
+        int $forumid,
+        bool $includehiddendiscussions,
+        ?int $includepostsforuser
+    ) {
+        $alias = $this->get_table_alias();
+
+        $wheresql = "{$alias}.forum = :forumid";
+
+        [
+            'wheresql' => $hiddensql,
+            'params' => $hiddenparams
+        ] = $this->get_hidden_post_sql($includehiddendiscussions, $includepostsforuser);
+        $wheresql .= $hiddensql;
+
+        $params = array_merge($hiddenparams, [
+            'forumid' => $forumid,
+        ]);
+
+        return $this->get_db()->count_records_sql($this->generate_count_records_sql($wheresql), $params);
+    }
+
+    /**
+     * Count the number of discussions in all groups and the list of groups provided.
+     *
+     * @param int $forumid Id of the forum to count discussions in
+     * @param int[] $groupids List of group ids to include in the count (discussions in all groups will always be counted)
+     * @param bool $includehiddendiscussions Include hidden dicussions in the count?
+     * @param int|null $includepostsforuser Include discussions created by this user in the count
+     *                                      (only works if not including hidden discussions).
+     * @return int
+     */
+    public function get_total_discussion_count_from_forum_id_and_group_id(
+        int $forumid,
+        array $groupids,
+        bool $includehiddendiscussions,
+        ?int $includepostsforuser
+    ) {
+        $alias = $this->get_table_alias();
+
+        $wheresql = "{$alias}.forum = :forumid AND ";
+        $groupparams = [];
+        if (empty($groupids)) {
+            $wheresql .= "{$alias}.groupid = :allgroupsid";
+        } else {
+            list($insql, $groupparams) = $this->get_db()->get_in_or_equal($groupids, SQL_PARAMS_NAMED, 'gid');
+            $wheresql .= "({$alias}.groupid = :allgroupsid OR {$alias}.groupid {$insql})";
+        }
+
+        [
+            'wheresql' => $hiddensql,
+            'params' => $hiddenparams
+        ] = $this->get_hidden_post_sql($includehiddendiscussions, $includepostsforuser);
+        $wheresql .= $hiddensql;
+
+        $params = array_merge($hiddenparams, $groupparams, [
+            'forumid' => $forumid,
+            'allgroupsid' => -1,
+        ]);
+
+        return $this->get_db()->count_records_sql($this->generate_count_records_sql($wheresql), $params);
+    }
+
+    /**
+     * Get the standard favouriting sql.
+     *
+     * @param int $userid The ID of the user we are getting the sql for
+     * @return [$sql, $params] An array comprising of the sql and any associated params
+     */
+    private function get_favourite_sql(int $userid): array {
+
+        $usercontext = \context_user::instance($userid);
+        $alias = $this->get_table_alias();
+        $ufservice = \core_favourites\service_factory::get_service_for_user_context($usercontext);
+        list($favsql, $favparams) = $ufservice->get_join_sql_by_type('mod_forum', 'discussions',
+            $this->get_favourite_alias(), "$alias.id");
+
+        return [$favsql, $favparams];
+    }
+}

mod/forum/classes/local/vaults/forum.php

@@ -0,0 +1,199 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Forum vault class.
+ *
+ * @package    mod_forum
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_forum\local\vaults;
+
+defined('MOODLE_INTERNAL') || die();
+
+use mod_forum\local\entities\forum as forum_entity;
+use mod_forum\local\vaults\preprocessors\extract_context as extract_context_preprocessor;
+use mod_forum\local\vaults\preprocessors\extract_record as extract_record_preprocessor;
+use core\dml\table as dml_table;
+use context_helper;
+
+/**
+ * Forum vault class.
+ *
+ * This should be the only place that accessed the database.
+ *
+ * This uses the repository pattern. See:
+ * https://designpatternsphp.readthedocs.io/en/latest/More/Repository/README.html
+ *
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class forum extends db_table_vault {
+    /** The table for this vault */
+    private const TABLE = 'forum';
+
+    /**
+     * Get the table alias.
+     *
+     * @return string
+     */
+    protected function get_table_alias(): string {
+        return 'f';
+    }
+
+    /**
+     * Build the SQL to be used in get_records_sql.
+     *
+     * @param string|null $wheresql Where conditions for the SQL
+     * @param string|null $sortsql Order by conditions for the SQL
+     * @param int|null $userid The user ID
+     * @return string
+     */
+    protected function generate_get_records_sql(string $wheresql = null, string $sortsql = null, ?int $userid = null): string {
+        $db = $this->get_db();
+        $alias = $this->get_table_alias();
+
+        $thistable = new dml_table(self::TABLE, $alias, $alias);
+        $cmtable = new dml_table('course_modules', 'cm', 'cm_');
+        $coursetable = new dml_table('course', 'c', 'c_');
+
+        $fields = implode(', ', [
+            $thistable->get_field_select(),
+            context_helper::get_preload_record_columns_sql('ctx'),
+            $cmtable->get_field_select(),
+            $coursetable->get_field_select(),
+        ]);
+
+        $tables = $thistable->get_from_sql();
+        $tables .= " JOIN {modules} m ON m.name = 'forum'";
+        $tables .= " JOIN " . $cmtable->get_from_sql() . " ON cm.module = m.id AND cm.instance = {$alias}.id";
+        $tables .= ' JOIN {context} ctx ON ctx.contextlevel = ' . CONTEXT_MODULE .  ' AND ctx.instanceid = cm.id';
+        $tables .= " JOIN " . $coursetable->get_from_sql() . " ON c.id = {$alias}.course";
+
+        $selectsql = 'SELECT ' . $fields . ' FROM ' . $tables;
+        $selectsql .= $wheresql ? ' WHERE ' . $wheresql : '';
+        $selectsql .= $sortsql ? ' ORDER BY ' . $sortsql : '';
+
+        return $selectsql;
+    }
+
+    /**
+     * Get a list of preprocessors to execute on the DB results before being converted
+     * into entities.
+     *
+     * @return array
+     */
+    protected function get_preprocessors(): array {
+        return array_merge(
+            parent::get_preprocessors(),
+            [
+                'forum' => new extract_record_preprocessor(self::TABLE, $this->get_table_alias()),
+                'course_module' => new extract_record_preprocessor('course_modules', 'cm_'),
+                'course' => new extract_record_preprocessor('course', 'c_'),
+                'context' => new extract_context_preprocessor(),
+            ]
+        );
+    }
+
+    /**
+     * Convert the DB records into forum entities.
+     *
+     * @param array $results The DB records
+     * @return forum_entity[]
+     */
+    protected function from_db_records(array $results): array {
+        $entityfactory = $this->get_entity_factory();
+
+        return array_map(function(array $result) use ($entityfactory) {
+            [
+                'forum' => $forumrecord,
+                'course_module' => $coursemodule,
+                'course' => $course,
+                'context' => $context,
+            ] = $result;
+            return $entityfactory->get_forum_from_stdclass($forumrecord, $context, $coursemodule, $course);
+        }, $results);
+    }
+
+    /**
+     * Get the forum for the given course module id.
+     *
+     * @param int $id The course module id
+     * @return forum_entity|null
+     */
+    public function get_from_course_module_id(int $id): ?forum_entity {
+        $records = $this->get_from_course_module_ids([$id]);
+        return count($records) ? array_shift($records) : null;
+    }
+
+    /**
+     * Get the forums for the given course module ids
+     *
+     * @param int[] $ids The course module ids
+     * @return forum_entity[]
+     */
+    public function get_from_course_module_ids(array $ids): array {
+        $alias = $this->get_table_alias();
+        list($insql, $params) = $this->get_db()->get_in_or_equal($ids);
+        $wheresql = 'cm.id ' . $insql;
+        $sql = $this->generate_get_records_sql($wheresql);
+        $records = $this->get_db()->get_records_sql($sql, $params);
+
+        return $this->transform_db_records_to_entities($records);
+    }
+
+    /**
+     * Get the forum entity for the given post id.
+     *
+     * @param int $id The course module id
+     * @return forum_entity|null
+     */
+    public function get_from_post_id(int $id): ?forum_entity {
+        $alias = $this->get_table_alias();
+        $thistable = new dml_table(self::TABLE, $alias, $alias);
+        $coursemoduletable = new dml_table('course_modules', 'cm', 'cm_');
+        $coursetable = new dml_table('course', 'c', 'c_');
+
+        $tablefields = $thistable->get_field_select();
+        $coursemodulefields = $coursemoduletable->get_field_select();
+        $coursefields = $coursetable->get_field_select();
+
+        $fields = implode(', ', [
+            $tablefields,
+            context_helper::get_preload_record_columns_sql('ctx'),
+            $coursemodulefields,
+            $coursefields,
+        ]);
+
+        $tables = "{forum_posts} p";
+        $tables .= " JOIN {forum_discussions} d ON d.id = p.discussion";
+        $tables .= ' JOIN {' . self::TABLE . "} {$alias} ON {$alias}.id = d.forum";
+        $tables .= " JOIN {modules} m ON m.name = 'forum'";
+        $tables .= " JOIN {course_modules} cm ON cm.module = m.id AND cm.instance = {$alias}.id";
+        $tables .= ' JOIN {context} ctx ON ctx.contextlevel = ' . CONTEXT_MODULE .  ' AND ctx.instanceid = cm.id';
+        $tables .= " JOIN {course} c ON c.id = {$alias}.course";
+
+        $sql = "SELECT {$fields} FROM {$tables} WHERE p.id = :postid";
+        $records = $this->get_db()->get_records_sql($sql, [
+            'postid' => $id,
+        ]);
+
+        $records = $this->transform_db_records_to_entities($records);
+        return count($records) ? array_shift($records) : null;
+    }
+}

mod/forum/classes/local/vaults/post.php

@@ -0,0 +1,551 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Post vault class.
+ *
+ * @package    mod_forum
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_forum\local\vaults;
+
+defined('MOODLE_INTERNAL') || die();
+
+use mod_forum\local\entities\forum as forum_entity;
+use mod_forum\local\entities\post as post_entity;
+use mod_forum\local\factories\entity as entity_factory;
+use stdClass;
+
+/**
+ * Post vault class.
+ *
+ * This should be the only place that accessed the database.
+ *
+ * This class should not return any objects other than post_entity objects. The class
+ * may contain some utility count methods which return integers.
+ *
+ * This uses the repository pattern. See:
+ * https://designpatternsphp.readthedocs.io/en/latest/More/Repository/README.html
+ *
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class post extends db_table_vault {
+    /** The table for this vault */
+    private const TABLE = 'forum_posts';
+    /** Alias for user id */
+    private const USER_ID_ALIAS = 'userpictureid';
+    /** Alias for user fields */
+    private const USER_ALIAS = 'userrecord';
+
+    /**
+     * Get the table alias.
+     *
+     * @return string
+     */
+    protected function get_table_alias(): string {
+        return 'p';
+    }
+
+    /**
+     * Build the SQL to be used in get_records_sql.
+     *
+     * @param string|null $wheresql Where conditions for the SQL
+     * @param string|null $sortsql Order by conditions for the SQL
+     * @param int|null $userid The user ID
+     * @return string
+     */
+    protected function generate_get_records_sql(string $wheresql = null, string $sortsql = null, ?int $userid = null): string {
+        $table = self::TABLE;
+        $alias = $this->get_table_alias();
+        $fields = $alias . '.*';
+        $tables = "{{$table}} {$alias}";
+
+        $selectsql = "SELECT {$fields} FROM {$tables}";
+        $selectsql .= $wheresql ? ' WHERE ' . $wheresql : '';
+        $selectsql .= $sortsql ? ' ORDER BY ' . $sortsql : '';
+
+        return $selectsql;
+    }
+
+    /**
+     * Convert the DB records into post entities.
+     *
+     * @param array $results The DB records
+     * @return post_entity[]
+     */
+    protected function from_db_records(array $results) {
+        $entityfactory = $this->get_entity_factory();
+
+        return array_map(function(array $result) use ($entityfactory) {
+            ['record' => $record] = $result;
+            return $entityfactory->get_post_from_stdclass($record);
+        }, $results);
+    }
+
+    /**
+     * Get the post ids for the given discussion.
+     *
+     * @param stdClass $user The user to check the unread count for
+     * @param int $discussionid The discussion to load posts for
+     * @param bool $canseeprivatereplies Whether this user can see all private replies or not
+     * @param string $orderby Order the results
+     * @return post_entity[]
+     */
+    public function get_from_discussion_id(
+        stdClass $user,
+        int $discussionid,
+        bool $canseeprivatereplies,
+        string $orderby = 'created ASC'
+    ): array {
+        return $this->get_from_discussion_ids($user, [$discussionid], $canseeprivatereplies, $orderby);
+    }
+
+    /**
+     * Get the list of posts for the given discussions.
+     *
+     * @param stdClass $user The user to load posts for.
+     * @param int[] $discussionids The list of discussion ids to load posts for
+     * @param bool $canseeprivatereplies Whether this user can see all private replies or not
+     * @param string $orderby Order the results
+     * @return post_entity[]
+     */
+    public function get_from_discussion_ids(
+        stdClass $user,
+        array $discussionids,
+        bool $canseeprivatereplies,
+        string $orderby = ''
+    ): array {
+        if (empty($discussionids)) {
+            return [];
+        }
+
+        return $this->get_from_filters($user, ['discussionids' => $discussionids], $canseeprivatereplies, $orderby);
+    }
+
+    /**
+     * The method returns posts based on a set of filters.
+     *
+     * @param stdClass $user Only used when restricting private replies
+     * @param array $filters Export filters, valid filters are:
+     *
+     * 'discussionids' => array of discussion ids eg [1,2,3]
+     * 'userids' => array of user ids eg [1,2,3]
+     * 'from' => timestamp to filter posts from this date.
+     *  'to' => timestamp to filter posts till this date.
+     *
+     * @param bool $canseeprivatereplies Whether this user can see all private replies or not
+     * @param string $orderby Order the results
+     * @return post_entity[]
+     */
+    public function get_from_filters(
+            stdClass $user,
+            array $filters,
+            bool $canseeprivatereplies,
+            string $orderby = ''
+    ): array {
+        if (count($filters) == 0) {
+            return [];
+        }
+        $wheresql = [];
+        $params = [];
+        $alias = $this->get_table_alias();
+
+        // Filter by discussion ids.
+        if (!empty($filters['discussionids'])) {
+            list($indiscussionssql, $indiscussionsparams) = $this->get_db()->get_in_or_equal($filters['discussionids'],
+                SQL_PARAMS_NAMED);
+            $wheresql[] = "{$alias}.discussion {$indiscussionssql}";
+            $params += $indiscussionsparams;
+        }
+
+        // Filter by user ids.
+        if (!empty($filters['userids'])) {
+            list($inuserssql, $inusersparams) = $this->get_db()->get_in_or_equal($filters['userids'],
+                SQL_PARAMS_NAMED);
+            $wheresql[] = "{$alias}.userid {$inuserssql}";
+            $params += $inusersparams;
+        }
+
+        // Filter posts by from and to dates.
+        if (isset($filters['from'])) {
+            $wheresql[] = "{$alias}.created >= :from";
+            $params['from'] = $filters['from'];
+        }
+
+        if (isset($filters['to'])) {
+            $wheresql[] = "{$alias}.created < :to";
+            $params['to'] = $filters['to'];
+        }
+
+        // We need to build the WHERE here, because get_private_reply_sql returns the query with the AND clause.
+        $wheresql = implode(' AND ', $wheresql);
+
+        // Build private replies sql.
+        [
+            'where' => $privatewhere,
+            'params' => $privateparams,
+        ] = $this->get_private_reply_sql($user, $canseeprivatereplies);
+        $wheresql .= "{$privatewhere}";
+        $params += $privateparams;
+
+        if ($orderby) {
+            $orderbysql = $alias . '.' . $orderby;
+        } else {
+            $orderbysql = '';
+        }
+
+        $sql = $this->generate_get_records_sql($wheresql, $orderbysql);
+        $records = $this->get_db()->get_records_sql($sql, $params);
+
+        return $this->transform_db_records_to_entities($records);
+    }
+
+    /**
+     * Load a list of replies to the given post. This will load all descendants of the post.
+     * That is, all direct replies and replies to those replies etc.
+     *
+     * The return value will be a flat array of posts in the requested order.
+     *
+     * @param stdClass    $user The user to check the unread count for
+     * @param post_entity $post The post to load replies for
+     * @param bool        $canseeprivatereplies Whether this user can see all private replies or not
+     * @param string $orderby How to order the replies
+     * @return post_entity[]
+     */
+    public function get_replies_to_post(
+        stdClass $user,
+        post_entity $post,
+        bool $canseeprivatereplies,
+        string $orderby = 'created ASC'
+    ): array {
+        $alias = $this->get_table_alias();
+
+        [
+            'where' => $privatewhere,
+            'params' => $privateparams,
+        ] = $this->get_private_reply_sql($user, $canseeprivatereplies);
+
+        $params = array_merge([
+            'discussionid' => $post->get_discussion_id(),
+            'created' => $post->get_time_created(),
+            'excludepostid' => $post->get_id(),
+        ], $privateparams);
+
+        // Unfortunately the best we can do to filter down the query is ignore all posts
+        // that were created before the given post (since they can't be replies).
+        // We also filter to remove private replies if the user cannot vie them.
+        $wheresql = "{$alias}.discussion = :discussionid
+                 AND {$alias}.created >= :created {$privatewhere}
+                 AND {$alias}.id != :excludepostid";
+        $orderbysql = $alias . '.' . $orderby;
+        $sql = $this->generate_get_records_sql($wheresql, $orderbysql);
+        $records = $this->get_db()->get_records_sql($sql, $params);
+        $posts = $this->transform_db_records_to_entities($records);
+        $sorter = $this->get_entity_factory()->get_posts_sorter();
+
+        // We need to sort all of the values into the replies tree in order to capture
+        // the full list of descendants.
+        $sortedposts = $sorter->sort_into_children($posts);
+        $replies = [];
+
+        // From the sorted list we can grab the first elements and check if they are replies
+        // to the post we care about. If so we keep them.
+        foreach ($sortedposts as $candidate) {
+            [$candidatepost, $candidatereplies] = $candidate;
+            if ($candidatepost->has_parent() && $candidatepost->get_parent_id() == $post->get_id()) {
+                $replies[] = $candidate;
+            }
+        }
+
+        if (empty($replies)) {
+            return $replies;
+        }
+
+        $getreplypostids = function($candidates) use (&$getreplypostids) {
+            $ids = [];
+
+            foreach ($candidates as $candidate) {
+                [$reply, $replies] = $candidate;
+                $ids = array_merge($ids, [$reply->get_id()], $getreplypostids($replies));
+            }
+
+            return $ids;
+        };
+        // Recursively build a list of the ids of all posts in the full reply tree.
+        $replypostids = $getreplypostids($replies);
+
+        // Now go back and filter the original result set down to just the posts that
+        // we've flagged as in the reply tree. We need to filter the original set of values
+        // so that we can maintain the requested sort order.
+        return array_values(array_filter($posts, function($post) use ($replypostids) {
+            return in_array($post->get_id(), $replypostids);
+        }));
+    }
+
+    /**
+     * Get a mapping of replies to the specified discussions.
+     *
+     * @param   stdClass    $user The user to check the unread count for
+     * @param   int[]       $discussionids The list of discussions to fetch counts for
+     * @param   bool        $canseeprivatereplies Whether this user can see all private replies or not
+     * @return  int[]       The number of replies for each discussion returned in an associative array
+     */
+    public function get_reply_count_for_discussion_ids(stdClass $user, array $discussionids, bool $canseeprivatereplies): array {
+        if (empty($discussionids)) {
+            return [];
+        }
+
+        list($insql, $params) = $this->get_db()->get_in_or_equal($discussionids, SQL_PARAMS_NAMED);
+
+        [
+            'where' => $privatewhere,
+            'params' => $privateparams,
+        ] = $this->get_private_reply_sql($user, $canseeprivatereplies);
+
+        $sql = "SELECT discussion, COUNT(1)
+                  FROM {" . self::TABLE . "} p
+                 WHERE p.discussion {$insql} AND p.parent > 0 {$privatewhere}
+                 GROUP BY discussion";
+
+        return $this->get_db()->get_records_sql_menu($sql, array_merge($params, $privateparams));
+    }
+
+    /**
+     * Get a mapping of replies to the specified discussions.
+     *
+     * @param   stdClass    $user The user to check the unread count for
+     * @param   int         $postid The post to collect replies to
+     * @param   int         $discussionid The list of discussions to fetch counts for
+     * @param   bool        $canseeprivatereplies Whether this user can see all private replies or not
+     * @return  int         The number of replies for each discussion returned in an associative array
+     */
+    public function get_reply_count_for_post_id_in_discussion_id(
+            stdClass $user, int $postid, int $discussionid, bool $canseeprivatereplies): int {
+        [
+            'where' => $privatewhere,
+            'params' => $privateparams,
+        ] = $this->get_private_reply_sql($user, $canseeprivatereplies);
+
+        $alias = $this->get_table_alias();
+        $table = self::TABLE;
+
+        $sql = "SELECT {$alias}.id, {$alias}.parent
+                  FROM {{$table}} {$alias}
+                 WHERE p.discussion = :discussionid {$privatewhere}";
+
+        $postparents = $this->get_db()->get_records_sql_menu($sql, array_merge([
+                'discussionid' => $discussionid,
+            ], $privateparams));
+
+        return $this->count_children_from_parent_recursively($postparents, $postid);
+    }
+
+    /**
+     * Count the children whose parent matches the current record recursively.
+     *
+     * @param   array   $postparents The full mapping of posts.
+     * @param   int     $postid The ID to check for
+     * @return  int     $count
+     */
+    private function count_children_from_parent_recursively(array $postparents, int $postid): int {
+        if (!isset($postparents[$postid])) {
+            // Post not found at all.
+            return 0;
+        }
+
+        $count = 0;
+        foreach ($postparents as $pid => $parentid) {
+            if ($postid == $parentid) {
+                $count += $this->count_children_from_parent_recursively($postparents, $pid) + 1;
+            }
+        }
+
+        return $count;
+    }
+
+    /**
+     * Get a mapping of unread post counts for the specified discussions.
+     *
+     * @param   stdClass    $user The user to fetch counts for
+     * @param   int[]       $discussionids The list of discussions to fetch counts for
+     * @param   bool        $canseeprivatereplies Whether this user can see all private replies or not
+     * @return  int[]       The count of unread posts for each discussion returned in an associative array
+     */
+    public function get_unread_count_for_discussion_ids(stdClass $user, array $discussionids, bool $canseeprivatereplies): array {
+        global $CFG;
+
+        if (empty($discussionids)) {
+            return [];
+        }
+
+        [
+            'where' => $privatewhere,
+            'params' => $privateparams,
+        ] = $this->get_private_reply_sql($user, $canseeprivatereplies);
+
+        $alias = $this->get_table_alias();
+        list($insql, $params) = $this->get_db()->get_in_or_equal($discussionids, SQL_PARAMS_NAMED);
+        $sql = "SELECT p.discussion, COUNT(p.id) FROM {" . self::TABLE . "} p
+             LEFT JOIN {forum_read} r ON r.postid = p.id AND r.userid = :userid
+                 WHERE p.discussion {$insql} AND p.modified > :cutofftime AND r.id IS NULL {$privatewhere}
+              GROUP BY p.discussion";
+
+        $params['userid'] = $user->id;
+        $params['cutofftime'] = floor((new \DateTime())
+            ->sub(new \DateInterval("P{$CFG->forum_oldpostdays}D"))
+            ->format('U') / 60) * 60;
+
+        return $this->get_db()->get_records_sql_menu($sql, array_merge($params, $privateparams));
+    }
+
+    /**
+     * Get a mapping of the most recent post record in each discussion based on post creation time.
+     *
+     * @param stdClass $user
+     * @param array $discussionids
+     * @param bool $canseeprivatereplies
+     * @return array
+     * @throws \coding_exception
+     * @throws \dml_exception
+     */
+    public function get_latest_posts_for_discussion_ids(
+        stdClass $user, array $discussionids, bool $canseeprivatereplies): array {
+
+        if (empty($discussionids)) {
+            return [];
+        }
+
+        list($insql, $params) = $this->get_db()->get_in_or_equal($discussionids, SQL_PARAMS_NAMED);
+
+        [
+            'where' => $privatewhere,
+            'params' => $privateparams,
+        ] = $this->get_private_reply_sql($user, $canseeprivatereplies, "mp");
+
+        $sql = "
+            SELECT posts.*
+            FROM {" . self::TABLE . "} posts
+            JOIN (
+                SELECT p.discussion, MAX(p.id) as latestpostid
+                FROM {" . self::TABLE . "} p
+                JOIN (
+                    SELECT mp.discussion, MAX(mp.created) AS created
+                      FROM {" . self::TABLE . "} mp
+                     WHERE mp.discussion {$insql} {$privatewhere}
+                  GROUP BY mp.discussion
+                ) lp ON lp.discussion = p.discussion AND lp.created = p.created
+            GROUP BY p.discussion
+          ) plp on plp.discussion = posts.discussion AND plp.latestpostid = posts.id";
+
+        $records = $this->get_db()->get_records_sql($sql, array_merge($params, $privateparams));
+        $entities = $this->transform_db_records_to_entities($records);
+
+        return array_reduce($entities, function($carry, $entity) {
+            $carry[$entity->get_discussion_id()] = $entity;
+            return $carry;
+        }, []);
+    }
+
+    /**
+     * Get the SQL where and additional parameters to use to restrict posts to private reply posts.
+     *
+     * @param   stdClass    $user The user to fetch counts for
+     * @param   bool        $canseeprivatereplies Whether this user can see all private replies or not
+     * @return  array       The SQL WHERE clause, and parameters to use in the SQL.
+     */
+    private function get_private_reply_sql(stdClass $user, bool $canseeprivatereplies, $posttablealias = "p") {
+        $params = [];
+        $privatewhere = '';
+        if (!$canseeprivatereplies) {
+            $privatewhere = " AND ({$posttablealias}.privatereplyto = :privatereplyto OR " .
+                "{$posttablealias}.userid = :privatereplyfrom OR {$posttablealias}.privatereplyto = 0)";
+            $params['privatereplyto'] = $user->id;
+            $params['privatereplyfrom'] = $user->id;
+        }
+
+        return [
+            'where' => $privatewhere,
+            'params' => $params,
+        ];
+    }
+
+    /**
+     * Get a mapping of the first post in each discussion based on post creation time.
+     *
+     * @param   int[]         $discussionids The list of discussions to fetch counts for
+     * @return  post_entity[] The post object of the first post for each discussions returned in an associative array
+     */
+    public function get_first_post_for_discussion_ids(array $discussionids): array {
+
+        if (empty($discussionids)) {
+            return [];
+        }
+
+        list($insql, $params) = $this->get_db()->get_in_or_equal($discussionids, SQL_PARAMS_NAMED);
+
+        $sql = "
+            SELECT p.*
+              FROM {" . self::TABLE . "} p
+              JOIN (
+                SELECT mp.discussion, MIN(mp.created) AS created
+                  FROM {" . self::TABLE . "} mp
+                 WHERE mp.discussion {$insql}
+              GROUP BY mp.discussion
+              ) lp ON lp.discussion = p.discussion AND lp.created = p.created";
+
+        $records = $this->get_db()->get_records_sql($sql, $params);
+        return $this->transform_db_records_to_entities($records);
+    }
+
+    /**
+     * Get the posts for the given user.
+     *
+     * @param int $discussionid The discussion to fetch posts for
+     * @param int $userid The user to fetch posts for
+     * @param bool $canseeprivatereplies Whether this user can see all private replies or not
+     * @param string $orderby Order the results
+     * @return post_entity[]
+     */
+    public function get_posts_in_discussion_for_user_id(
+        int $discussionid,
+        int $userid,
+        bool $canseeprivatereplies,
+        string $orderby = 'created ASC'
+    ): array {
+        $user = $this->get_db()->get_record('user', ['id' => (int)$userid], '*', IGNORE_MISSING);
+
+        $alias = $this->get_table_alias();
+        [
+            'where' => $privatewhere,
+            'params' => $privateparams,
+        ] = $this->get_private_reply_sql($user, $canseeprivatereplies);
+
+        $wheresql = "{$alias}.userid = :authorid AND
+                     {$alias}.discussion = :discussionid {$privatewhere}";
+        $orderbysql = $alias . '.' . $orderby;
+
+        $sql = $this->generate_get_records_sql($wheresql, $orderbysql);
+        $records = $this->get_db()->get_records_sql($sql, array_merge([
+            'authorid' => $userid,
+            'discussionid' => $discussionid
+        ], $privateparams));
+
+        return $this->transform_db_records_to_entities($records);
+    }
+}

mod/forum/classes/local/vaults/post_attachment.php

@@ -0,0 +1,120 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Post attachment vault class.
+ *
+ * @package    mod_forum
+ * @copyright  2018 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_forum\local\vaults;
+
+defined('MOODLE_INTERNAL') || die();
+
+use mod_forum\local\entities\post as post_entity;
+use context;
+use file_storage;
+
+/**
+ * Post attachment vault class.
+ *
+ * This should be the only place that accessed the database.
+ *
+ * This uses the repository pattern. See:
+ * https://designpatternsphp.readthedocs.io/en/latest/More/Repository/README.html
+ *
+ * @copyright  2018 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class post_attachment {
+    /** The component for attachments */
+    private const COMPONENT = 'mod_forum';
+    /** Sort the attachments by filename */
+    private const SORT = 'filename';
+    /** Don't include directories */
+    private const INCLUDE_DIRECTORIES = false;
+    /** @var file_storage $filestorage File storage */
+    private $filestorage;
+
+    /**
+     * Construct.
+     *
+     * @param file_storage $filestorage File storage
+     */
+    public function __construct(file_storage $filestorage) {
+        $this->filestorage = $filestorage;
+    }
+
+    /**
+     * Get the attachments for the given posts. The results are indexed by
+     * post id.
+     *
+     * @param context $context The (forum) context that the posts are in
+     * @param post_entity[] $posts The list of posts to load attachments for
+     * @param string $area The file storage area, can be 'attachment' or 'post' for inline attachments.
+     * @return array Post attachments indexed by post id
+     */
+    private function get_area_attachments_for_posts(context $context, array $posts, string $area) {
+        $itemids = array_map(function($post) {
+            return $post->get_id();
+        }, $posts);
+
+        $files = $this->filestorage->get_area_files(
+            $context->id,
+            self::COMPONENT,
+            $area,
+            $itemids,
+            self::SORT,
+            self::INCLUDE_DIRECTORIES
+        );
+
+        $filesbyid = array_reduce($posts, function($carry, $post) {
+            $carry[$post->get_id()] = [];
+            return $carry;
+        }, []);
+
+        return array_reduce($files, function($carry, $file) {
+            $itemid = $file->get_itemid();
+            $carry[$itemid] = array_merge($carry[$itemid], [$file]);
+            return $carry;
+        }, $filesbyid);
+    }
+
+    /**
+     * Get attachment for posts.
+     *
+     * @param context $context The (forum) context that the posts are in
+     * @param post_entity[] $posts The list of posts to load attachments for
+     * @return array Post attachments indexed by post id
+     */
+    public function get_attachments_for_posts(context $context, array $posts) {
+        return $this->get_area_attachments_for_posts($context, $posts, 'attachment');
+    }
+
+    /**
+     * Get inline attachments for posts.
+     *
+     * @param context $context The (forum) context that the posts are in
+     * @param post_entity[] $posts The list of posts to load attachments for
+     * @return array Post attachments indexed by post id
+     */
+    public function get_inline_attachments_for_posts(context $context, array $posts) {
+        return $this->get_area_attachments_for_posts($context, $posts, 'post');
+    }
+
+}

mod/forum/classes/local/vaults/post_read_receipt_collection.php

@@ -0,0 +1,121 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Post read receipt collection class.
+ *
+ * @package    mod_forum
+ * @copyright  2018 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_forum\local\vaults;
+
+defined('MOODLE_INTERNAL') || die();
+
+use stdClass;
+
+/**
+ * Post read receipt collection class.
+ *
+ * This should be the only place that accessed the database.
+ *
+ * This uses the repository pattern. See:
+ * https://designpatternsphp.readthedocs.io/en/latest/More/Repository/README.html
+ *
+ * @copyright  2018 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class post_read_receipt_collection extends db_table_vault {
+    /** The table for this vault */
+    private const TABLE = 'forum_read';
+
+    /**
+     * Get the table alias.
+     *
+     * @return string
+     */
+    protected function get_table_alias(): string {
+        return 'fr';
+    }
+
+    /**
+     * Build the SQL to be used in get_records_sql.
+     *
+     * @param string|null $wheresql Where conditions for the SQL
+     * @param string|null $sortsql Order by conditions for the SQL
+     * @param int|null $userid The user ID
+     * @return string
+     */
+    protected function generate_get_records_sql(string $wheresql = null, string $sortsql = null, ?int $userid = null): string {
+        $selectsql = 'SELECT * FROM {' . self::TABLE . '} ' . $this->get_table_alias();
+        $selectsql .= $wheresql ? ' WHERE ' . $wheresql : '';
+        $selectsql .= $sortsql ? ' ORDER BY ' . $sortsql : '';
+
+        return $selectsql;
+    }
+
+    /**
+     * Convert the DB records into post_read_receipt_collection entities.
+     *
+     * @param array $results The DB records
+     * @return post_read_receipt_collection
+     */
+    protected function from_db_records(array $results) {
+        $entityfactory = $this->get_entity_factory();
+        $records = array_map(function($result) {
+            return $result['record'];
+        }, $results);
+
+        return $entityfactory->get_post_read_receipt_collection_from_stdclasses($records);
+    }
+
+    /**
+     * Load the post_read_receipt_collection for the given user and set
+     * of posts.
+     *
+     * @param int $userid Id of the user to load receipts for
+     * @param int[] $postids List of post ids to load receipts for
+     * @return post_read_receipt_collection
+     */
+    public function get_from_user_id_and_post_ids(int $userid, array $postids) {
+        $alias = $this->get_table_alias();
+        [$postidinsql, $params] = $this->get_db()->get_in_or_equal($postids);
+        $params[] = $userid;
+
+        $wheresql = "{$alias}.postid {$postidinsql}";
+        $wheresql .= " AND {$alias}.userid = ?";
+        $sql = $this->generate_get_records_sql($wheresql);
+        $records = $this->get_db()->get_records_sql($sql, $params);
+
+        return $this->transform_db_records_to_entities($records);
+    }
+
+    /**
+     * Load the post_read_receipt_collection for the given user and set
+     * of posts.
+     *
+     * @param stdClass $user The user to load receipts for
+     * @param post_entity[] $posts List of posts to load receipts for
+     * @return post_read_receipt_collection
+     */
+    public function get_from_user_and_posts(stdClass $user, array $posts) {
+        $postids = array_map(function($post) {
+            return $post->get_id();
+        }, $posts);
+        return $this->get_from_user_id_and_post_ids($user->id, $postids);
+    }
+}

mod/forum/classes/local/vaults/preprocessors/extract_context.php

@@ -0,0 +1,53 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Extract context vault preprocessor.
+ *
+ * @package    mod_forum
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_forum\local\vaults\preprocessors;
+
+defined('MOODLE_INTERNAL') || die();
+
+use context;
+use context_helper;
+
+/**
+ * Extract context vault preprocessor.
+ *
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class extract_context {
+    /**
+     * Extract the contexts from a list of records.
+     *
+     * @param stdClass[] $records The list of records which have context properties
+     * @return context[] List of contexts matching the records.
+     */
+    public function execute(array $records): array {
+        return array_map(function($record) {
+            $contextid = $record->ctxid;
+            context_helper::preload_from_record($record);
+            $context = context::instance_by_id($contextid);
+            return $context;
+        }, $records);
+    }
+}

mod/forum/classes/local/vaults/preprocessors/extract_record.php

@@ -0,0 +1,67 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Extract record vault preprocessor.
+ *
+ * @package    mod_forum
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_forum\local\vaults\preprocessors;
+
+defined('MOODLE_INTERNAL') || die();
+
+use moodle_database;
+use core\dml\table as dml_table;
+
+/**
+ * Extract record vault preprocessor.
+ *
+ * Extract record vault preprocessor. Typically used to separate out records
+ * when two tables have been joined together in a query.
+ *
+ * @copyright  2019 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class extract_record {
+    /** @var \core\dml\table $table The table object relating to the table that the records were loaded from */
+    private $table;
+
+    /**
+     * Constructor.
+     *
+     * @param string $table The table name where the records were loaded from
+     * @param string $alias The table alias used as the record property prefix
+     */
+    public function __construct(string $table, string $alias) {
+        $this->table = new dml_table($table, $alias, $alias);
+    }
+
+    /**
+     * Extract a record embedded in the properties of another record out into a
+     * separate record.
+     *
+     * @param stdClass[] $records The list of records to process
+     * @return stdClass[] The extracted records
+     */
+    public function execute(array $records): array {
+        return array_map(function($record) {
+            return $this->table->extract_from_result($record);
+        }, $records);
+    }
+}

mod/forum/classes/local/vaults/preprocessors/extract_user.php

@@ -0,0 +1,71 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Extract user vault preprocessor.
+ *
+ * @package    mod_forum
+ * @copyright  2018 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_forum\local\vaults\preprocessors;
+
+defined('MOODLE_INTERNAL') || die();
+
+use user_picture;
+
+/**
+ * Extract user vault preprocessor.
+ *
+ * Used to separate out the user record
+ * from a list of DB records that have been joined on the user table.
+ *
+ * @copyright  2018 Ryan Wyllie <ryan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class extract_user {
+    /** @var string $idalias The alias for the id property of the user */
+    private $idalias;
+    /** @var string $alias The prefix used for each of the user properties */
+    private $alias;
+
+    /**
+     * Constructor.
+     *
+     * @param string $idalias The alias for the id property of the user
+     * @param string $alias The prefix used for each of the user properties
+     */
+    public function __construct(string $idalias, string $alias) {
+        $this->idalias = $idalias;
+        $this->alias = $alias;
+    }
+
+    /**
+     * Extract the user records from a list of DB records.
+     *
+     * @param stdClass[] $records The DB records
+     * @return stdClass[] The list of extracted users
+     */
+    public function execute(array $records): array {
+        $idalias = $this->idalias;
+        $alias = $this->alias;
+
+        return array_map(function($record) use ($idalias, $alias) {
+            return user_picture::unalias($record, ['deleted'], $idalias, $alias);
+        }, $records);
+    }
+}