first commit

mod/chat/classes/analytics/indicator/activity_base.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/>.
+
+/**
+ * Activity base class.
+ *
+ * @package   mod_chat
+ * @copyright 2017 onwards Ankit Agarwal <ankit.agrr@gmail.com>
+ * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_chat\analytics\indicator;
+
+defined('MOODLE_INTERNAL') || die();
+
+/**
+ * Activity base class.
+ *
+ * @package   mod_chat
+ * @copyright 2017 onwards Ankit Agarwal <ankit.agrr@gmail.com>
+ * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+abstract class activity_base extends \core_analytics\local\indicator\community_of_inquiry_activity {
+
+    /**
+     * feedback_viewed_events
+     *
+     * @return string[]
+     */
+    protected function feedback_viewed_events() {
+        return array('\mod_chat\event\course_module_viewed', '\mod_chat\event\message_sent',
+            '\mod_chat\event\sessions_viewed');
+    }
+
+    /**
+     * feedback_replied_events
+     *
+     * @return string[]
+     */
+    protected function feedback_replied_events() {
+        return array('\mod_chat\event\message_sent');
+    }
+
+    /**
+     * feedback_post_action
+     *
+     * @param \cm_info $cm
+     * @param int $contextid
+     * @param int $userid
+     * @param string[] $eventnames
+     * @param int $after
+     * @return bool
+     */
+    protected function feedback_post_action(\cm_info $cm, $contextid, $userid, $eventnames, $after = false) {
+
+        if (empty($this->activitylogs[$contextid][$userid])) {
+            return false;
+        }
+
+        $logs = $this->activitylogs[$contextid][$userid];
+
+        if (empty($logs['\mod_chat\event\message_sent'])) {
+            // No feedback viewed if there is no submission.
+            return false;
+        }
+
+        // First user message time.
+        $firstmessage = $logs['\mod_chat\event\message_sent']->timecreated[0];
+
+        // We consider feedback another user messages.
+        foreach ($this->activitylogs[$contextid] as $anotheruserid => $logs) {
+            if ($anotheruserid == $userid) {
+                continue;
+            }
+            if (empty($logs['\mod_chat\event\message_sent'])) {
+                continue;
+            }
+            $firstmessagesenttime = $logs['\mod_chat\event\message_sent']->timecreated[0];
+
+            if (parent::feedback_post_action($cm, $contextid, $userid, $eventnames, $firstmessagesenttime)) {
+                return true;
+            }
+            // Continue with the next user.
+        }
+
+        return false;
+    }
+
+    /**
+     * feedback_check_grades
+     *
+     * @return bool
+     */
+    protected function feedback_check_grades() {
+        // Chat's feedback is not contained in grades.
+        return false;
+    }
+}

mod/chat/classes/analytics/indicator/cognitive_depth.php

@@ -0,0 +1,56 @@
+<?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/>.
+
+/**
+ * Cognitive depth indicator - chat.
+ *
+ * @package   mod_chat
+ * @copyright 2017 David Monllao {@link http://www.davidmonllao.com}
+ * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_chat\analytics\indicator;
+
+defined('MOODLE_INTERNAL') || die();
+
+/**
+ * Cognitive depth indicator - chat.
+ *
+ * @package   mod_chat
+ * @copyright 2017 David Monllao {@link http://www.davidmonllao.com}
+ * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class cognitive_depth extends activity_base {
+
+    /**
+     * Returns the name.
+     *
+     * If there is a corresponding '_help' string this will be shown as well.
+     *
+     * @return \lang_string
+     */
+    public static function get_name(): \lang_string {
+        return new \lang_string('indicator:cognitivedepth', 'mod_chat');
+    }
+
+    public function get_indicator_type() {
+        return self::INDICATOR_COGNITIVE;
+    }
+
+    public function get_cognitive_depth_level(\cm_info $cm) {
+        return self::COGNITIVE_LEVEL_4;
+    }
+}

mod/chat/classes/analytics/indicator/social_breadth.php

@@ -0,0 +1,56 @@
+<?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/>.
+
+/**
+ * Social breadth indicator - chat.
+ *
+ * @package   mod_chat
+ * @copyright 2017 David Monllao {@link http://www.davidmonllao.com}
+ * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_chat\analytics\indicator;
+
+defined('MOODLE_INTERNAL') || die();
+
+/**
+ * Social breadth indicator - chat.
+ *
+ * @package   mod_chat
+ * @copyright 2017 David Monllao {@link http://www.davidmonllao.com}
+ * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class social_breadth extends activity_base {
+
+    /**
+     * Returns the name.
+     *
+     * If there is a corresponding '_help' string this will be shown as well.
+     *
+     * @return \lang_string
+     */
+    public static function get_name(): \lang_string {
+        return new \lang_string('indicator:socialbreadth', 'mod_chat');
+    }
+
+    public function get_indicator_type() {
+        return self::INDICATOR_SOCIAL;
+    }
+
+    public function get_social_breadth_level(\cm_info $cm) {
+        return self::SOCIAL_LEVEL_2;
+    }
+}

mod/chat/classes/dates.php

@@ -0,0 +1,58 @@
+<?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/>.
+
+/**
+ * Contains the class for fetching the important dates in mod_chat for a given module instance and a user.
+ *
+ * @package   mod_chat
+ * @copyright 2021 Dongsheng Cai
+ * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+declare(strict_types=1);
+
+namespace mod_chat;
+
+use core\activity_dates;
+
+/**
+ * Class for fetching the important dates in mod_chat for a given module instance and a user.
+ *
+ */
+class dates extends activity_dates {
+    /**
+     * Returns a list of important dates in mod_chat.
+     *
+     * @return array
+     */
+    protected function get_dates(): array {
+        $customdata = $this->cm->customdata;
+        $chat = (object) $customdata;
+        $chattime = $chat->chattime ?? 0;
+        $now = time();
+        if (!empty($chat->schedule) && $chattime > $now) {
+            return [
+                [
+                    'dataid' => 'chattime',
+                    'label'     => get_string('nextchattime', 'mod_chat'),
+                    'timestamp' => (int) $chattime
+                ]
+            ];
+        }
+
+        return [];
+    }
+}

mod/chat/classes/event/course_module_instance_list_viewed.php

@@ -0,0 +1,38 @@
+<?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/>.
+
+/**
+ * The mod_chat instance list viewed event.
+ *
+ * @package    mod_chat
+ * @copyright  2013 onwards Ankit Agarwal
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_chat\event;
+defined('MOODLE_INTERNAL') || die();
+
+/**
+ * The mod_chat instance list viewed event class.
+ *
+ * @package    mod_chat
+ * @since      Moodle 2.7
+ * @copyright  2013 onwards Ankit Agarwal
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class course_module_instance_list_viewed extends \core\event\course_module_instance_list_viewed {
+}
+

mod/chat/classes/event/course_module_viewed.php

@@ -0,0 +1,47 @@
+<?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/>.
+
+/**
+ * The mod_chat course module viewed event.
+ *
+ * @package    mod_chat
+ * @copyright  2014 Petr Skoda
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_chat\event;
+
+defined('MOODLE_INTERNAL') || die();
+
+/**
+ * The mod_chat course module viewed event class.
+ *
+ * @package    mod_chat
+ * @since      Moodle 2.7
+ * @copyright  2014 Petr Skoda
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class course_module_viewed extends \core\event\course_module_viewed {
+    protected function init() {
+        $this->data['crud'] = 'r';
+        $this->data['edulevel'] = self::LEVEL_PARTICIPATING;
+        $this->data['objecttable'] = 'chat';
+    }
+
+    public static function get_objectid_mapping() {
+        return array('db' => 'chat', 'restore' => 'chat');
+    }
+}

mod/chat/classes/event/message_sent.php

@@ -0,0 +1,93 @@
+<?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/>.
+
+/**
+ * The mod_chat message sent event.
+ *
+ * @package    mod_chat
+ * @copyright  2013 Frédéric Massart
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_chat\event;
+defined('MOODLE_INTERNAL') || die();
+
+/**
+ * The mod_chat message sent event class.
+ *
+ * @package    mod_chat
+ * @since      Moodle 2.6
+ * @copyright  2013 Frédéric Massart
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class message_sent extends \core\event\base {
+
+    /**
+     * Returns description of what happened.
+     *
+     * @return string
+     */
+    public function get_description() {
+        return "The user with id '$this->relateduserid' has sent a message in the chat with course module id
+            '$this->contextinstanceid'.";
+    }
+
+    /**
+     * Return localised event name.
+     *
+     * @return string
+     */
+    public static function get_name() {
+        return get_string('eventmessagesent', 'mod_chat');
+    }
+
+    /**
+     * Get URL related to the action
+     *
+     * @return \moodle_url
+     */
+    public function get_url() {
+        return new \moodle_url('/mod/chat/view.php', array('id' => $this->contextinstanceid));
+    }
+
+    /**
+     * Init method.
+     *
+     * @return void
+     */
+    protected function init() {
+        $this->data['crud'] = 'c';
+        $this->data['edulevel'] = self::LEVEL_PARTICIPATING;
+        $this->data['objecttable'] = 'chat_messages';
+    }
+
+    /**
+     * Custom validation.
+     *
+     * @throws \coding_exception
+     * @return void
+     */
+    protected function validate_data() {
+        parent::validate_data();
+        if (!isset($this->relateduserid)) {
+            throw new \coding_exception('The \'relateduserid\' must be set.');
+        }
+    }
+
+    public static function get_objectid_mapping() {
+        return array('db' => 'chat_messages', 'restore' => 'chat_message');
+    }
+}

mod/chat/classes/event/sessions_viewed.php

@@ -0,0 +1,108 @@
+<?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/>.
+
+/**
+ * The mod_chat sessions viewed event.
+ *
+ * @package    mod_chat
+ * @copyright  2013 Frédéric Massart
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_chat\event;
+defined('MOODLE_INTERNAL') || die();
+
+/**
+ * The mod_chat sessions viewed event class.
+ *
+ * @property-read array $other {
+ *      Extra information about the event.
+ *
+ *      - int start: start of period.
+ *      - int end: end of period.
+ * }
+ *
+ * @package    mod_chat
+ * @since      Moodle 2.6
+ * @copyright  2013 Frédéric Massart
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class sessions_viewed extends \core\event\base {
+
+    /**
+     * Returns description of what happened.
+     *
+     * @return string
+     */
+    public function get_description() {
+        return "The user with id '$this->userid' has viewed the sessions of the chat with course module id
+            '$this->contextinstanceid'.";
+    }
+
+    /**
+     * Return localised event name.
+     *
+     * @return string
+     */
+    public static function get_name() {
+        return get_string('eventsessionsviewed', 'mod_chat');
+    }
+
+    /**
+     * Get URL related to the action
+     *
+     * @return \moodle_url
+     */
+    public function get_url() {
+        return new \moodle_url('/mod/chat/report.php', array('id' => $this->contextinstanceid));
+    }
+
+    /**
+     * Init method.
+     *
+     * @return void
+     */
+    protected function init() {
+        $this->data['crud'] = 'r';
+        $this->data['edulevel'] = self::LEVEL_OTHER;
+        $this->data['objecttable'] = 'chat';
+    }
+
+    /**
+     * Custom validation.
+     *
+     * @throws \coding_exception
+     * @return void
+     */
+    protected function validate_data() {
+        parent::validate_data();
+        if (!isset($this->other['start'])) {
+            throw new \coding_exception('The \'start\' value must be set in other.');
+        }
+        if (!isset($this->other['end'])) {
+            throw new \coding_exception('The \'end\' value must be set in other.');
+        }
+    }
+
+    public static function get_objectid_mapping() {
+        return array('db' => 'chat', 'restore' => 'chat');
+    }
+
+    public static function get_other_mapping() {
+        // Nothing to map.
+        return false;
+    }
+}

mod/chat/classes/external.php

@@ -0,0 +1,833 @@
+<?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/>.
+
+/**
+ * Chat external API
+ *
+ * @package    mod_chat
+ * @category   external
+ * @copyright  2015 Juan Leyva <juan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ * @since      Moodle 3.0
+ */
+
+defined('MOODLE_INTERNAL') || die;
+
+require_once($CFG->dirroot . '/mod/chat/lib.php');
+
+use core_course\external\helper_for_get_mods_by_courses;
+use core_external\external_api;
+use core_external\external_function_parameters;
+use core_external\external_multiple_structure;
+use core_external\external_single_structure;
+use core_external\external_value;
+use core_external\external_warnings;
+use core_external\util;
+use mod_chat\external\chat_message_exporter;
+
+/**
+ * Chat external functions
+ *
+ * @package    mod_chat
+ * @category   external
+ * @copyright  2015 Juan Leyva <juan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ * @since      Moodle 3.0
+ */
+class mod_chat_external extends external_api {
+
+    /**
+     * Returns description of method parameters
+     *
+     * @return external_function_parameters
+     * @since Moodle 3.0
+     */
+    public static function login_user_parameters() {
+        return new external_function_parameters(
+            array(
+                'chatid' => new external_value(PARAM_INT, 'chat instance id'),
+                'groupid' => new external_value(PARAM_INT, 'group id, 0 means that the function will determine the user group',
+                                                VALUE_DEFAULT, 0),
+            )
+        );
+    }
+
+    /**
+     * Log the current user into a chat room in the given chat.
+     *
+     * @param int $chatid the chat instance id
+     * @param int $groupid the user group id
+     * @return array of warnings and the chat unique session id
+     * @since Moodle 3.0
+     * @throws moodle_exception
+     */
+    public static function login_user($chatid, $groupid = 0) {
+        global $DB;
+
+        $params = self::validate_parameters(self::login_user_parameters(),
+                                            array(
+                                                'chatid' => $chatid,
+                                                'groupid' => $groupid
+                                            ));
+        $warnings = array();
+
+        // Request and permission validation.
+        $chat = $DB->get_record('chat', array('id' => $params['chatid']), '*', MUST_EXIST);
+        list($course, $cm) = get_course_and_cm_from_instance($chat, 'chat');
+
+        $context = context_module::instance($cm->id);
+        self::validate_context($context);
+
+        require_capability('mod/chat:chat', $context);
+
+        if (!empty($params['groupid'])) {
+            $groupid = $params['groupid'];
+            // Determine is the group is visible to user.
+            if (!groups_group_visible($groupid, $course, $cm)) {
+                throw new moodle_exception('notingroup');
+            }
+        } else {
+            // Check to see if groups are being used here.
+            if ($groupmode = groups_get_activity_groupmode($cm)) {
+                $groupid = groups_get_activity_group($cm);
+                // Determine is the group is visible to user (this is particullary for the group 0).
+                if (!groups_group_visible($groupid, $course, $cm)) {
+                    throw new moodle_exception('notingroup');
+                }
+            } else {
+                $groupid = 0;
+            }
+        }
+
+        // Get the unique chat session id.
+        // Since we are going to use the chat via Web Service requests we set the ajax version (since it's the most similar).
+        if (!$chatsid = chat_login_user($chat->id, 'ajax', $groupid, $course)) {
+            throw new moodle_exception('cantlogin', 'chat');
+        }
+
+        $result = array();
+        $result['chatsid'] = $chatsid;
+        $result['warnings'] = $warnings;
+        return $result;
+    }
+
+    /**
+     * Returns description of method result value
+     *
+     * @return \core_external\external_description
+     * @since Moodle 3.0
+     */
+    public static function login_user_returns() {
+        return new external_single_structure(
+            array(
+                'chatsid' => new external_value(PARAM_ALPHANUM, 'unique chat session id'),
+                'warnings' => new external_warnings()
+            )
+        );
+    }
+
+    /**
+     * Returns description of method parameters
+     *
+     * @return external_function_parameters
+     * @since Moodle 3.0
+     */
+    public static function get_chat_users_parameters() {
+        return new external_function_parameters(
+            array(
+                'chatsid' => new external_value(PARAM_ALPHANUM, 'chat session id (obtained via mod_chat_login_user)')
+            )
+        );
+    }
+
+    /**
+     * Get the list of users in the given chat session.
+     *
+     * @param int $chatsid the chat session id
+     * @return array of warnings and the user lists
+     * @since Moodle 3.0
+     * @throws moodle_exception
+     */
+    public static function get_chat_users($chatsid) {
+        global $DB, $PAGE;
+
+        $params = self::validate_parameters(self::get_chat_users_parameters(),
+                                            array(
+                                                'chatsid' => $chatsid
+                                            ));
+        $warnings = array();
+
+        // Request and permission validation.
+        if (!$chatuser = $DB->get_record('chat_users', array('sid' => $params['chatsid']))) {
+            throw new moodle_exception('notlogged', 'chat');
+        }
+        $chat = $DB->get_record('chat', array('id' => $chatuser->chatid), '*', MUST_EXIST);
+        list($course, $cm) = get_course_and_cm_from_instance($chat, 'chat');
+
+        $context = context_module::instance($cm->id);
+        self::validate_context($context);
+
+        require_capability('mod/chat:chat', $context);
+
+        // First, delete old users from the chats.
+        chat_delete_old_users();
+
+        $users = chat_get_users($chatuser->chatid, $chatuser->groupid, $cm->groupingid);
+        $returnedusers = array();
+
+        foreach ($users as $user) {
+
+            $userpicture = new user_picture($user);
+            $userpicture->size = 1; // Size f1.
+            $profileimageurl = $userpicture->get_url($PAGE)->out(false);
+
+            $returnedusers[] = array(
+                'id' => $user->id,
+                'fullname' => fullname($user),
+                'profileimageurl' => $profileimageurl
+            );
+        }
+
+        $result = array();
+        $result['users'] = $returnedusers;
+        $result['warnings'] = $warnings;
+        return $result;
+    }
+
+    /**
+     * Returns description of method result value
+     *
+     * @return \core_external\external_description
+     * @since Moodle 3.0
+     */
+    public static function get_chat_users_returns() {
+        return new external_single_structure(
+            array(
+                'users' => new external_multiple_structure(
+                    new external_single_structure(
+                        array(
+                            'id' => new external_value(PARAM_INT, 'user id'),
+                            'fullname' => new external_value(PARAM_NOTAGS, 'user full name'),
+                            'profileimageurl' => new external_value(PARAM_URL, 'user picture URL'),
+                        )
+                    ),
+                    'list of users'
+                ),
+                'warnings' => new external_warnings()
+            )
+        );
+    }
+
+    /**
+     * Returns description of method parameters
+     *
+     * @return external_function_parameters
+     * @since Moodle 3.0
+     */
+    public static function send_chat_message_parameters() {
+        return new external_function_parameters(
+            array(
+                'chatsid' => new external_value(PARAM_ALPHANUM, 'chat session id (obtained via mod_chat_login_user)'),
+                'messagetext' => new external_value(PARAM_RAW, 'the message text'),
+                'beepid' => new external_value(PARAM_RAW, 'the beep id', VALUE_DEFAULT, ''),
+
+            )
+        );
+    }
+
+    /**
+     * Send a message on the given chat session.
+     *
+     * @param int $chatsid the chat session id
+     * @param string $messagetext the message text
+     * @param string $beepid the beep message id
+     * @return array of warnings and the new message id (0 if the message was empty)
+     * @since Moodle 3.0
+     * @throws moodle_exception
+     */
+    public static function send_chat_message($chatsid, $messagetext, $beepid = '') {
+        global $DB;
+
+        $params = self::validate_parameters(self::send_chat_message_parameters(),
+                                            array(
+                                                'chatsid' => $chatsid,
+                                                'messagetext' => $messagetext,
+                                                'beepid' => $beepid
+                                            ));
+        $warnings = array();
+
+        // Request and permission validation.
+        if (!$chatuser = $DB->get_record('chat_users', array('sid' => $params['chatsid']))) {
+            throw new moodle_exception('notlogged', 'chat');
+        }
+        $chat = $DB->get_record('chat', array('id' => $chatuser->chatid), '*', MUST_EXIST);
+        list($course, $cm) = get_course_and_cm_from_instance($chat, 'chat');
+
+        $context = context_module::instance($cm->id);
+        self::validate_context($context);
+
+        require_capability('mod/chat:chat', $context);
+
+        $chatmessage = clean_text($params['messagetext'], FORMAT_MOODLE);
+
+        if (!empty($params['beepid'])) {
+            $chatmessage = 'beep ' . $params['beepid'];
+        }
+
+        if (!empty($chatmessage)) {
+            // Send the message.
+            $messageid = chat_send_chatmessage($chatuser, $chatmessage, 0, $cm);
+            // Update ping time.
+            $chatuser->lastmessageping = time() - 2;
+            $DB->update_record('chat_users', $chatuser);
+        } else {
+            $messageid = 0;
+        }
+
+        $result = array();
+        $result['messageid'] = $messageid;
+        $result['warnings'] = $warnings;
+        return $result;
+    }
+
+    /**
+     * Returns description of method result value
+     *
+     * @return \core_external\external_description
+     * @since Moodle 3.0
+     */
+    public static function send_chat_message_returns() {
+        return new external_single_structure(
+            array(
+                'messageid' => new external_value(PARAM_INT, 'message sent id'),
+                'warnings' => new external_warnings()
+            )
+        );
+    }
+
+    /**
+     * Returns description of method parameters
+     *
+     * @return external_function_parameters
+     * @since Moodle 3.0
+     */
+    public static function get_chat_latest_messages_parameters() {
+        return new external_function_parameters(
+            array(
+                'chatsid' => new external_value(PARAM_ALPHANUM, 'chat session id (obtained via mod_chat_login_user)'),
+                'chatlasttime' => new external_value(PARAM_INT, 'last time messages were retrieved (epoch time)', VALUE_DEFAULT, 0)
+            )
+        );
+    }
+
+    /**
+     * Get the latest messages from the given chat session.
+     *
+     * @param int $chatsid the chat session id
+     * @param int $chatlasttime last time messages were retrieved (epoch time)
+     * @return array of warnings and the new message id (0 if the message was empty)
+     * @since Moodle 3.0
+     * @throws moodle_exception
+     */
+    public static function get_chat_latest_messages($chatsid, $chatlasttime = 0) {
+        global $DB, $CFG;
+
+        $params = self::validate_parameters(self::get_chat_latest_messages_parameters(),
+                                            array(
+                                                'chatsid' => $chatsid,
+                                                'chatlasttime' => $chatlasttime
+                                            ));
+        $warnings = array();
+
+        // Request and permission validation.
+        if (!$chatuser = $DB->get_record('chat_users', array('sid' => $params['chatsid']))) {
+            throw new moodle_exception('notlogged', 'chat');
+        }
+        $chat = $DB->get_record('chat', array('id' => $chatuser->chatid), '*', MUST_EXIST);
+        list($course, $cm) = get_course_and_cm_from_instance($chat, 'chat');
+
+        $context = context_module::instance($cm->id);
+        self::validate_context($context);
+
+        require_capability('mod/chat:chat', $context);
+
+        $chatlasttime = $params['chatlasttime'];
+        if ((time() - $chatlasttime) > $CFG->chat_old_ping) {
+            chat_delete_old_users();
+        }
+
+        // Set default chat last time (to not retrieve all the conversations).
+        if ($chatlasttime == 0) {
+            $chatlasttime = time() - $CFG->chat_old_ping;
+        }
+
+        if ($latestmessage = chat_get_latest_message($chatuser->chatid, $chatuser->groupid)) {
+            $chatnewlasttime = $latestmessage->timestamp;
+        } else {
+            $chatnewlasttime = 0;
+        }
+
+        $messages = chat_get_latest_messages($chatuser, $chatlasttime);
+        $returnedmessages = array();
+
+        foreach ($messages as $message) {
+            // FORMAT_MOODLE is mandatory in the chat plugin.
+            [$messageformatted] = \core_external\util::format_text(
+                $message->message,
+                FORMAT_MOODLE,
+                $context->id,
+                'mod_chat',
+                '',
+                0
+            );
+
+            $returnedmessages[] = array(
+                'id' => $message->id,
+                'userid' => $message->userid,
+                'system' => (bool) $message->issystem,
+                'message' => $messageformatted,
+                'timestamp' => $message->timestamp,
+            );
+        }
+
+        // Update our status since we are active in the chat.
+        $DB->set_field('chat_users', 'lastping', time(), array('id' => $chatuser->id));
+
+        $result = array();
+        $result['messages'] = $returnedmessages;
+        $result['chatnewlasttime'] = $chatnewlasttime;
+        $result['warnings'] = $warnings;
+        return $result;
+    }
+
+    /**
+     * Returns description of method result value
+     *
+     * @return \core_external\external_description
+     * @since Moodle 3.0
+     */
+    public static function get_chat_latest_messages_returns() {
+        return new external_single_structure(
+            array(
+                'messages' => new external_multiple_structure(
+                    new external_single_structure(
+                        array(
+                            'id' => new external_value(PARAM_INT, 'message id'),
+                            'userid' => new external_value(PARAM_INT, 'user id'),
+                            'system' => new external_value(PARAM_BOOL, 'true if is a system message (like user joined)'),
+                            'message' => new external_value(PARAM_RAW, 'message text'),
+                            'timestamp' => new external_value(PARAM_INT, 'timestamp for the message'),
+                        )
+                    ),
+                    'list of users'
+                ),
+                'chatnewlasttime' => new external_value(PARAM_INT, 'new last time'),
+                'warnings' => new external_warnings()
+            )
+        );
+    }
+
+    /**
+     * Returns description of method parameters
+     *
+     * @return external_function_parameters
+     * @since Moodle 3.0
+     */
+    public static function view_chat_parameters() {
+        return new external_function_parameters(
+            array(
+                'chatid' => new external_value(PARAM_INT, 'chat instance id')
+            )
+        );
+    }
+
+    /**
+     * Trigger the course module viewed event and update the module completion status.
+     *
+     * @param int $chatid the chat instance id
+     * @return array of warnings and status result
+     * @since Moodle 3.0
+     * @throws moodle_exception
+     */
+    public static function view_chat($chatid) {
+        global $DB, $CFG;
+
+        $params = self::validate_parameters(self::view_chat_parameters(),
+                                            array(
+                                                'chatid' => $chatid
+                                            ));
+        $warnings = array();
+
+        // Request and permission validation.
+        $chat = $DB->get_record('chat', array('id' => $params['chatid']), '*', MUST_EXIST);
+        list($course, $cm) = get_course_and_cm_from_instance($chat, 'chat');
+
+        $context = context_module::instance($cm->id);
+        self::validate_context($context);
+
+        require_capability('mod/chat:chat', $context);
+
+        // Call the url/lib API.
+        chat_view($chat, $course, $cm, $context);
+
+        $result = array();
+        $result['status'] = true;
+        $result['warnings'] = $warnings;
+        return $result;
+    }
+
+    /**
+     * Returns description of method result value
+     *
+     * @return \core_external\external_description
+     * @since Moodle 3.0
+     */
+    public static function view_chat_returns() {
+        return new external_single_structure(
+            array(
+                'status' => new external_value(PARAM_BOOL, 'status: true if success'),
+                'warnings' => new external_warnings()
+            )
+        );
+    }
+
+
+    /**
+     * Describes the parameters for get_chats_by_courses.
+     *
+     * @return external_function_parameters
+     * @since Moodle 3.0
+     */
+    public static function get_chats_by_courses_parameters() {
+        return new external_function_parameters (
+            array(
+                'courseids' => new external_multiple_structure(
+                    new external_value(PARAM_INT, 'course id'), 'Array of course ids', VALUE_DEFAULT, array()
+                ),
+            )
+        );
+    }
+
+    /**
+     * Returns a list of chats in a provided list of courses,
+     * if no list is provided all chats that the user can view will be returned.
+     *
+     * @param array $courseids the course ids
+     * @return array of chats details
+     * @since Moodle 3.0
+     */
+    public static function get_chats_by_courses($courseids = array()) {
+        global $CFG;
+
+        $returnedchats = array();
+        $warnings = array();
+
+        $params = self::validate_parameters(self::get_chats_by_courses_parameters(), array('courseids' => $courseids));
+
+        $courses = array();
+        if (empty($params['courseids'])) {
+            $courses = enrol_get_my_courses();
+            $params['courseids'] = array_keys($courses);
+        }
+
+        // Ensure there are courseids to loop through.
+        if (!empty($params['courseids'])) {
+
+            list($courses, $warnings) = util::validate_courses($params['courseids'], $courses);
+
+            // Get the chats in this course, this function checks users visibility permissions.
+            // We can avoid then additional validate_context calls.
+            $chats = get_all_instances_in_courses("chat", $courses);
+            foreach ($chats as $chat) {
+                $chatcontext = context_module::instance($chat->coursemodule);
+
+                $chatdetails = helper_for_get_mods_by_courses::standard_coursemodule_element_values($chat, 'mod_chat');
+
+                if (has_capability('mod/chat:chat', $chatcontext)) {
+                    $chatdetails['chatmethod']    = $CFG->chat_method;
+                    $chatdetails['keepdays']      = $chat->keepdays;
+                    $chatdetails['studentlogs']   = $chat->studentlogs;
+                    $chatdetails['chattime']      = $chat->chattime;
+                    $chatdetails['schedule']      = $chat->schedule;
+                }
+
+                if (has_capability('moodle/course:manageactivities', $chatcontext)) {
+                    $chatdetails['timemodified']  = $chat->timemodified;
+                }
+                $returnedchats[] = $chatdetails;
+            }
+        }
+        $result = array();
+        $result['chats'] = $returnedchats;
+        $result['warnings'] = $warnings;
+        return $result;
+    }
+
+    /**
+     * Describes the get_chats_by_courses return value.
+     *
+     * @return external_single_structure
+     * @since Moodle 3.0
+     */
+    public static function get_chats_by_courses_returns() {
+        return new external_single_structure(
+            array(
+                'chats' => new external_multiple_structure(
+                    new external_single_structure(array_merge(
+                        helper_for_get_mods_by_courses::standard_coursemodule_elements_returns(),
+                        [
+                            'chatmethod' => new external_value(PARAM_PLUGIN, 'chat method (sockets, ajax, header_js)',
+                                VALUE_OPTIONAL),
+                            'keepdays' => new external_value(PARAM_INT, 'keep days', VALUE_OPTIONAL),
+                            'studentlogs' => new external_value(PARAM_INT, 'student logs visible to everyone', VALUE_OPTIONAL),
+                            'chattime' => new external_value(PARAM_INT, 'chat time', VALUE_OPTIONAL),
+                            'schedule' => new external_value(PARAM_INT, 'schedule type', VALUE_OPTIONAL),
+                            'timemodified' => new external_value(PARAM_INT, 'time of last modification', VALUE_OPTIONAL),
+                        ]
+                    ), 'Chats')
+                ),
+                'warnings' => new external_warnings(),
+            )
+        );
+    }
+
+    /**
+     * Returns description of method parameters
+     *
+     * @return external_function_parameters
+     * @since Moodle 3.4
+     */
+    public static function get_sessions_parameters() {
+        return new external_function_parameters(
+            array(
+                'chatid' => new external_value(PARAM_INT, 'Chat instance id.'),
+                'groupid' => new external_value(PARAM_INT, 'Get messages from users in this group.
+                                                0 means that the function will determine the user group', VALUE_DEFAULT, 0),
+                'showall' => new external_value(PARAM_BOOL, 'Whether to show completed sessions or not.', VALUE_DEFAULT, false),
+            )
+        );
+    }
+
+    /**
+     * Retrieves chat sessions for a given chat.
+     *
+     * @param int $chatid the chat instance id
+     * @param int $groupid filter messages by this group. 0 to determine the group.
+     * @param bool $showall whether to include incomplete sessions or not
+     * @return array of warnings and the sessions
+     * @since Moodle 3.4
+     * @throws moodle_exception
+     */
+    public static function get_sessions($chatid, $groupid = 0, $showall = false) {
+        global $DB;
+
+        $params = self::validate_parameters(self::get_sessions_parameters(),
+                                            array(
+                                                'chatid' => $chatid,
+                                                'groupid' => $groupid,
+                                                'showall' => $showall,
+                                            ));
+        $sessions = $warnings = array();
+
+        // Request and permission validation.
+        $chat = $DB->get_record('chat', array('id' => $params['chatid']), '*', MUST_EXIST);
+        list($course, $cm) = get_course_and_cm_from_instance($chat, 'chat');
+
+        $context = context_module::instance($cm->id);
+        self::validate_context($context);
+
+        if (empty($chat->studentlogs) && !has_capability('mod/chat:readlog', $context)) {
+            throw new moodle_exception('nopermissiontoseethechatlog', 'chat');
+        }
+
+        if (!empty($params['groupid'])) {
+            $groupid = $params['groupid'];
+            // Determine is the group is visible to user.
+            if (!groups_group_visible($groupid, $course, $cm)) {
+                throw new moodle_exception('notingroup');
+            }
+        } else {
+            // Check to see if groups are being used here.
+            if ($groupmode = groups_get_activity_groupmode($cm)) {
+                $groupid = groups_get_activity_group($cm);
+                // Determine is the group is visible to user (this is particullary for the group 0).
+                if (!groups_group_visible($groupid, $course, $cm)) {
+                    throw new moodle_exception('notingroup');
+                }
+            } else {
+                $groupid = 0;
+            }
+        }
+
+        $messages = chat_get_session_messages($chat->id, $groupid, 0, 0, 'timestamp DESC');
+        if ($messages) {
+            $chatsessions = chat_get_sessions($messages, $params['showall']);
+            // Format sessions for external.
+            foreach ($chatsessions as $session) {
+                $sessionusers = array();
+                foreach ($session->sessionusers as $sessionuser => $usermessagecount) {
+                    $sessionusers[] = array(
+                        'userid' => $sessionuser,
+                        'messagecount' => $usermessagecount
+                    );
+                }
+                $session->sessionusers = $sessionusers;
+                $sessions[] = $session;
+            }
+        }
+
+        $result = array();
+        $result['sessions'] = $sessions;
+        $result['warnings'] = $warnings;
+        return $result;
+    }
+
+    /**
+     * Returns description of method result value
+     *
+     * @return \core_external\external_description
+     * @since Moodle 3.4
+     */
+    public static function get_sessions_returns() {
+        return new external_single_structure(
+            array(
+                'sessions' => new external_multiple_structure(
+                    new external_single_structure(
+                        array(
+                            'sessionstart' => new external_value(PARAM_INT, 'Session start time.'),
+                            'sessionend' => new external_value(PARAM_INT, 'Session end time.'),
+                            'sessionusers' => new external_multiple_structure(
+                                new external_single_structure(
+                                    array(
+                                        'userid' => new external_value(PARAM_INT, 'User id.'),
+                                        'messagecount' => new external_value(PARAM_INT, 'Number of messages in the session.'),
+                                    )
+                                ), 'Session users.'
+                            ),
+                            'iscomplete' => new external_value(PARAM_BOOL, 'Whether the session is completed or not.'),
+                        )
+                    ),
+                    'list of users'
+                ),
+                'warnings' => new external_warnings()
+            )
+        );
+    }
+
+    /**
+     * Returns description of method parameters
+     *
+     * @return external_function_parameters
+     * @since Moodle 3.4
+     */
+    public static function get_session_messages_parameters() {
+        return new external_function_parameters(
+            array(
+                'chatid' => new external_value(PARAM_INT, 'Chat instance id.'),
+                'sessionstart' => new external_value(PARAM_INT, 'The session start time (timestamp).'),
+                'sessionend' => new external_value(PARAM_INT, 'The session end time (timestamp).'),
+                'groupid' => new external_value(PARAM_INT, 'Get messages from users in this group.
+                                                0 means that the function will determine the user group', VALUE_DEFAULT, 0),
+            )
+        );
+    }
+
+    /**
+     * Retrieves messages of the given chat session.
+     *
+     * @param int $chatid the chat instance id
+     * @param int $sessionstart the session start time (timestamp)
+     * @param int $sessionend the session end time (timestamp)
+     * @param int $groupid filter messages by this group. 0 to determine the group.
+     * @return array of warnings and the messages
+     * @since Moodle 3.4
+     * @throws moodle_exception
+     */
+    public static function get_session_messages($chatid, $sessionstart, $sessionend, $groupid = 0) {
+        global $DB, $PAGE;
+
+        $params = self::validate_parameters(self::get_session_messages_parameters(),
+                                            array(
+                                                'chatid' => $chatid,
+                                                'sessionstart' => $sessionstart,
+                                                'sessionend' => $sessionend,
+                                                'groupid' => $groupid,
+                                            ));
+        $messages = $warnings = array();
+
+        // Request and permission validation.
+        $chat = $DB->get_record('chat', array('id' => $params['chatid']), '*', MUST_EXIST);
+        list($course, $cm) = get_course_and_cm_from_instance($chat, 'chat');
+
+        $context = context_module::instance($cm->id);
+        self::validate_context($context);
+
+        if (empty($chat->studentlogs) && !has_capability('mod/chat:readlog', $context)) {
+            throw new moodle_exception('nopermissiontoseethechatlog', 'chat');
+        }
+
+        if (!empty($params['groupid'])) {
+            $groupid = $params['groupid'];
+            // Determine is the group is visible to user.
+            if (!groups_group_visible($groupid, $course, $cm)) {
+                throw new moodle_exception('notingroup');
+            }
+        } else {
+            // Check to see if groups are being used here.
+            if ($groupmode = groups_get_activity_groupmode($cm)) {
+                $groupid = groups_get_activity_group($cm);
+                // Determine is the group is visible to user (this is particullary for the group 0).
+                if (!groups_group_visible($groupid, $course, $cm)) {
+                    throw new moodle_exception('notingroup');
+                }
+            } else {
+                $groupid = 0;
+            }
+        }
+
+        $messages = chat_get_session_messages($chat->id, $groupid, $params['sessionstart'], $params['sessionend'],
+            'timestamp ASC');
+        if ($messages) {
+            foreach ($messages as $message) {
+                $exporter = new chat_message_exporter($message, array('context' => $context));
+                $returneditems[] = $exporter->export($PAGE->get_renderer('core'));
+            }
+        }
+
+        $result = array(
+            'messages' => $messages,
+            'warnings' => $warnings,
+        );
+        return $result;
+    }
+
+    /**
+     * Returns description of method result value
+     *
+     * @return \core_external\external_description
+     * @since Moodle 3.4
+     */
+    public static function get_session_messages_returns() {
+        return new external_single_structure(
+            array(
+                'messages' => new external_multiple_structure(
+                    chat_message_exporter::get_read_structure()
+                ),
+                'warnings' => new external_warnings()
+            )
+        );
+    }
+}

mod/chat/classes/external/chat_message_exporter.php

@@ -0,0 +1,101 @@
+<?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 for exporting a chat message.
+ *
+ * @package    mod_chat
+ * @copyright  2017 Juan Leyva <juan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+namespace mod_chat\external;
+defined('MOODLE_INTERNAL') || die();
+
+use core\external\exporter;
+
+/**
+ * Class for exporting a chat message.
+ *
+ * @copyright  2017 Juan Leyva <juan@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class chat_message_exporter extends exporter {
+
+    /**
+     * Defines exporter properties.
+     *
+     * @return array
+     */
+    protected static function define_properties() {
+        return array(
+            'id' => array(
+                'type' => PARAM_INT,
+                'description' => 'The message record id.',
+            ),
+            'chatid' => array(
+                'type' => PARAM_INT,
+                'description' => 'The chat id.',
+                'default' => 0,
+            ),
+            'userid' => array(
+                'type' => PARAM_INT,
+                'description' => 'The user who wrote the message.',
+                'default' => 0,
+            ),
+            'groupid' => array(
+                'type' => PARAM_INT,
+                'description' => 'The group this message belongs to.',
+                'default' => 0,
+            ),
+            'issystem' => array(
+                'type' => PARAM_BOOL,
+                'description' => 'Whether is a system message or not.',
+                'default' => false,
+            ),
+            'message' => array(
+                'type' => PARAM_RAW,
+                'description' => 'The message text.',
+            ),
+            'timestamp' => array(
+                'type' => PARAM_INT,
+                'description' => 'The message timestamp (indicates when the message was sent).',
+                'default' => 0,
+            ),
+        );
+    }
+
+    /**
+     * Defines related information.
+     *
+     * @return array
+     */
+    protected static function define_related() {
+        return array(
+            'context' => 'context',
+        );
+    }
+
+    /**
+     * Get the formatting parameters for the name.
+     *
+     * @return array
+     */
+    protected function get_format_parameters_for_message() {
+        return [
+            'component' => 'mod_chat',
+        ];
+    }
+}

mod/chat/classes/external/view_sessions.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/>.
+
+namespace mod_chat\external;
+
+use core_external\external_api;
+use core_external\external_function_parameters;
+use core_external\external_single_structure;
+use core_external\external_value;
+use core_external\external_warnings;
+
+/**
+ * External service to log viewed previous chat sessions.
+ *
+ * @package   mod_chat
+ * @category  external
+ * @copyright 2023 Rodrigo Mady <rodrigo.mady@moodle.com>
+ * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ * @since     Moodle 4.3
+ */
+class view_sessions extends external_api {
+    /**
+     * Returns description of method parameters
+     *
+     * @return external_function_parameters
+     */
+    public static function execute_parameters(): external_function_parameters {
+        return new external_function_parameters([
+            'cmid'   => new external_value(PARAM_INT, 'Course module id', VALUE_REQUIRED),
+            'start'  => new external_value(PARAM_INT, 'Session start time', VALUE_DEFAULT, 0),
+            'end'    => new external_value(PARAM_INT, 'Session end time', VALUE_DEFAULT, 0),
+        ]);
+    }
+
+    /**
+     * Execute the chat view sessions event.
+     *
+     * @param int $cmid the chat course module id
+     * @param null|int $start
+     * @param null|int $end
+     * @return array
+     * @throws \restricted_context_exception
+     */
+    public static function execute(int $cmid, ?int $start = 0, ?int $end = 0): array {
+        global $DB;
+        $warnings = [];
+        $status   = false;
+        // Validate the cmid ID.
+        [
+            'cmid'  => $cmid,
+            'start' => $start,
+            'end'   => $end,
+        ] = self::validate_parameters(self::execute_parameters(), [
+            'cmid'  => $cmid,
+            'start' => $start,
+            'end'   => $end,
+        ]);
+        if (!$cm = get_coursemodule_from_id('chat', $cmid)) {
+            throw new \moodle_exception('invalidcoursemodule', 'error');
+        }
+        if (!$chat = $DB->get_record('chat', ['id' => $cm->instance])) {
+            throw new \moodle_exception('invalidcoursemodule', 'error');
+        }
+
+        $context = \context_module::instance($cm->id);
+        self::validate_context($context);
+
+        // Check capability.
+        if (has_capability('mod/chat:readlog', $context)) {
+            $params = [
+                'context'  => $context,
+                'objectid' => $chat->id,
+                'other'    => [
+                    'start' => $start,
+                    'end'   => $end
+                ]
+            ];
+            $event  = \mod_chat\event\sessions_viewed::create($params);
+            $status = true;
+            $event->add_record_snapshot('chat', $chat);
+            $event->trigger();
+        } else {
+            $warnings[] = [
+                'item'        => $cm->id,
+                'warningcode' => 'nopermissiontoseethechatlog',
+                'message'     => get_string('nopermissiontoseethechatlog', 'chat')
+            ];
+        }
+
+        $result = [
+            'status'   => $status,
+            'warnings' => $warnings
+        ];
+        return $result;
+    }
+
+    /**
+     * Describe the return structure of the external service.
+     *
+     * @return external_single_structure
+     */
+    public static function execute_returns(): external_single_structure {
+        return new external_single_structure([
+            'status'   => new external_value(PARAM_BOOL, 'status: true if success'),
+            'warnings' => new external_warnings()
+        ]);
+    }
+}

mod/chat/classes/privacy/provider.php

@@ -0,0 +1,333 @@
+<?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/>.
+
+/**
+ * Data provider.
+ *
+ * @package    mod_chat
+ * @copyright  2018 Frédéric Massart
+ * @author     Frédéric Massart <fred@branchup.tech>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_chat\privacy;
+defined('MOODLE_INTERNAL') || die();
+
+use context;
+use context_helper;
+use context_module;
+use moodle_recordset;
+use stdClass;
+use core_privacy\local\metadata\collection;
+use core_privacy\local\request\approved_contextlist;
+use core_privacy\local\request\approved_userlist;
+use core_privacy\local\request\contextlist;
+use core_privacy\local\request\helper;
+use core_privacy\local\request\transform;
+use core_privacy\local\request\userlist;
+use core_privacy\local\request\writer;
+
+/**
+ * Data provider class.
+ *
+ * @package    mod_chat
+ * @copyright  2018 Frédéric Massart
+ * @author     Frédéric Massart <fred@branchup.tech>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class provider implements
+    \core_privacy\local\metadata\provider,
+    \core_privacy\local\request\core_userlist_provider,
+    \core_privacy\local\request\plugin\provider {
+
+    /**
+     * Returns metadata.
+     *
+     * @param collection $collection The initialised collection to add items to.
+     * @return collection A listing of user data stored through this system.
+     */
+    public static function get_metadata(collection $collection): collection {
+
+        $collection->add_database_table('chat_messages', [
+            'userid' => 'privacy:metadata:messages:userid',
+            'message' => 'privacy:metadata:messages:message',
+            'issystem' => 'privacy:metadata:messages:issystem',
+            'timestamp' => 'privacy:metadata:messages:timestamp',
+        ], 'privacy:metadata:messages');
+
+        // The tables chat_messages_current and chat_users are not exported/deleted
+        // because they are considered as short-lived data and are deleted on a
+        // regular basis by cron, or during normal requests. TODO MDL-62006.
+
+        $collection->add_database_table('chat_messages_current', [
+            'userid' => 'privacy:metadata:messages:userid',
+            'message' => 'privacy:metadata:messages:message',
+            'issystem' => 'privacy:metadata:messages:issystem',
+            'timestamp' => 'privacy:metadata:messages:timestamp'
+        ], 'privacy:metadata:chat_messages_current');
+
+        $collection->add_database_table('chat_users', [
+            'userid' => 'privacy:metadata:chat_users:userid',
+            'version' => 'privacy:metadata:chat_users:version',
+            'ip' => 'privacy:metadata:chat_users:ip',
+            'firstping' => 'privacy:metadata:chat_users:firstping',
+            'lastping' => 'privacy:metadata:chat_users:lastping',
+            'lastmessageping' => 'privacy:metadata:chat_users:lastmessageping',
+            'lang' => 'privacy:metadata:chat_users:lang'
+        ], 'privacy:metadata:chat_users');
+
+        return $collection;
+    }
+
+    /**
+     * Get the list of contexts that contain user information for the specified user.
+     *
+     * @param int $userid The user to search.
+     * @return contextlist $contextlist The contextlist containing the list of contexts used in this plugin.
+     */
+    public static function get_contexts_for_userid(int $userid): \core_privacy\local\request\contextlist {
+        $contextlist = new \core_privacy\local\request\contextlist();
+
+        $sql = "
+            SELECT DISTINCT ctx.id
+              FROM {chat} c
+              JOIN {modules} m
+                ON m.name = :chat
+              JOIN {course_modules} cm
+                ON cm.instance = c.id
+               AND cm.module = m.id
+              JOIN {context} ctx
+                ON ctx.instanceid = cm.id
+               AND ctx.contextlevel = :modulelevel
+              JOIN {chat_messages} chm
+                ON chm.chatid = c.id
+             WHERE chm.userid = :userid";
+
+        $params = [
+            'chat' => 'chat',
+            'modulelevel' => CONTEXT_MODULE,
+            'userid' => $userid,
+        ];
+        $contextlist->add_from_sql($sql, $params);
+
+        return $contextlist;
+    }
+
+    /**
+     * Get the list of users who have data within a context.
+     *
+     * @param   userlist    $userlist   The userlist containing the list of users who have data in this context/plugin combination.
+     */
+    public static function get_users_in_context(userlist $userlist) {
+        $context = $userlist->get_context();
+
+        if (!is_a($context, \context_module::class)) {
+            return;
+        }
+
+        $params = [
+            'instanceid'    => $context->instanceid,
+            'modulename'    => 'chat',
+        ];
+
+        $sql = "SELECT chm.userid
+                  FROM {course_modules} cm
+                  JOIN {modules} m ON m.id = cm.module AND m.name = :modulename
+                  JOIN {chat} c ON c.id = cm.instance
+                  JOIN {chat_messages} chm ON chm.chatid = c.id
+                 WHERE cm.id = :instanceid";
+
+        $userlist->add_from_sql('userid', $sql, $params);
+    }
+
+    /**
+     * Export all user data for the specified user, in the specified contexts.
+     *
+     * @param approved_contextlist $contextlist The approved contexts to export information for.
+     */
+    public static function export_user_data(approved_contextlist $contextlist) {
+        global $DB;
+
+        $user = $contextlist->get_user();
+        $userid = $user->id;
+        $cmids = array_reduce($contextlist->get_contexts(), function($carry, $context) {
+            if ($context->contextlevel == CONTEXT_MODULE) {
+                $carry[] = $context->instanceid;
+            }
+            return $carry;
+        }, []);
+        if (empty($cmids)) {
+            return;
+        }
+
+        $chatidstocmids = static::get_chat_ids_to_cmids_from_cmids($cmids);
+        $chatids = array_keys($chatidstocmids);
+
+        // Export the messages.
+        list($insql, $inparams) = $DB->get_in_or_equal($chatids, SQL_PARAMS_NAMED);
+        $params = array_merge($inparams, ['userid' => $userid]);
+        $recordset = $DB->get_recordset_select('chat_messages', "chatid $insql AND userid = :userid", $params, 'timestamp, id');
+        static::recordset_loop_and_export($recordset, 'chatid', [], function($carry, $record) use ($user, $chatidstocmids) {
+            $message = $record->message;
+            if ($record->issystem) {
+                $message = get_string('message' . $record->message, 'mod_chat', fullname($user));
+            }
+            $carry[] = [
+                'message' => $message,
+                'sent_at' => transform::datetime($record->timestamp),
+                'is_system_generated' => transform::yesno($record->issystem),
+            ];
+            return $carry;
+
+        }, function($chatid, $data) use ($user, $chatidstocmids) {
+            $context = context_module::instance($chatidstocmids[$chatid]);
+            $contextdata = helper::get_context_data($context, $user);
+            $finaldata = (object) array_merge((array) $contextdata, ['messages' => $data]);
+            helper::export_context_files($context, $user);
+            writer::with_context($context)->export_data([], $finaldata);
+        });
+    }
+
+    /**
+     * Delete all data for all users in the specified context.
+     *
+     * @param context $context The specific context to delete data for.
+     */
+    public static function delete_data_for_all_users_in_context(context $context) {
+        global $DB;
+
+        if ($context->contextlevel != CONTEXT_MODULE) {
+            return;
+        }
+
+        $cm = get_coursemodule_from_id('chat', $context->instanceid);
+        if (!$cm) {
+            return;
+        }
+
+        $chatid = $cm->instance;
+        $DB->delete_records_select('chat_messages', 'chatid = :chatid', ['chatid' => $chatid]);
+        $DB->delete_records_select('chat_messages_current', 'chatid = :chatid', ['chatid' => $chatid]);
+        $DB->delete_records_select('chat_users', 'chatid = :chatid', ['chatid' => $chatid]);
+    }
+
+    /**
+     * Delete all user data for the specified user, in the specified contexts.
+     *
+     * @param approved_contextlist $contextlist The approved contexts and user information to delete information for.
+     */
+    public static function delete_data_for_user(approved_contextlist $contextlist) {
+        global $DB;
+
+        $userid = $contextlist->get_user()->id;
+        $cmids = array_reduce($contextlist->get_contexts(), function($carry, $context) {
+            if ($context->contextlevel == CONTEXT_MODULE) {
+                $carry[] = $context->instanceid;
+            }
+            return $carry;
+        }, []);
+        if (empty($cmids)) {
+            return;
+        }
+
+        $chatidstocmids = static::get_chat_ids_to_cmids_from_cmids($cmids);
+        $chatids = array_keys($chatidstocmids);
+
+        list($insql, $inparams) = $DB->get_in_or_equal($chatids, SQL_PARAMS_NAMED);
+        $sql = "chatid $insql AND userid = :userid";
+        $params = array_merge($inparams, ['userid' => $userid]);
+
+        $DB->delete_records_select('chat_messages', $sql, $params);
+        $DB->delete_records_select('chat_messages_current', $sql, $params);
+        $DB->delete_records_select('chat_users', $sql, $params);
+    }
+
+
+    /**
+     * Delete multiple users within a single context.
+     *
+     * @param   approved_userlist       $userlist The approved context and user information to delete information for.
+     */
+    public static function delete_data_for_users(approved_userlist $userlist) {
+        global $DB;
+
+        $context = $userlist->get_context();
+        $cm = $DB->get_record('course_modules', ['id' => $context->instanceid]);
+        $chat = $DB->get_record('chat', ['id' => $cm->instance]);
+
+        list($userinsql, $userinparams) = $DB->get_in_or_equal($userlist->get_userids(), SQL_PARAMS_NAMED);
+        $params = array_merge(['chatid' => $chat->id], $userinparams);
+        $sql = "chatid = :chatid AND userid {$userinsql}";
+
+        $DB->delete_records_select('chat_messages', $sql, $params);
+        $DB->delete_records_select('chat_messages_current', $sql, $params);
+        $DB->delete_records_select('chat_users', $sql, $params);
+    }
+
+    /**
+     * Return a dict of chat IDs mapped to their course module ID.
+     *
+     * @param array $cmids The course module IDs.
+     * @return array In the form of [$chatid => $cmid].
+     */
+    protected static function get_chat_ids_to_cmids_from_cmids(array $cmids) {
+        global $DB;
+        list($insql, $inparams) = $DB->get_in_or_equal($cmids, SQL_PARAMS_NAMED);
+        $sql = "
+            SELECT c.id, cm.id AS cmid
+              FROM {chat} c
+              JOIN {modules} m
+                ON m.name = :chat
+              JOIN {course_modules} cm
+                ON cm.instance = c.id
+               AND cm.module = m.id
+             WHERE cm.id $insql";
+        $params = array_merge($inparams, ['chat' => 'chat']);
+        return $DB->get_records_sql_menu($sql, $params);
+    }
+
+    /**
+     * Loop and export from a recordset.
+     *
+     * @param moodle_recordset $recordset The recordset.
+     * @param string $splitkey The record key to determine when to export.
+     * @param mixed $initial The initial data to reduce from.
+     * @param callable $reducer The function to return the dataset, receives current dataset, and the current record.
+     * @param callable $export The function to export the dataset, receives the last value from $splitkey and the dataset.
+     * @return void
+     */
+    protected static function recordset_loop_and_export(moodle_recordset $recordset, $splitkey, $initial,
+            callable $reducer, callable $export) {
+
+        $data = $initial;
+        $lastid = null;
+
+        foreach ($recordset as $record) {
+            if ($lastid && $record->{$splitkey} != $lastid) {
+                $export($lastid, $data);
+                $data = $initial;
+            }
+            $data = $reducer($data, $record);
+            $lastid = $record->{$splitkey};
+        }
+        $recordset->close();
+
+        if (!empty($lastid)) {
+            $export($lastid, $data);
+        }
+    }
+
+}

mod/chat/classes/search/activity.php

@@ -0,0 +1,46 @@
+<?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/>.
+
+/**
+ * Search area for mod_chat activities.
+ *
+ * @package    mod_chat
+ * @copyright  2015 David Monllao {@link http://www.davidmonllao.com}
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_chat\search;
+
+defined('MOODLE_INTERNAL') || die();
+
+/**
+ * Search area for mod_chat activities.
+ *
+ * @package    mod_chat
+ * @copyright  2015 David Monllao {@link http://www.davidmonllao.com}
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class activity extends \core_search\base_activity {
+
+    /**
+     * Returns true if this area uses file indexing.
+     *
+     * @return bool
+     */
+    public function uses_file_indexing() {
+        return true;
+    }
+}

mod/chat/classes/task/cron_task.php

@@ -0,0 +1,65 @@
+<?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 scheduled task for chat cron.
+ *
+ * @package    mod_chat
+ * @copyright  2019 Simey Lameze <simey@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+namespace mod_chat\task;
+
+defined('MOODLE_INTERNAL') || die();
+
+/**
+ * The main schedule task for the chat module.
+ *
+ * @package   mod_chat
+ * @copyright 2019 Simey Lameze <simey@moodle.com>
+ * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class cron_task extends \core\task\scheduled_task {
+
+    /**
+     * Get a descriptive name for this task (shown to admins).
+     *
+     * @return string
+     */
+    public function get_name() {
+        return get_string('crontask', 'mod_chat');
+    }
+
+    /**
+     * Run chat cron.
+     */
+    public function execute() {
+        global $CFG, $DB;
+        require_once($CFG->dirroot . '/mod/chat/lib.php');
+
+        chat_update_chat_times();
+        chat_delete_old_users();
+
+        $timenow = time();
+        $subselect = "SELECT c.keepdays
+                        FROM {chat} c
+                       WHERE c.id = {chat_messages}.chatid";
+        $DB->delete_records_select('chat_messages', "($subselect) > 0 AND timestamp < (? - ($subselect) * ?)",
+                [$timenow, DAYSECS]);
+
+        $DB->delete_records_select('chat_messages_current', "timestamp < ?", [$timenow - 8 * HOURSECS]);
+    }
+}