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repository/nextcloud/classes/access_controlled_link_manager.php

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+<?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/>.
+
+/**
+ * Manages the creation and usage of access controlled links.
+ *
+ * @package    repository_nextcloud
+ * @copyright  2017 Nina Herrmann (Learnweb, University of Münster)
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+namespace repository_nextcloud;
+
+use context;
+use \core\oauth2\api;
+use \core\notification;
+use repository_exception;
+
+defined('MOODLE_INTERNAL') || die();
+require_once($CFG->libdir . '/webdavlib.php');
+
+/**
+ * Manages the creation and usage of access controlled links.
+ *
+ * @package    repository_nextcloud
+ * @copyright  2017 Nina Herrmann (Learnweb, University of Münster)
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class access_controlled_link_manager{
+    /**
+     * OCS client that uses the Open Collaboration Services REST API.
+     * @var ocs_client
+     */
+    protected $ocsclient;
+    /**
+     * ocsclient of the systemaccount.
+     * @var ocs_client
+     */
+    protected $systemocsclient;
+    /**
+     * Client to manage oauth2 features from the systemaccount.
+     * @var \core\oauth2\client
+     */
+    protected $systemoauthclient;
+    /**
+     * Client to manage webdav request from the systemaccount..
+     * @var \webdav_client
+     */
+    protected $systemwebdavclient;
+    /**
+     * Issuer from the oauthclient.
+     * @var \core\oauth2\issuer
+     */
+    protected $issuer;
+    /**
+     * Name of the related repository.
+     * @var string
+     */
+    protected $repositoryname;
+
+    /**
+     * Access_controlled_link_manager constructor.
+     * @param ocs_client $ocsclient
+     * @param \core\oauth2\client $systemoauthclient
+     * @param ocs_client $systemocsclient
+     * @param \core\oauth2\issuer $issuer
+     * @param string $repositoryname
+     * @throws configuration_exception
+     */
+    public function __construct($ocsclient, $systemoauthclient, $systemocsclient, $issuer, $repositoryname) {
+        $this->ocsclient = $ocsclient;
+        $this->systemoauthclient = $systemoauthclient;
+        $this->systemocsclient = $systemocsclient;
+
+        $this->repositoryname = $repositoryname;
+        $this->issuer = $issuer;
+        $this->systemwebdavclient = $this->create_system_dav();
+    }
+
+    /**
+     * Deletes the share of the systemaccount and a user. In case the share could not be deleted a notification is
+     * displayed.
+     * @param int $shareid Remote ID of the share to be deleted.
+     */
+    public function delete_share_dataowner_sysaccount($shareid) {
+        $shareid = (int) $shareid;
+        $deleteshareparams = [
+            'share_id' => $shareid
+        ];
+        $deleteshareresponse = $this->ocsclient->call('delete_share', $deleteshareparams);
+        $xml = simplexml_load_string($deleteshareresponse);
+
+        if (empty($xml->meta->statuscode) || $xml->meta->statuscode != 100 ) {
+            notification::warning('You just shared a file with a access controlled link.
+             However, the share between you and the systemaccount could not be deleted and is still present in your instance.');
+        }
+    }
+
+    /**
+     * Creates a share between a user and the system account. If $username is set the sharing direction is system account -> user,
+     * otherwise user -> system account.
+     * @param string $path Remote path of the file that will be shared
+     * @param string $username optional when set the file is shared with the corresponding user otherwise with
+     * the systemaccount.
+     * @param bool $maywrite if false, only(!) read access is granted.
+     * @return array statuscode, shareid, and filetarget
+     * @throws request_exception
+     */
+    public function create_share_user_sysaccount($path, $username = null, $maywrite = false) {
+        $result = array();
+
+        if ($username != null) {
+            $shareusername = $username;
+        } else {
+            $systemaccount = \core\oauth2\api::get_system_account($this->issuer);
+            $shareusername = $systemaccount->get('username');
+        }
+        $permissions = ocs_client::SHARE_PERMISSION_READ;
+        if ($maywrite) {
+            // Add more privileges (write, reshare) if allowed for the given user.
+            $permissions |= ocs_client::SHARE_PERMISSION_ALL;
+        }
+        $createshareparams = [
+            'path' => $path,
+            'shareType' => ocs_client::SHARE_TYPE_USER,
+            'publicUpload' => false,
+            'shareWith' => $shareusername,
+            'permissions' => $permissions,
+        ];
+
+        // File is now shared with the system account.
+        if ($username === null) {
+            $createshareresponse = $this->ocsclient->call('create_share', $createshareparams);
+        } else {
+            $createshareresponse = $this->systemocsclient->call('create_share', $createshareparams);
+        }
+        $xml = simplexml_load_string($createshareresponse);
+
+        $statuscode = (int)$xml->meta->statuscode;
+        if ($statuscode != 100 && $statuscode != 403) {
+            $details = get_string('filenotaccessed', 'repository_nextcloud');
+            throw new request_exception(get_string('request_exception',
+                'repository_nextcloud', array('instance' => $this->repositoryname, 'errormessage' => $details)));
+        }
+        $result['shareid'] = (int)$xml->data->id;
+        $result['statuscode'] = $statuscode;
+        $result['filetarget'] = (string)$xml->data[0]->file_target;
+
+        return $result;
+    }
+
+    /** Copy or moves a file to a new path.
+     * @param string $srcpath source path
+     * @param string $dstpath
+     * @param string $operation move or copy
+     * @param  \webdav_client $webdavclient needed when moving files.
+     * @return String Http-status of the request
+     * @throws configuration_exception
+     * @throws \coding_exception
+     * @throws \moodle_exception
+     * @throws \repository_nextcloud\request_exception
+     */
+    public function transfer_file_to_path($srcpath, $dstpath, $operation, $webdavclient = null) {
+        $this->systemwebdavclient->open();
+        $webdavendpoint = issuer_management::parse_endpoint_url('webdav', $this->issuer);
+
+        $srcpath = ltrim($srcpath, '/');
+        $sourcepath = $webdavendpoint['path'] . $srcpath;
+        $dstpath = ltrim($dstpath, '/');
+        $destinationpath = $webdavendpoint['path'] . $dstpath . '/' . $srcpath;
+
+        if ($operation === 'copy') {
+            $result = $this->systemwebdavclient->copy_file($sourcepath, $destinationpath, true);
+        } else if ($operation === 'move') {
+            $result = $webdavclient->move($sourcepath, $destinationpath, false);
+            if ($result == 412) {
+                // A file with that name already exists at that target. Find a unique location!
+                $increment = 0; // Will be appended to/inserted into the filename.
+                // Define the pattern that is used to insert the increment to the filename.
+                if (substr_count($srcpath, '.') === 0) {
+                    // No file extension; append increment to the (sprintf-escaped) name.
+                    $namepattern = str_replace('%', '%%', $destinationpath) . ' (%s)';
+                } else {
+                    // Append the increment to the second-to-last component, which is presumably the one before the extension.
+                    // Again, the original path is sprintf-escaped.
+                    $components = explode('.', str_replace('%', '%%', $destinationpath));
+                    $components[count($components) - 2] .= ' (%s)';
+                    $namepattern = implode('.', $components);
+                }
+            }
+            while ($result == 412) {
+                $increment++;
+                $destinationpath = sprintf($namepattern, $increment);
+                $result = $webdavclient->move($sourcepath, $destinationpath, false);
+            }
+        }
+        $this->systemwebdavclient->close();
+        if (!($result == 201 || $result == 204 || $result == 412)) {
+            $details = get_string('contactadminwith', 'repository_nextcloud',
+                'A webdav request to ' . $operation . ' a file failed.');
+            throw new request_exception(array('instance' => $this->repositoryname, 'errormessage' => $details));
+        }
+        return $result;
+    }
+
+    /**
+     * Creates a unique folder path for the access controlled link.
+     * @param context $context
+     * @param string $component
+     * @param string $filearea
+     * @param string $itemid
+     * @return string $result full generated path.
+     * @throws request_exception If the folder path cannot be created.
+     */
+    public function create_folder_path_access_controlled_links($context, $component, $filearea, $itemid) {
+        global $CFG, $SITE;
+        // The fullpath to store the file is generated from the context.
+        $contextlist = array_reverse($context->get_parent_contexts(true));
+        $fullpath = '';
+        $allfolders = [];
+        foreach ($contextlist as $ctx) {
+            // Prepare human readable context folders names, making sure they are still unique within the site.
+            $prevlang = force_current_language($CFG->lang);
+            $foldername = $ctx->get_context_name();
+            force_current_language($prevlang);
+
+            if ($ctx->contextlevel === CONTEXT_SYSTEM) {
+                // Append the site short name to the root folder.
+                $foldername .= ' ('.$SITE->shortname.')';
+                // Append the relevant object id.
+            } else if ($ctx->instanceid) {
+                $foldername .= ' (id '.$ctx->instanceid.')';
+            } else {
+                // This does not really happen but just in case.
+                $foldername .= ' (ctx '.$ctx->id.')';
+            }
+
+            $foldername = clean_param($foldername, PARAM_FILE);
+            $allfolders[] = $foldername;
+        }
+
+        $allfolders[] = clean_param($component, PARAM_FILE);
+        $allfolders[] = clean_param($filearea, PARAM_FILE);
+        $allfolders[] = clean_param($itemid, PARAM_FILE);
+
+        // Extracts the end of the webdavendpoint.
+        $parsedwebdavurl = issuer_management::parse_endpoint_url('webdav', $this->issuer);
+        $webdavprefix = $parsedwebdavurl['path'];
+        $this->systemwebdavclient->open();
+        // Checks whether folder exist and creates non-existent folders.
+        foreach ($allfolders as $foldername) {
+            $fullpath .= '/' . $foldername;
+            $isdir = $this->systemwebdavclient->is_dir($webdavprefix . $fullpath);
+            // Folder already exist, continue.
+            if ($isdir === true) {
+                continue;
+            }
+            $response = $this->systemwebdavclient->mkcol($webdavprefix . $fullpath);
+
+            if ($response != 201) {
+                $this->systemwebdavclient->close();
+                $details = get_string('contactadminwith', 'repository_nextcloud',
+                    get_string('pathnotcreated', 'repository_nextcloud', $fullpath));
+                throw new request_exception(array('instance' => $this->repositoryname,
+                    'errormessage' => $details));
+            }
+        }
+        $this->systemwebdavclient->close();
+        return $fullpath;
+    }
+
+    /** Creates a new webdav_client for the system account.
+     * @return \webdav_client
+     * @throws configuration_exception
+     */
+    public function create_system_dav() {
+        $webdavendpoint = issuer_management::parse_endpoint_url('webdav', $this->issuer);
+
+        // Selects the necessary information (port, type, server) from the path to build the webdavclient.
+        $server = $webdavendpoint['host'];
+        if ($webdavendpoint['scheme'] === 'https') {
+            $webdavtype = 'ssl://';
+            $webdavport = 443;
+        } else if ($webdavendpoint['scheme'] === 'http') {
+            $webdavtype = '';
+            $webdavport = 80;
+        }
+
+        // Override default port, if a specific one is set.
+        if (isset($webdavendpoint['port'])) {
+            $webdavport = $webdavendpoint['port'];
+        }
+
+        // Authentication method is `bearer` for OAuth 2. Pass oauth client from which WebDAV obtains the token when needed.
+        $dav = new \webdav_client($server, '', '', 'bearer', $webdavtype,
+            $this->systemoauthclient->get_accesstoken()->token, $webdavendpoint['path']);
+
+        $dav->port = $webdavport;
+        $dav->debug = false;
+        return $dav;
+    }
+
+    /** Creates a folder to store access controlled links.
+     * @param string $controlledlinkfoldername
+     * @param \webdav_client $webdavclient
+     * @throws \coding_exception
+     * @throws configuration_exception
+     * @throws request_exception
+     */
+    public function create_storage_folder($controlledlinkfoldername, $webdavclient) {
+        $parsedwebdavurl = issuer_management::parse_endpoint_url('webdav', $this->issuer);
+        $webdavprefix = $parsedwebdavurl['path'];
+        // Checks whether folder exist and creates non-existent folders.
+        $webdavclient->open();
+        $isdir = $webdavclient->is_dir($webdavprefix . $controlledlinkfoldername);
+        // Folder already exist, continue.
+        if (!$isdir) {
+            $responsecreateshare = $webdavclient->mkcol($webdavprefix . $controlledlinkfoldername);
+
+            if ($responsecreateshare != 201) {
+                $webdavclient->close();
+                throw new request_exception(array('instance' => $this->repositoryname,
+                    'errormessage' => get_string('contactadminwith', 'repository_nextcloud',
+                    'The folder to store files in the user account could not be created.')));
+            }
+        }
+        $webdavclient->close();
+    }
+
+    /** Gets all shares from a path (the path is file specific) and extracts the share of a specific user. In case
+     * multiple shares exist the first one is taken. Multiple shares can only appear when shares are created outside
+     * of this plugin, therefore this case is not handled.
+     * @param string $path
+     * @param string $username
+     * @return \SimpleXMLElement
+     * @throws \moodle_exception
+     */
+    public function get_shares_from_path($path, $username) {
+        $ocsparams = [
+            'path' => $path,
+            'reshares' => true
+        ];
+
+        $getsharesresponse = $this->systemocsclient->call('get_shares', $ocsparams);
+        $xml = simplexml_load_string($getsharesresponse);
+        $validelement = array();
+        foreach ($fileid = $xml->data->element as $element) {
+            if ($element->share_with == $username) {
+                $validelement = $element;
+                break;
+            }
+        }
+        if (empty($validelement)) {
+            throw new request_exception(array('instance' => $this->repositoryname,
+                'errormessage' => get_string('filenotaccessed', 'repository_nextcloud')));
+
+        }
+        return $validelement->id;
+    }
+
+    /** This method can only be used if the response is from a newly created share. In this case there is more information
+     * in the response. For a reference refer to
+     * https://docs.nextcloud.com/server/13/developer_manual/core/ocs-share-api.html#get-information-about-a-known-share.
+     * @param int $shareid
+     * @param string $username
+     * @return mixed the id of the share
+     * @throws \coding_exception
+     * @throws \repository_nextcloud\request_exception
+     */
+    public function get_share_information_from_shareid($shareid, $username) {
+        $ocsparams = [
+            'share_id' => (int) $shareid
+        ];
+
+        $shareinformation = $this->ocsclient->call('get_information_of_share', $ocsparams);
+        $xml = simplexml_load_string($shareinformation);
+        foreach ($fileid = $xml->data->element as $element) {
+            if ($element->share_with == $username) {
+                $validelement = $element;
+                break;
+            }
+        }
+        if (empty($validelement)) {
+            throw new request_exception(array('instance' => $this->repositoryname,
+                'errormessage' => get_string('filenotaccessed', 'repository_nextcloud')));
+
+        }
+        return (string) $validelement->file_target;
+    }
+
+    /**
+     * Find a file that has previously been shared with the system account.
+     * @param string $path Path to file in user context.
+     * @return array shareid: ID of share, filetarget: path to file in sys account.
+     * @throws request_exception If the share cannot be resolved.
+     */
+    public function find_share_in_sysaccount($path) {
+        $systemaccount = \core\oauth2\api::get_system_account($this->issuer);
+        $systemaccountuser = $systemaccount->get('username');
+
+        // Find out share ID from user files.
+        $ocsparams = [
+            'path' => $path,
+            'reshares' => true
+        ];
+
+        $getsharesresponse = $this->ocsclient->call('get_shares', $ocsparams);
+        $xml = simplexml_load_string($getsharesresponse);
+        $validelement = array();
+        foreach ($fileid = $xml->data->element as $element) {
+            if ($element->share_with == $systemaccountuser) {
+                $validelement = $element;
+                break;
+            }
+        }
+        if (empty($validelement)) {
+            throw new request_exception(array('instance' => $this->repositoryname,
+                'errormessage' => get_string('filenotaccessed', 'repository_nextcloud')));
+        }
+        $shareid = (int) $validelement->id;
+
+        // Use share id to find file name in system account's context.
+        $ocsparams = [
+            'share_id' => $shareid
+        ];
+
+        $shareinformation = $this->systemocsclient->call('get_information_of_share', $ocsparams);
+        $xml = simplexml_load_string($shareinformation);
+        foreach ($fileid = $xml->data->element as $element) {
+            if ($element->share_with == $systemaccountuser) {
+                $validfile = $element;
+                break;
+            }
+        }
+        if (empty($validfile)) {
+            throw new request_exception(array('instance' => $this->repositoryname,
+                'errormessage' => get_string('filenotaccessed', 'repository_nextcloud')));
+
+        }
+        return [
+            'shareid' => $shareid,
+            'filetarget' => (string) $validfile->file_target
+            ];
+    }
+
+    /**
+     * Download a file from the system account for the purpose of offline usage.
+     * @param string $srcpath Name of a file owned by the system account
+     * @param string $targetpath Temporary filename in Moodle
+     * @throws repository_exception The download was unsuccessful, maybe the file does not exist.
+     */
+    public function download_for_offline_usage(string $srcpath, string $targetpath): void {
+        $this->systemwebdavclient->open();
+        $webdavendpoint = issuer_management::parse_endpoint_url('webdav', $this->issuer);
+        $srcpath = ltrim($srcpath, '/');
+        $sourcepath = $webdavendpoint['path'] . $srcpath;
+
+        // Write file into temp location.
+        if (!$this->systemwebdavclient->get_file($sourcepath, $targetpath)) {
+            $this->systemwebdavclient->close();
+            throw new repository_exception('cannotdownload', 'repository');
+        }
+        $this->systemwebdavclient->close();
+    }
+}

repository/nextcloud/classes/configuration_exception.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/>.
+
+/**
+ * Exception for when client configuration data is missing.
+ *
+ * @package    repository_nextcloud
+ * @copyright  2017 Project seminar (Learnweb, University of Münster)
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace repository_nextcloud;
+
+defined('MOODLE_INTERNAL') || die();
+
+/**
+ * Exception for when client configuration data is missing.
+ *
+ * @package    repository_nextcloud
+ * @copyright  2017 Project seminar (Learnweb, University of Münster)
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class configuration_exception extends \moodle_exception {
+
+    /**
+     * This exception is used when the configuration of the plugin can not be processed or database entries are
+     * missing.
+     * @param string $hint optional param for additional information of the problem
+     * @param string $debuginfo detailed information how to fix problem
+     */
+    public function __construct($hint = '', $debuginfo = null) {
+        parent::__construct('configuration_exception', 'repository_nextcloud', '', $hint, $debuginfo);
+    }
+}

repository/nextcloud/classes/issuer_management.php

@@ -0,0 +1,87 @@
+<?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/>.
+//
+
+/**
+ * Provide static functions for creating and validating issuers.
+ *
+ * @package    repository_nextcloud
+ * @copyright  2018 Jan Dageförde (Learnweb, University of Münster)
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+namespace repository_nextcloud;
+
+defined('MOODLE_INTERNAL') || die();
+
+/**
+ * Provide static functions for creating and validating issuers.
+ *
+ * @package    repository_nextcloud
+ * @copyright  2018 Jan Dageförde (Learnweb, University of Münster)
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class issuer_management {
+
+    /**
+     * Check if an issuer provides all endpoints that are required by repository_nextcloud.
+     * @param \core\oauth2\issuer $issuer An issuer.
+     * @return bool True, if all endpoints exist; false otherwise.
+     */
+    public static function is_valid_issuer(\core\oauth2\issuer $issuer) {
+        $endpointwebdav = false;
+        $endpointocs = false;
+        $endpointtoken = false;
+        $endpointauth = false;
+        $endpointuserinfo = false;
+        $endpoints = \core\oauth2\api::get_endpoints($issuer);
+        foreach ($endpoints as $endpoint) {
+            $name = $endpoint->get('name');
+            switch ($name) {
+                case 'webdav_endpoint':
+                    $endpointwebdav = true;
+                    break;
+                case 'ocs_endpoint':
+                    $endpointocs = true;
+                    break;
+                case 'token_endpoint':
+                    $endpointtoken = true;
+                    break;
+                case 'authorization_endpoint':
+                    $endpointauth = true;
+                    break;
+                case 'userinfo_endpoint':
+                    $endpointuserinfo = true;
+                    break;
+            }
+        }
+        return $endpointwebdav && $endpointocs && $endpointtoken && $endpointauth && $endpointuserinfo;
+    }
+
+    /**
+     * Returns the parsed url parts of an endpoint of an issuer.
+     * @param string $endpointname
+     * @param \core\oauth2\issuer $issuer
+     * @return array parseurl [scheme => https/http, host=>'hostname', port=>443, path=>'path']
+     * @throws configuration_exception if an endpoint is undefined
+     */
+    public static function parse_endpoint_url(string $endpointname, \core\oauth2\issuer $issuer): array {
+        $url = $issuer->get_endpoint_url($endpointname);
+        if (empty($url)) {
+            throw new configuration_exception(get_string('endpointnotdefined', 'repository_nextcloud', $endpointname));
+        }
+        return parse_url($url);
+    }
+}

repository/nextcloud/classes/ocs_client.php

@@ -0,0 +1,179 @@
+<?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/>.
+
+/**
+ * REST interface to Nextcloud's implementation of Open Collaboration Services.
+ *
+ * @package    repository_nextcloud
+ * @copyright  2017 Jan Dageförde (Learnweb, University of Münster)
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+namespace repository_nextcloud;
+
+use core\oauth2\client;
+use core\oauth2\rest;
+
+defined('MOODLE_INTERNAL') || die();
+
+/**
+ * REST interface to Nextcloud's implementation of Open Collaboration Services.
+ *
+ * @package    repository_nextcloud
+ * @copyright  2017 Jan Dageförde (Learnweb, University of Münster)
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class ocs_client extends rest {
+
+    /**
+     * shareType=0 creates a private user share.
+     */
+    const SHARE_TYPE_USER = 0;
+
+    /**
+     * shareType=3 creates a public share.
+     */
+    const SHARE_TYPE_PUBLIC = 3;
+
+    /**
+     * permissions=1 gives read permission for a share.
+     */
+    const SHARE_PERMISSION_READ = 1;
+
+    /**
+     * permissions=1 gives read permission for a share.
+     */
+    const SHARE_PERMISSION_ALL = 31;
+
+    /**
+     * OCS endpoint as configured for the used issuer.
+     * @var \moodle_url
+     */
+    private $ocsendpoint;
+
+
+    /**
+     * Get endpoint URLs from the used issuer to use them in get_api_functions().
+     * @param client $oauthclient OAuth-authenticated Nextcloud client
+     * @throws configuration_exception Exception if critical endpoints are missing.
+     * @throws \moodle_exception when trying to construct a moodleurl
+     */
+    public function __construct(client $oauthclient) {
+        parent::__construct($oauthclient);
+
+        $issuer = $oauthclient->get_issuer();
+        $ocsendpoint = $issuer->get_endpoint_url('ocs');
+        if ($ocsendpoint === false) {
+            throw new configuration_exception('Endpoint ocs_endpoint not defined.');
+        }
+        $this->ocsendpoint = new \moodle_url($ocsendpoint);
+        if (empty($this->ocsendpoint->get_param('format'))) {
+            $this->ocsendpoint->params(array('format' => 'xml'));
+        }
+    }
+
+    /**
+     * Define relevant functions of the OCS API.
+     *
+     * Previously, the instruction to create a oauthclient recommended the user to enter the return format (format=xml).
+     * However, in this case the shareid is appended at the wrong place. Therefore, a new url is build which inserts the
+     * shareid at the suitable place for delete_share and get_information_of_share.
+     * create_share docs: https://docs.nextcloud.com/server/13/developer_manual/core/ocs-share-api.html#create-a-new-share
+     *
+     */
+    public function get_api_functions() {
+        return [
+            'create_share' => [
+                'endpoint' => $this->ocsendpoint->out(false),
+                'method' => 'post',
+                'args' => [
+                    'path' => PARAM_TEXT, // Could be PARAM_PATH, we really don't want to enforce a Moodle understanding of paths.
+                    'shareType' => PARAM_INT,
+                    'shareWith' => PARAM_TEXT, // Name of receiving user/group. Required if SHARE_TYPE_USER.
+                    'publicUpload' => PARAM_RAW, // Actually Boolean, but neither String-Boolean ('false') nor PARAM_BOOL (0/1).
+                    'permissions' => PARAM_INT,
+                    'shareWith' => PARAM_TEXT,
+                    'expireDate' => PARAM_TEXT
+                ],
+                'response' => 'text/xml'
+            ],
+            'delete_share' => [
+                'endpoint' => $this->build_share_url(),
+                'method' => 'delete',
+                'args' => [
+                    'share_id' => PARAM_INT
+                ],
+                'response' => 'text/xml'
+            ],
+            'get_shares' => [
+                'endpoint' => $this->ocsendpoint->out(false),
+                'method' => 'get',
+                'args' => [
+                    'path' => PARAM_TEXT,
+                    'reshares' => PARAM_RAW, // Returns not only the shares from the current user but all of the given file.
+                    'subfiles' => PARAM_RAW, // Returns all shares within a folder, given that path defines a folder.
+                ],
+                'response' => 'text/xml'
+            ],
+            'get_information_of_share' => [
+                'endpoint' => $this->build_share_url(),
+                'method' => 'get',
+                'args' => [
+                    'share_id' => PARAM_INT
+                ],
+                'response' => 'text/xml'
+            ],
+        ];
+    }
+
+    /**
+     * Private Function to return a url with the shareid in the path.
+     * @return string
+     */
+    private function build_share_url() {
+        // Out_omit_querystring() in combination with ocsendpoint->get_path() is not used since both function include
+        // /ocs/v1.php.
+        $shareurl = $this->ocsendpoint->get_scheme() . '://' . $this->ocsendpoint->get_host() . ':' .
+            $this->ocsendpoint->get_port() . $this->ocsendpoint->get_path() . '/{share_id}?' .
+            $this->ocsendpoint->get_query_string(false);
+        return $shareurl;
+    }
+
+    /**
+     * In POST requests, Moodle's REST API assumes that params are
+     * - transmitted as part of the URL or
+     * - expressed in JSON.
+     * Neither is true; we are passing an array to $functionargs which is then put into CURLOPT_POSTFIELDS.
+     * Curl assumes the content type to be `multipart/form-data` then, but the Moodle REST API tries to put
+     * a JSON content type. As a result, clients would fail.
+     * To make this less tedious to use, we assume that the params-as-array-in-$functionargs is the default for us.
+     *
+     * @param string $functionname Name of a function from get_api_functions()
+     * @param array $functionargs Request parameters
+     * @param bool|string $rawpost Optional param to include in the body of a post
+     * @param bool|string $contenttype Content type of the request body. Default: multipart/form-data if !$rawpost, JSON otherwise
+     * @return object|string
+     * @throws \coding_exception
+     * @throws \core\oauth2\rest_exception
+     */
+    public function call($functionname, $functionargs, $rawpost = false, $contenttype = false) {
+        if ($rawpost === false && $contenttype === false) {
+            return parent::call($functionname, $functionargs, false, 'multipart/form-data');
+        } else {
+            return parent::call($functionname, $functionargs, $rawpost, $contenttype);
+        }
+    }
+
+}

repository/nextcloud/classes/privacy/provider.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/>.
+
+/**
+ * Privacy provider.
+ *
+ * @package    repository_nextcloud
+ * @copyright  2018 Nina Herrmann (Learnweb, University of Münster)
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+namespace repository_nextcloud\privacy;
+
+defined('MOODLE_INTERNAL') || die();
+
+/**
+ * Privacy provider implementing null_provider.
+ *
+ * @package    repository_nextcloud
+ * @copyright  2018 Nina Herrmann (Learnweb, University of Münster)
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class provider implements \core_privacy\local\metadata\null_provider {
+
+    /**
+     * Get the language string identifier with the component's language
+     * file to explain why this plugin stores no data.
+     *
+     * @return  string
+     */
+    public static function get_reason(): string {
+        return 'privacy:metadata';
+    }
+}

repository/nextcloud/classes/request_exception.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/>.
+
+/**
+ * Exception for when an OCS request fails
+ *
+ * @package    repository_nextcloud
+ * @copyright  2017 Jan Dageförde (Learnweb, University of Münster)
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace repository_nextcloud;
+
+defined('MOODLE_INTERNAL') || die();
+
+/**
+ * Exception for when an OCS request fails
+ *
+ * @package    repository_nextcloud
+ * @copyright  2017 Jan Dageförde (Learnweb, University of Münster)
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class request_exception extends \moodle_exception {
+
+    /**
+     * An OCS request has failed.
+     *
+     * @param string $hint optional param for additional information of the problem
+     * @param string $debuginfo detailed information how to fix problem
+     */
+    public function __construct($hint = '', $debuginfo = null) {
+        parent::__construct('request_exception', 'repository_nextcloud', '', $hint, $debuginfo);
+    }
+}