Proyectos de Subversion Moodle

<?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/>.

/**

 * This plugin is used to access Google Drive.

 *

 * @since Moodle 2.0

 * @package    repository_googledocs

 * @copyright  2009 Dan Poltawski <talktodan@gmail.com>

 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later

 */

defined('MOODLE_INTERNAL') || die();

require_once($CFG->dirroot . '/repository/lib.php');

require_once($CFG->libdir . '/filebrowser/file_browser.php');

use repository_googledocs\helper;

use repository_googledocs\googledocs_content_search;

/**

 * Google Docs Plugin

 *

 * @since Moodle 2.0

 * @package    repository_googledocs

 * @copyright  2009 Dan Poltawski <talktodan@gmail.com>

 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later

 */

class repository_googledocs extends repository {

    /**

     * OAuth 2 client

     * @var \core\oauth2\client

     */

    private $client = null;

    /**

     * OAuth 2 Issuer

     * @var \core\oauth2\issuer

     */

    private $issuer = null;

    /**

     * Additional scopes required for drive.

     */

    const SCOPES = 'https://www.googleapis.com/auth/drive';

    /** @var string Defines the path node identifier for the repository root. */

    const REPOSITORY_ROOT_ID = 'repository_root';

    /** @var string Defines the path node identifier for the my drive root. */

    const MY_DRIVE_ROOT_ID = 'root';

    /** @var string Defines the path node identifier for the shared drives root. */

    const SHARED_DRIVES_ROOT_ID = 'shared_drives_root';

    /** @var string Defines the path node identifier for the content search root. */

    const SEARCH_ROOT_ID = 'search';

    /**

     * Constructor.

     *

     * @param int $repositoryid repository instance id.

     * @param int|stdClass $context a context id or context object.

     * @param array $options repository options.

     * @param int $readonly indicate this repo is readonly or not.

     * @return void

     */

    public function __construct($repositoryid, $context = SYSCONTEXTID, $options = array(), $readonly = 0) {

        parent::__construct($repositoryid, $context, $options, $readonly = 0);

        try {

            $this->issuer = \core\oauth2\api::get_issuer(get_config('googledocs', 'issuerid'));

        } catch (dml_missing_record_exception $e) {

            $this->disabled = true;

        }

        if ($this->issuer && !$this->issuer->get('enabled')) {

            $this->disabled = true;

        }

    }

    /**

     * Get a cached user authenticated oauth client.

     *

     * @param moodle_url $overrideurl - Use this url instead of the repo callback.

     * @return \core\oauth2\client

     */

    protected function get_user_oauth_client($overrideurl = false) {

        if ($this->client) {

            return $this->client;

        }

        if ($overrideurl) {

            $returnurl = $overrideurl;

        } else {

            $returnurl = new moodle_url('/repository/repository_callback.php');

            $returnurl->param('callback', 'yes');

            $returnurl->param('repo_id', $this->id);

            $returnurl->param('sesskey', sesskey());

        }

        $this->client = \core\oauth2\api::get_user_oauth_client($this->issuer, $returnurl, self::SCOPES, true);

        return $this->client;

    }

    /**

     * Checks whether the user is authenticate or not.

     *

     * @return bool true when logged in.

     */

    public function check_login() {

        $client = $this->get_user_oauth_client();

        return $client->is_logged_in();

    }

    /**

     * Print or return the login form.

     *

     * @return void|array for ajax.

     */

    public function print_login() {

        $client = $this->get_user_oauth_client();

        $url = $client->get_login_url();

        if ($this->options['ajax']) {

            $popup = new stdClass();

            $popup->type = 'popup';

            $popup->url = $url->out(false);

            return array('login' => array($popup));

        } else {

            echo '<a target="_blank" href="'.$url->out(false).'">'.get_string('login', 'repository').'</a>';

        }

    }

    /**

     * Print the login in a popup.

     *

     * @param array|null $attr Custom attributes to be applied to popup div.

     */

    public function print_login_popup($attr = null) {

        global $OUTPUT, $PAGE;

        $client = $this->get_user_oauth_client(false);

        $url = new moodle_url($client->get_login_url());

        $state = $url->get_param('state') . '&reloadparent=true';

        $url->param('state', $state);

        $PAGE->set_pagelayout('embedded');

        echo $OUTPUT->header();

        $repositoryname = get_string('pluginname', 'repository_googledocs');

        $button = new single_button(

            $url,

            get_string('logintoaccount', 'repository', $repositoryname),

            'post',

            single_button::BUTTON_PRIMARY

        );

        $button->add_action(new popup_action('click', $url, 'Login'));

        $button->class = 'mdl-align';

        $button = $OUTPUT->render($button);

        echo html_writer::div($button, '', $attr);

        echo $OUTPUT->footer();

    }

    /**

     * Build the breadcrumb from a path.

     *

     * @deprecated since Moodle 3.11.

     * @param string $path to create a breadcrumb from.

     * @return array containing name and path of each crumb.

     */

    protected function build_breadcrumb($path) {

        debugging('The function build_breadcrumb() is deprecated, please use get_navigation() from the ' .

            'googledocs repository content classes instead.', DEBUG_DEVELOPER);

        $bread = explode('/', $path);

        $crumbtrail = '';

        foreach ($bread as $crumb) {

            list($id, $name) = $this->explode_node_path($crumb);

            $name = empty($name) ? $id : $name;

            $breadcrumb[] = array(

                'name' => $name,

                'path' => $this->build_node_path($id, $name, $crumbtrail)

            );

            $tmp = end($breadcrumb);

            $crumbtrail = $tmp['path'];

        }

        return $breadcrumb;

    }

    /**

     * Generates a safe path to a node.

     *

     * Typically, a node will be id|Name of the node.

     *

     * @deprecated since Moodle 3.11.

     * @param string $id of the node.

     * @param string $name of the node, will be URL encoded.

     * @param string $root to append the node on, must be a result of this function.

     * @return string path to the node.

     */

    protected function build_node_path($id, $name = '', $root = '') {

        debugging('The function build_node_path() is deprecated, please use ' .

            '\repository_googledocs\helper::build_node_path() instead.', DEBUG_DEVELOPER);

        $path = $id;

        if (!empty($name)) {

            $path .= '|' . urlencode($name);

        }

        if (!empty($root)) {

            $path = trim($root, '/') . '/' . $path;

        }

        return $path;

    }

    /**

     * Returns information about a node in a path.

     *

     * @deprecated since Moodle 3.11.

     * @see self::build_node_path()

     * @param string $node to extrat information from.

     * @return array about the node.

     */

    protected function explode_node_path($node) {

        debugging('The function explode_node_path() is deprecated, please use ' .

            '\repository_googledocs\helper::explode_node_path() instead.', DEBUG_DEVELOPER);

        if (strpos($node, '|') !== false) {

            list($id, $name) = explode('|', $node, 2);

            $name = urldecode($name);

        } else {

            $id = $node;

            $name = '';

        }

        $id = urldecode($id);

        return array(

            1 => $name,

            'id' => $id,

            'name' => $name

        );

    }

    /**

     * List the files and folders.

     *

     * @param  string $path path to browse.

     * @param  string $page page to browse.

     * @return array of result.

     */

    public function get_listing($path='', $page = '') {

        if (empty($path)) {

            $pluginname = get_string('pluginname', 'repository_googledocs');

            $path = helper::build_node_path('repository_root', $pluginname);

        }

        if (!$this->issuer->get('enabled')) {

            // Empty list of files for disabled repository.

            return [

                'dynload' => false,

                'list' => [],

                'nologin' => true,

            ];

        }

        // We analyse the path to extract what to browse.

        $trail = explode('/', $path);

        $uri = array_pop($trail);

        list($id, $name) = helper::explode_node_path($uri);

        $service = new repository_googledocs\rest($this->get_user_oauth_client());

        // Define the content class object and query which will be used to get the contents for this path.

        if ($id === self::SEARCH_ROOT_ID) {

            // The special keyword 'search' is the ID of the node. This is possible as we can set up a breadcrumb in

            // the search results. Therefore, we should use the content search object to get the results from the

            // previously performed search.

            $contentobj = new googledocs_content_search($service, $path);

            // We need to deconstruct the node name in order to obtain the search term and use it as a query.

            $query = str_replace(get_string('searchfor', 'repository_googledocs'), '', $name);

            $query = trim(str_replace("'", "", $query));

        } else {

            // Otherwise, return and use the appropriate (based on the path) content browser object.

            $contentobj = helper::get_browser($service, $path);

            // Use the node ID as a query.

            $query = $id;

        }

        return [

            'dynload' => true,

            'defaultreturntype' => $this->default_returntype(),

            'path' => $contentobj->get_navigation(),

            'list' => $contentobj->get_content_nodes($query, [$this, 'filter']),

            'manage' => 'https://drive.google.com/',

        ];

    }

    /**

     * Search throughout the Google Drive.

     *

     * @param string $searchtext text to search for.

     * @param int $page search page.

     * @return array of results.

     */

    public function search($searchtext, $page = 0) {

        // Construct the path to the repository root.

        $pluginname = get_string('pluginname', 'repository_googledocs');

        $rootpath = helper::build_node_path(self::REPOSITORY_ROOT_ID, $pluginname);

        // Construct the path to the search results node.

        // Currently, when constructing the search node name, the search term is concatenated to the lang string.

        // This was done deliberately so that we can easily and accurately obtain the search term from the search node

        // name later when navigating to the search results through the breadcrumb navigation.

        $name = get_string('searchfor', 'repository_googledocs') . " '{$searchtext}'";

        $path = helper::build_node_path(self::SEARCH_ROOT_ID, $name, $rootpath);

        $service = new repository_googledocs\rest($this->get_user_oauth_client());

        $searchobj = new googledocs_content_search($service, $path);

        return [

            'dynload' => true,

            'path' => $searchobj->get_navigation(),

            'list' => $searchobj->get_content_nodes($searchtext, [$this, 'filter']),

            'manage' => 'https://drive.google.com/',

        ];

    }

    /**

     * Query Google Drive for files and folders using a search query.

     *

     * Documentation about the query format can be found here:

     *   https://developers.google.com/drive/search-parameters

     *

     * This returns a list of files and folders with their details as they should be

     * formatted and returned by functions such as get_listing() or search().

     *

     * @deprecated since Moodle 3.11.

     * @param string $q search query as expected by the Google API.

     * @param string $path parent path of the current files, will not be used for the query.

     * @param int $page page.

     * @return array of files and folders.

     */

    protected function query($q, $path = null, $page = 0) {

        debugging('The function query() is deprecated, please use get_content_nodes() from the ' .

            'googledocs repository content classes instead.', DEBUG_DEVELOPER);

        global $OUTPUT;

        $files = array();

        $folders = array();

        $config = get_config('googledocs');

        $fields = "files(id,name,mimeType,webContentLink,webViewLink,fileExtension,modifiedTime,size,thumbnailLink,iconLink)";

        $params = array('q' => $q, 'fields' => $fields, 'spaces' => 'drive');

        try {

            // Retrieving files and folders.

            $client = $this->get_user_oauth_client();

            $service = new repository_googledocs\rest($client);

            $response = $service->call('list', $params);

        } catch (Exception $e) {

            if ($e->getCode() == 403 && strpos($e->getMessage(), 'Access Not Configured') !== false) {

                // This is raised when the service Drive API has not been enabled on Google APIs control panel.

                throw new repository_exception('servicenotenabled', 'repository_googledocs');

            } else {

                throw $e;

            }

        }

        $gfiles = isset($response->files) ? $response->files : array();

        foreach ($gfiles as $gfile) {

            if ($gfile->mimeType == 'application/vnd.google-apps.folder') {

                // This is a folder.

                $folders[$gfile->name . $gfile->id] = array(

                    'title' => $gfile->name,

                    'path' => $this->build_node_path($gfile->id, $gfile->name, $path),

                    'date' => strtotime($gfile->modifiedTime),

                    'thumbnail' => $OUTPUT->image_url(file_folder_icon())->out(false),

                    'thumbnail_height' => 64,

                    'thumbnail_width' => 64,

                    'children' => array()

                );

            } else {

                // This is a file.

                $link = isset($gfile->webViewLink) ? $gfile->webViewLink : '';

                if (empty($link)) {

                    $link = isset($gfile->webContentLink) ? $gfile->webContentLink : '';

                }

                if (isset($gfile->fileExtension)) {

                    // The file has an extension, therefore we can download it.

                    $source = json_encode([

                        'id' => $gfile->id,

                        'name' => $gfile->name,

                        'exportformat' => 'download',

                        'link' => $link

                    ]);

                    $title = $gfile->name;

                } else {

                    // The file is probably a Google Doc file, we get the corresponding export link.

                    // This should be improved by allowing the user to select the type of export they'd like.

                    $type = str_replace('application/vnd.google-apps.', '', $gfile->mimeType);

                    $title = '';

                    $exporttype = '';

                    $types = get_mimetypes_array();

                    switch ($type){

                        case 'document':

                            $ext = $config->documentformat;

                            $title = $gfile->name . '.gdoc';

                            if ($ext === 'rtf') {

                                // Moodle user 'text/rtf' as the MIME type for RTF files.

                                // Google uses 'application/rtf' for the same type of file.

                                // See https://developers.google.com/drive/v3/web/manage-downloads.

                                $exporttype = 'application/rtf';

                            } else {

                                $exporttype = $types[$ext]['type'];

                            }

                            break;

                        case 'presentation':

                            $ext = $config->presentationformat;

                            $title = $gfile->name . '.gslides';

                            $exporttype = $types[$ext]['type'];

                            break;

                        case 'spreadsheet':

                            $ext = $config->spreadsheetformat;

                            $title = $gfile->name . '.gsheet';

                            $exporttype = $types[$ext]['type'];

                            break;

                        case 'drawing':

                            $ext = $config->drawingformat;

                            $title = $gfile->name . '.'. $ext;

                            $exporttype = $types[$ext]['type'];

                            break;

                    }

                    // Skips invalid/unknown types.

                    if (empty($title)) {

                        continue;

                    }

                    $source = json_encode([

                        'id' => $gfile->id,

                        'exportformat' => $exporttype,

                        'link' => $link,

                        'name' => $gfile->name

                    ]);

                }

                // Adds the file to the file list. Using the itemId along with the name as key

                // of the array because Google Drive allows files with identical names.

                $thumb = '';

                if (isset($gfile->thumbnailLink)) {

                    $thumb = $gfile->thumbnailLink;

                } else if (isset($gfile->iconLink)) {

                    $thumb = $gfile->iconLink;

                }

                $files[$title . $gfile->id] = array(

                    'title' => $title,

                    'source' => $source,

                    'date' => strtotime($gfile->modifiedTime),

                    'size' => isset($gfile->size) ? $gfile->size : null,

                    'thumbnail' => $thumb,

                    'thumbnail_height' => 64,

                    'thumbnail_width' => 64,

                );

            }

        }

        // Filter and order the results.

        $files = array_filter($files, array($this, 'filter'));

        core_collator::ksort($files, core_collator::SORT_NATURAL);

        core_collator::ksort($folders, core_collator::SORT_NATURAL);

        return array_merge(array_values($folders), array_values($files));

    }

    /**

     * Logout.

     *

     * @return string

     */

    public function logout() {

        $client = $this->get_user_oauth_client();

        $client->log_out();

        return parent::logout();

    }

    /**

     * Get a file.

     *

     * @param string $reference reference of the file.

     * @param string $file name to save the file to.

     * @return string JSON encoded array of information about the file.

     */

    public function get_file($reference, $filename = '') {

        global $CFG;

        if (!$this->issuer->get('enabled')) {

            throw new repository_exception('cannotdownload', 'repository');

        }

        $source = json_decode($reference);

        $client = null;

        if (!empty($source->usesystem)) {

            $client = \core\oauth2\api::get_system_oauth_client($this->issuer);

        } else {

            $client = $this->get_user_oauth_client();

        }

        $base = 'https://www.googleapis.com/drive/v3';

        $newfilename = false;

        if ($source->exportformat == 'download') {

            $params = ['alt' => 'media'];

            $sourceurl = new moodle_url($base . '/files/' . $source->id, $params);

            $source = $sourceurl->out(false);

        } else {

            $params = ['mimeType' => $source->exportformat];

            $sourceurl = new moodle_url($base . '/files/' . $source->id . '/export', $params);

            $types = get_mimetypes_array();

            $checktype = $source->exportformat;

            if ($checktype == 'application/rtf') {

                $checktype = 'text/rtf';

            }

            // Determine the relevant default import format config for the given file.

            switch ($source->googledoctype) {

                case 'document':

                    $importformatconfig = get_config('googledocs', 'documentformat');

                    break;

                case 'presentation':

                    $importformatconfig = get_config('googledocs', 'presentationformat');

                    break;

                case 'spreadsheet':

                    $importformatconfig = get_config('googledocs', 'spreadsheetformat');

                    break;

                case 'drawing':

                    $importformatconfig = get_config('googledocs', 'drawingformat');

                    break;

                default:

                    $importformatconfig = null;

            }

            foreach ($types as $extension => $info) {

                if ($info['type'] == $checktype && $extension === $importformatconfig) {

                    $newfilename = $source->name . '.' . $extension;

                    break;

                }

            }

            $source = $sourceurl->out(false);

        }

        // We use download_one and not the rest API because it has special timeouts etc.

        $path = $this->prepare_file($filename);

        $options = ['filepath' => $path, 'timeout' => 15, 'followlocation' => true, 'maxredirs' => 5];

        $success = $client->download_one($source, null, $options);

        if ($success) {

            @chmod($path, $CFG->filepermissions);

            $result = [

                'path' => $path,

                'url' => $reference,

            ];

            if (!empty($newfilename)) {

                $result['newfilename'] = $newfilename;

            }

            return $result;

        }

        throw new repository_exception('cannotdownload', 'repository');

    }

    /**

     * Prepare file reference information.

     *

     * We are using this method to clean up the source to make sure that it

     * is a valid source.

     *

     * @param string $source of the file.

     * @return string file reference.

     */

    public function get_file_reference($source) {

        // We could do some magic upgrade code here.

        return $source;

    }

    /**

     * What kind of files will be in this repository?

     *

     * @return array return '*' means this repository support any files, otherwise

     *               return mimetypes of files, it can be an array

     */

    public function supported_filetypes() {

        return '*';

    }

    /**

     * Tells how the file can be picked from this repository.

     *

     * @return int

     */

    public function supported_returntypes() {

        // We can only support references if the system account is connected.

        if (!empty($this->issuer) && $this->issuer->is_system_account_connected()) {

            $setting = get_config('googledocs', 'supportedreturntypes');

            if ($setting == 'internal') {

                return FILE_INTERNAL;

            } else if ($setting == 'external') {

                return FILE_CONTROLLED_LINK;

            } else {

                return FILE_CONTROLLED_LINK | FILE_INTERNAL;

            }

        } else {

            return FILE_INTERNAL;

        }

    }

    /**

     * Which return type should be selected by default.

     *

     * @return int

     */

    public function default_returntype() {

        $setting = get_config('googledocs', 'defaultreturntype');

        $supported = get_config('googledocs', 'supportedreturntypes');

        if (($setting == FILE_INTERNAL && $supported != 'external') || $supported == 'internal') {

            return FILE_INTERNAL;

        } else {

            return FILE_CONTROLLED_LINK;

        }

    }

    /**

     * Return names of the general options.

     * By default: no general option name.

     *

     * @return array

     */

    public static function get_type_option_names() {

        return array('issuerid', 'pluginname',

            'documentformat', 'drawingformat',

            'presentationformat', 'spreadsheetformat',

            'defaultreturntype', 'supportedreturntypes');

    }

    /**

     * Store the access token.

     */

    public function callback() {

        $client = $this->get_user_oauth_client();

        // This will upgrade to an access token if we have an authorization code and save the access token in the session.

        $client->is_logged_in();

    }

    /**

     * Repository method to serve the referenced file

     *

     * @see send_stored_file

     *

     * @param stored_file $storedfile the file that contains the reference

     * @param int $lifetime Number of seconds before the file should expire from caches (null means $CFG->filelifetime)

     * @param int $filter 0 (default)=no filtering, 1=all files, 2=html files only

     * @param bool $forcedownload If true (default false), forces download of file rather than view in browser/plugin

     * @param array $options additional options affecting the file serving

     */

    public function send_file($storedfile, $lifetime=null , $filter=0, $forcedownload=false, array $options = null) {

        if (!$this->issuer->get('enabled')) {

            throw new repository_exception('cannotdownload', 'repository');

        }

        $source = json_decode($storedfile->get_reference());

        $fb = get_file_browser();

        $context = context::instance_by_id($storedfile->get_contextid(), MUST_EXIST);

        $info = $fb->get_file_info($context,

                                   $storedfile->get_component(),

                                   $storedfile->get_filearea(),

                                   $storedfile->get_itemid(),

                                   $storedfile->get_filepath(),

                                   $storedfile->get_filename());

        if (empty($options['offline']) && !empty($info) && $info->is_writable() && !empty($source->usesystem)) {

            // Add the current user as an OAuth writer.

            $systemauth = \core\oauth2\api::get_system_oauth_client($this->issuer);

            if ($systemauth === false) {

                $details = 'Cannot connect as system user';

                throw new repository_exception('errorwhilecommunicatingwith', 'repository', '', $details);

            }

            $systemservice = new repository_googledocs\rest($systemauth);

            // Get the user oauth so we can get the account to add.

            $url = moodle_url::make_pluginfile_url($storedfile->get_contextid(),

                                                   $storedfile->get_component(),

                                                   $storedfile->get_filearea(),

                                                   $storedfile->get_itemid(),

                                                   $storedfile->get_filepath(),

                                                   $storedfile->get_filename(),

                                                   $forcedownload);

            $url->param('sesskey', sesskey());

            $param = ($options['embed'] == true) ? false : $url;

            $userauth = $this->get_user_oauth_client($param);

            if (!$userauth->is_logged_in()) {

                if ($options['embed'] == true) {

                    // Due to Same-origin policy, we cannot redirect to googledocs login page.

                    // If the requested file is embed and the user is not logged in, add option to log in using a popup.

                    $this->print_login_popup(['style' => 'margin-top: 250px']);

                    exit;

                }

                redirect($userauth->get_login_url());

            }

            if ($userauth === false) {

                $details = 'Cannot connect as current user';

                throw new repository_exception('errorwhilecommunicatingwith', 'repository', '', $details);

            }

            $userinfo = $userauth->get_userinfo();

            $useremail = $userinfo['email'];

            $this->add_temp_writer_to_file($systemservice, $source->id, $useremail);

        }

        if (!empty($options['offline'])) {

            $downloaded = $this->get_file($storedfile->get_reference(), $storedfile->get_filename());

            $filename = $storedfile->get_filename();

            if (isset($downloaded['newfilename'])) {

                $filename = $downloaded['newfilename'];

            }

            send_file($downloaded['path'], $filename, $lifetime, $filter, false, $forcedownload, '', false, $options);

        } else if ($source->link) {

            // Do not use redirect() here because is not compatible with webservice/pluginfile.php.

            header('Location: ' . $source->link);

        } else {

            $details = 'File is missing source link';

            throw new repository_exception('errorwhilecommunicatingwith', 'repository', '', $details);

        }

    }

    /**

     * See if a folder exists within a folder

     *

     * @param \repository_googledocs\rest $client Authenticated client.

     * @param string $foldername The folder we are looking for.

     * @param string $parentid The parent folder we are looking in.

     * @return string|boolean The file id if it exists or false.

     */

    protected function folder_exists_in_folder(\repository_googledocs\rest $client, $foldername, $parentid) {

        $q = '\'' . addslashes($parentid) . '\' in parents and trashed = false and name = \'' . addslashes($foldername). '\'';

        $fields = 'files(id, name)';

        $params = [ 'q' => $q, 'fields' => $fields];

        $response = $client->call('list', $params);

        $missing = true;

        foreach ($response->files as $child) {

            if ($child->name == $foldername) {

                return $child->id;

            }

        }

        return false;

    }

    /**

     * Create a folder within a folder

     *

     * @param \repository_googledocs\rest $client Authenticated client.

     * @param string $foldername The folder we are creating.

     * @param string $parentid The parent folder we are creating in.

     *

     * @return string The file id of the new folder.

     */

    protected function create_folder_in_folder(\repository_googledocs\rest $client, $foldername, $parentid) {

        $fields = 'id';

        $params = ['fields' => $fields];

        $folder = ['mimeType' => 'application/vnd.google-apps.folder', 'name' => $foldername, 'parents' => [$parentid]];

        $created = $client->call('create', $params, json_encode($folder));

        if (empty($created->id)) {

            $details = 'Cannot create folder:' . $foldername;

            throw new repository_exception('errorwhilecommunicatingwith', 'repository', '', $details);

        }

        return $created->id;

    }

    /**

     * Get simple file info for humans.

     *

     * @param \repository_googledocs\rest $client Authenticated client.

     * @param string $fileid The file we are querying.

     *

     * @return stdClass

     */

    protected function get_file_summary(\repository_googledocs\rest $client, $fileid) {

        $fields = "id,name,owners,parents";

        $params = [

            'fileid' => $fileid,

            'fields' => $fields

        ];

        return $client->call('get', $params);

    }

    /**

     * Copy a file and return the new file details. A side effect of the copy

     * is that the owner will be the account authenticated with this oauth client.

     *

     * @param \repository_googledocs\rest $client Authenticated client.

     * @param string $fileid The file we are copying.

     * @param string $name The original filename (don't change it).

     *

     * @return stdClass file details.

     */

    protected function copy_file(\repository_googledocs\rest $client, $fileid, $name) {

        $fields = "id,name,mimeType,webContentLink,webViewLink,size,thumbnailLink,iconLink";

        $params = [

            'fileid' => $fileid,

            'fields' => $fields,

        ];

        // Keep the original name (don't put copy at the end of it).

        $copyinfo = [];

        if (!empty($name)) {

            $copyinfo = [ 'name' => $name ];

        }

        $fileinfo = $client->call('copy', $params, json_encode($copyinfo));

        if (empty($fileinfo->id)) {

            $details = 'Cannot copy file:' . $fileid;

            throw new repository_exception('errorwhilecommunicatingwith', 'repository', '', $details);

        }

        return $fileinfo;

    }

    /**

     * Add a writer to the permissions on the file (temporary).

     *

     * @param \repository_googledocs\rest $client Authenticated client.

     * @param string $fileid The file we are updating.

     * @param string $email The email of the writer account to add.

     * @return boolean

     */

    protected function add_temp_writer_to_file(\repository_googledocs\rest $client, $fileid, $email) {

        // Expires in 7 days.

        $expires = new DateTime();

        $expires->add(new DateInterval("P7D"));

        $updateeditor = [

            'emailAddress' => $email,

            'role' => 'writer',

            'type' => 'user',

            'expirationTime' => $expires->format(DateTime::RFC3339)

        ];

        $params = ['fileid' => $fileid, 'sendNotificationEmail' => 'false'];

        $response = $client->call('create_permission', $params, json_encode($updateeditor));

        if (empty($response->id)) {

            $details = 'Cannot add user ' . $email . ' as a writer for document: ' . $fileid;

            throw new repository_exception('errorwhilecommunicatingwith', 'repository', '', $details);

        }

        return true;

    }

    /**

     * Add a writer to the permissions on the file.

     *

     * @param \repository_googledocs\rest $client Authenticated client.

     * @param string $fileid The file we are updating.

     * @param string $email The email of the writer account to add.

     * @return boolean

     */

    protected function add_writer_to_file(\repository_googledocs\rest $client, $fileid, $email) {

        $updateeditor = [

            'emailAddress' => $email,

            'role' => 'writer',

            'type' => 'user'

        ];

        $params = ['fileid' => $fileid, 'sendNotificationEmail' => 'false'];

        $response = $client->call('create_permission', $params, json_encode($updateeditor));

        if (empty($response->id)) {

            $details = 'Cannot add user ' . $email . ' as a writer for document: ' . $fileid;

            throw new repository_exception('errorwhilecommunicatingwith', 'repository', '', $details);

        }

        return true;

    }

    /**

     * Move from root to folder

     *

     * @param \repository_googledocs\rest $client Authenticated client.

     * @param string $fileid The file we are updating.

     * @param string $folderid The id of the folder we are moving to

     * @return boolean

     */

    protected function move_file_from_root_to_folder(\repository_googledocs\rest $client, $fileid, $folderid) {

        // Set the parent.

        $params = [

            'fileid' => $fileid, 'addParents' => $folderid, 'removeParents' => 'root'

        ];

        $response = $client->call('update', $params, ' ');

        if (empty($response->id)) {

            $details = 'Cannot move the file to a folder: ' . $fileid;

            throw new repository_exception('errorwhilecommunicatingwith', 'repository', '', $details);

        }

        return true;

    }

    /**

     * Prevent writers from sharing.

     *

     * @param \repository_googledocs\rest $client Authenticated client.

     * @param string $fileid The file we are updating.

     * @return boolean

     */

    protected function prevent_writers_from_sharing_file(\repository_googledocs\rest $client, $fileid) {

        // We don't want anyone but Moodle to change the sharing settings.

        $params = [

            'fileid' => $fileid

        ];

        $update = [

            'writersCanShare' => false

        ];

        $response = $client->call('update', $params, json_encode($update));

        if (empty($response->id)) {

            $details = 'Cannot prevent writers from sharing document: ' . $fileid;

            throw new repository_exception('errorwhilecommunicatingwith', 'repository', '', $details);

        }

        return true;

    }

    /**

     * Allow anyone with the link to read the file.

     *

     * @param \repository_googledocs\rest $client Authenticated client.

     * @param string $fileid The file we are updating.

     * @return boolean

     */

    protected function set_file_sharing_anyone_with_link_can_read(\repository_googledocs\rest $client, $fileid) {

        $updateread = [

            'type' => 'anyone',

            'role' => 'reader',

            'allowFileDiscovery' => 'false'

        ];

        $params = ['fileid' => $fileid];

        $response = $client->call('create_permission', $params, json_encode($updateread));

        if (empty($response->id) || $response->id != 'anyoneWithLink') {

            $details = 'Cannot update link sharing for the document: ' . $fileid;

            throw new repository_exception('errorwhilecommunicatingwith', 'repository', '', $details);

        }

        return true;

    }

    /**

     * Called when a file is selected as a "link".

     * Invoked at MOODLE/repository/repository_ajax.php

     *

     * This is called at the point the reference files are being copied from the draft area to the real area

     * (when the file has really really been selected.

     *

     * @param string $reference this reference is generated by

     *                          repository::get_file_reference()

     * @param context $context the target context for this new file.

     * @param string $component the target component for this new file.

     * @param string $filearea the target filearea for this new file.

     * @param string $itemid the target itemid for this new file.

     * @return string updated reference (final one before it's saved to db).

     */

    public function reference_file_selected($reference, $context, $component, $filearea, $itemid) {

        global $CFG, $SITE;

        // What we need to do here is transfer ownership to the system user (or copy)

        // then set the permissions so anyone with the share link can view,

        // finally update the reference to contain the share link if it was not

        // already there (and point to new file id if we copied).

        // Get the details from the reference.

        $source = json_decode($reference);

        if (!empty($source->usesystem)) {

            // If we already copied this file to the system account - we are done.

            return $reference;

        }

        // Check this issuer is enabled.

        if ($this->disabled) {

            throw new repository_exception('cannotdownload', 'repository');

        }

        // Get a system oauth client and a user oauth client.

        $systemauth = \core\oauth2\api::get_system_oauth_client($this->issuer);

        if ($systemauth === false) {

            $details = 'Cannot connect as system user';

            throw new repository_exception('errorwhilecommunicatingwith', 'repository', '', $details);

        }

        // Get the system user email so we can share the file with this user.

        $systemuserinfo = $systemauth->get_userinfo();