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 user's dropbox files

 *

 * @since Moodle 2.0

 * @package    repository_dropbox

 * @copyright  2012 Marina Glancy

 * @copyright  2010 Dongsheng Cai {@link http://dongsheng.org}

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

 */

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

/**

 * Repository to access Dropbox files

 *

 * @package    repository_dropbox

 * @copyright  2010 Dongsheng Cai

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

 */

class repository_dropbox extends repository {

    /**

     * @var dropbox     The instance of dropbox client.

     */

    private $dropbox;

    /**

     * @var int         The maximum file size to cache in the moodle filepool.

     */

    public $cachelimit = null;

    /**

     * Constructor of dropbox plugin.

     *

     * @inheritDocs

     */

    public function __construct($repositoryid, $context = SYSCONTEXTID, $options = []) {

        $options['page'] = optional_param('p', 1, PARAM_INT);

        parent::__construct($repositoryid, $context, $options);

        $returnurl = new moodle_url('/repository/repository_callback.php', [

                'callback'  => 'yes',

                'repo_id'   => $repositoryid,

                'sesskey'   => sesskey(),

            ]);

        // Create the dropbox API instance.

        $issuer = \core\oauth2\api::get_issuer(get_config('dropbox', 'dropbox_issuerid'));

        $this->dropbox = new repository_dropbox\dropbox($issuer, $returnurl);

    }

    /**

     * Repository method to serve the referenced file.

     *

     * @inheritDocs

     */

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

        $reference = $this->unpack_reference($storedfile->get_reference());

        $maxcachesize = $this->max_cache_bytes();

        if (empty($maxcachesize)) {

            // Always cache the file, regardless of size.

            $cachefile = true;

        } else {

            // Size available. Only cache if it is under maxcachesize.

            $cachefile = $storedfile->get_filesize() < $maxcachesize;

        }

        if (!$cachefile) {

            \core\session\manager::write_close();

            header('Location: ' . $this->get_file_download_link($reference->url));

            die;

        }

        try {

            $this->import_external_file_contents($storedfile, $this->max_cache_bytes());

            if (!is_array($options)) {

                $options = array();

            }

            $options['sendcachedexternalfile'] = true;

            \core\session\manager::write_close();

            send_stored_file($storedfile, $lifetime, $filter, $forcedownload, $options);

        } catch (moodle_exception $e) {

            // Redirect to Dropbox, it will show the error.

            // Note: We redirect to Dropbox shared link, not to the download link here!

            \core\session\manager::write_close();

            header('Location: ' . $reference->url);

            die;

        }

    }

    /**

     * Return human readable reference information.

     * {@link stored_file::get_reference()}

     *

     * @inheritDocs

     */

    public function get_reference_details($reference, $filestatus = 0) {

        global $USER;

        $ref  = unserialize($reference);

        $detailsprefix = $this->get_name();

        if (isset($ref->userid) && $ref->userid != $USER->id && isset($ref->username)) {

            $detailsprefix .= ' ('.$ref->username.')';

        }

        $details = $detailsprefix;

        if (isset($ref->path)) {

            $details .= ': '. $ref->path;

        }

        if (isset($ref->path) && !$filestatus) {

            // Indicate this is from dropbox with path.

            return $details;

        } else {

            if (isset($ref->url)) {

                $details = $detailsprefix. ': '. $ref->url;

            }

            return get_string('lostsource', 'repository', $details);

        }

    }

    /**

     * Cache file from external repository by reference.

     * {@link repository::get_file_reference()}

     * {@link repository::get_file()}

     * Invoked at MOODLE/repository/repository_ajax.php.

     *

     * @inheritDocs

     */

    public function cache_file_by_reference($reference, $storedfile) {

        try {

            $this->import_external_file_contents($storedfile, $this->max_cache_bytes());

        } catch (Exception $e) {

            // Cache failure should not cause a fatal error. This is only a nice-to-have feature.

        }

    }

    /**

     * Return the source information.

     *

     * The result of the function is stored in files.source field. It may be analysed

     * when the source file is lost or repository may use it to display human-readable

     * location of reference original.

     *

     * This method is called when file is picked for the first time only. When file

     * (either copy or a reference) is already in moodle and it is being picked

     * again to another file area (also as a copy or as a reference), the value of

     * files.source is copied.

     *

     * @inheritDocs

     */

    public function get_file_source_info($source) {

        global $USER;

        return 'Dropbox ('.fullname($USER).'): ' . $source;

    }

    /**

     * Prepare file reference information.

     *

     * @inheritDocs

     */

    public function get_file_reference($source) {

        global $USER;

        $reference = new stdClass;

        $reference->userid = $USER->id;

        $reference->username = fullname($USER);

        $reference->path = $source;

        // Determine whether we are downloading the file, or should use a file reference.

        $usefilereference = optional_param('usefilereference', false, PARAM_BOOL);

        if ($usefilereference) {

            if ($data = $this->dropbox->get_file_share_info($source)) {

                $reference = (object) array_merge((array) $data, (array) $reference);

            }

        }

        return serialize($reference);

    }

    /**

     * Return file URL for external link.

     *

     * @inheritDocs

     */

    public function get_link($reference) {

        $unpacked = $this->unpack_reference($reference);

        return $this->get_file_download_link($unpacked->url);

    }

    /**

     * Downloads a file from external repository and saves it in temp dir.

     *

     * @inheritDocs

     */

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

        $unpacked = $this->unpack_reference($reference);

        // This is a shared link, and hopefully it is still active.

        $downloadlink = $this->get_file_download_link($unpacked->url);

        $saveas = $this->prepare_file($saveas);

        file_put_contents($saveas, fopen($downloadlink, 'r'));

        return ['path' => $saveas];

    }

    /**

     * Dropbox plugin supports all kinds of files.

     *

     * @inheritDocs

     */

    public function supported_filetypes() {

        return '*';

    }

    /**

     * User cannot use the external link to dropbox.

     *

     * @inheritDocs

     */

    public function supported_returntypes() {

        return FILE_INTERNAL | FILE_REFERENCE | FILE_EXTERNAL;

    }

    /**

     * Get dropbox files.

     *

     * @inheritDocs

     */

    public function get_listing($path = '', $page = '1') {

        if (empty($path) || $path == '/') {

            $path = '';

        } else {

            $path = file_correct_filepath($path);

        }

        $list = [

                'list'      => [],

                'manage'    => 'https://www.dropbox.com/home',

                'logouturl' => 'https://www.dropbox.com/logout',

                'message'   => get_string('logoutdesc', 'repository_dropbox'),

                'dynload'   => true,

                'path'      => $this->process_breadcrumbs($path),

            ];

        // Note - we deliberately do not catch the coding exceptions here.

        try {

            $result = $this->dropbox->get_listing($path);

        } catch (\repository_dropbox\authentication_exception $e) {

            // The token has expired.

            return $this->print_login();

        } catch (\repository_dropbox\dropbox_exception $e) {

            // There was some other form of non-coding failure.

            // This could be a rate limit, or it could be a server-side error.

            // Just return early instead.

            return $list;

        }

        if (!is_object($result) || empty($result)) {

            return $list;

        }

        if (empty($result->entries) or !is_array($result->entries)) {

            return $list;

        }

        $list['list'] = $this->process_entries($result->entries);

        return $list;

    }

    /**

     * Get dropbox files in the specified path.

     *

     * @param   string      $query      The search query

     * @param   int         $page       The page number

     * @return  array

     */

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

        $list = [

                'list'      => [],

                'manage'    => 'https://www.dropbox.com/home',

                'logouturl' => 'https://www.dropbox.com/logout',

                'message'   => get_string('logoutdesc', 'repository_dropbox'),

                'dynload'   => true,

            ];

        // Note - we deliberately do not catch the coding exceptions here.

        try {

            $result = $this->dropbox->search($query);

        } catch (\repository_dropbox\authentication_exception $e) {

            // The token has expired.

            return $this->print_login();

        } catch (\repository_dropbox\dropbox_exception $e) {

            // There was some other form of non-coding failure.

            // This could be a rate limit, or it could be a server-side error.

            // Just return early instead.

            return $list;

        }

        if (!is_object($result) || empty($result)) {

            return $list;

        }

        if (empty($result->matches) or !is_array($result->matches)) {

            return $list;

        }

        $list['list'] = $this->process_entries($result->matches);

        return $list;

    }

    /**

     * Displays a thumbnail for current user's dropbox file.

     *

     * @inheritDocs

     */

    public function send_thumbnail($source) {

        $content = $this->dropbox->get_thumbnail($source);

        // Set 30 days lifetime for the image.

        // If the image is changed in dropbox it will have different revision number and URL will be different.

        // It is completely safe to cache the thumbnail in the browser for a long time.

        send_file($content, basename($source), 30 * DAYSECS, 0, true);

    }

    /**

     * Fixes references in DB that contains user credentials.

     *

     * @param   string      $packed     Content of DB field files_reference.reference

     * @return  string                  New serialized reference

     */

    protected function fix_old_style_reference($packed) {

        $ref = unserialize($packed);

        $ref = $this->dropbox->get_file_share_info($ref->path);

        if (!$ref || empty($ref->url)) {

            // Some error occurred, do not fix reference for now.

            return $packed;

        }

        $newreference = serialize($ref);

        if ($newreference !== $packed) {

            // We need to update references in the database.

            global $DB;

            $params = array(

                'newreference'  => $newreference,

                'newhash'       => sha1($newreference),

                'reference'     => $packed,

                'hash'          => sha1($packed),

                'repoid'        => $this->id,

            );

            $refid = $DB->get_field_sql('SELECT id FROM {files_reference}

                WHERE reference = :reference AND referencehash = :hash

                AND repositoryid = :repoid', $params);

            if (!$refid) {

                return $newreference;

            }

            $existingrefid = $DB->get_field_sql('SELECT id FROM {files_reference}

                    WHERE reference = :newreference AND referencehash = :newhash

                    AND repositoryid = :repoid', $params);

            if ($existingrefid) {

                // The same reference already exists, we unlink all files from it,

                // link them to the current reference and remove the old one.

                $DB->execute('UPDATE {files} SET referencefileid = :refid

                    WHERE referencefileid = :existingrefid',

                    array('refid' => $refid, 'existingrefid' => $existingrefid));

                $DB->delete_records('files_reference', array('id' => $existingrefid));

            }

            // Update the reference.

            $params['refid'] = $refid;

            $DB->execute('UPDATE {files_reference}

                SET reference = :newreference, referencehash = :newhash

                WHERE id = :refid', $params);

        }

        return $newreference;

    }

    /**

     * Unpack the supplied serialized reference, fixing it if required.

     *

     * @param   string      $packed     The packed reference

     * @return  object                  The unpacked reference

     */

    protected function unpack_reference($packed) {

        $reference = unserialize($packed);

        if (empty($reference->url)) {

            // The reference is missing some information. Attempt to update it.

            return unserialize($this->fix_old_style_reference($packed));

        }

        return $reference;

    }

    /**

     * Converts a URL received from dropbox API function 'shares' into URL that

     * can be used to download/access file directly

     *

     * @param string $sharedurl

     * @return string

     */

    protected function get_file_download_link($sharedurl) {

        $url = new \moodle_url($sharedurl);

        $url->param('dl', 1);

        return $url->out(false);

    }

    /**

     * Logout from dropbox.

     *

     * @inheritDocs

     */

    public function logout() {

        $this->dropbox->logout();

        return $this->print_login();

    }

    /**

     * Check if the dropbox is logged in via the oauth process.

     *

     * @inheritDocs

     */

    public function check_login() {

        return $this->dropbox->is_logged_in();

    }

    /**

     * Generate dropbox login url.

     *

     * @inheritDocs

     */

    public function print_login() {

        $url = $this->dropbox->get_login_url();

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

            $ret = array();

            $btn = new \stdClass();

            $btn->type = 'popup';

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

            $ret['login'] = array($btn);

            return $ret;

        } else {

            echo html_writer::link($url, get_string('login', 'repository'), array('target' => '_blank'));

        }

    }

    /**

     * Request access token.

     *

     * @inheritDocs

     */

    public function callback() {

        $this->dropbox->callback();

    }

    /**

     * Caches all references to Dropbox files in moodle filepool.

     *

     * Invoked by {@link repository_dropbox_cron()}. Only files smaller than

     * {@link repository_dropbox::max_cache_bytes()} and only files which

     * synchronisation timeout have not expired are cached.

     *

     * @inheritDocs

     */

    public function cron() {

        $fs = get_file_storage();

        $files = $fs->get_external_files($this->id);

        $fetchedreferences = [];

        foreach ($files as $file) {

            if (isset($fetchedreferences[$file->get_referencefileid()])) {

                continue;

            }

            try {

                // This call will cache all files that are smaller than max_cache_bytes()

                // and synchronise file size of all others.

                $this->import_external_file_contents($file, $this->max_cache_bytes());

                $fetchedreferences[$file->get_referencefileid()] = true;

            } catch (moodle_exception $e) {

                // If an exception is thrown, just continue. This is only a pre-fetch to help speed up general use.

            }

        }

    }

    /**

     * Add Plugin settings input to Moodle form.

     *

     * @inheritDocs

     */

    public static function type_config_form($mform, $classname = 'repository') {

        parent::type_config_form($mform);

        $options = [];

        $issuers = \core\oauth2\api::get_all_issuers();

        foreach ($issuers as $issuer) {

            $options[$issuer->get('id')] = s($issuer->get('name'));

        }

        $strrequired = get_string('required');

        $mform->addElement('select', 'dropbox_issuerid', get_string('issuer', 'repository_dropbox'), $options);

        $mform->addHelpButton('dropbox_issuerid', 'issuer', 'repository_dropbox');

        $mform->addRule('dropbox_issuerid', $strrequired, 'required', null, 'client');

        $mform->addElement('text', 'dropbox_cachelimit', get_string('cachelimit', 'repository_dropbox'), array('size' => '40'));

        $mform->addRule('dropbox_cachelimit', null, 'numeric', null, 'client');

        $mform->setType('dropbox_cachelimit', PARAM_INT);

        $mform->addElement('static', 'dropbox_cachelimit_info', '',  get_string('cachelimit_info', 'repository_dropbox'));

    }

    /**

     * Set options.

     *

     * @param   array   $options

     * @return  mixed

     */

    public function set_option($options = []) {

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

            set_config('dropbox_issuerid', trim($options['dropbox_issuerid']), 'dropbox');

            unset($options['dropbox_issuerid']);

        }

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

            $this->cachelimit = (int) trim($options['dropbox_cachelimit']);

            set_config('dropbox_cachelimit', $this->cachelimit, 'dropbox');

            unset($options['dropbox_cachelimit']);

        }

        return parent::set_option($options);

    }

    /**

     * Get dropbox options

     * @param string $config

     * @return mixed

     */

    public function get_option($config = '') {

        if ($config === 'dropbox_issuerid') {

            return trim(get_config('dropbox', 'dropbox_issuerid'));

        } else if ($config === 'dropbox_cachelimit') {

            return $this->max_cache_bytes();

        } else {

            $options = parent::get_option();

            $options['dropbox_issuerid'] = trim(get_config('dropbox', 'dropbox_issuerid'));

            $options['dropbox_cachelimit'] = $this->max_cache_bytes();

        }

        return $options;

    }

    /**

     * Return the OAuth 2 Redirect URI.

     *

     * @return  moodle_url

     */

    public static function get_oauth2callbackurl() {

        global $CFG;

        return new moodle_url('/admin/oauth2callback.php');

    }

    /**

     * Option names of dropbox plugin.

     *

     * @inheritDocs

     */

    public static function get_type_option_names() {

        return [

                'dropbox_issuerid',

                'pluginname',

                'dropbox_cachelimit',

            ];

    }

    /**

     * Performs synchronisation of an external file if the previous one has expired.

     *

     * This function must be implemented for external repositories supporting

     * FILE_REFERENCE, it is called for existing aliases when their filesize,

     * contenthash or timemodified are requested. It is not called for internal

     * repositories (see {@link repository::has_moodle_files()}), references to

     * internal files are updated immediately when source is modified.

     *

     * Referenced files may optionally keep their content in Moodle filepool (for

     * thumbnail generation or to be able to serve cached copy). In this

     * case both contenthash and filesize need to be synchronized. Otherwise repositories

     * should use contenthash of empty file and correct filesize in bytes.

     *

     * Note that this function may be run for EACH file that needs to be synchronised at the

     * moment. If anything is being downloaded or requested from external sources there

     * should be a small timeout. The synchronisation is performed to update the size of

     * the file and/or to update image and re-generated image preview. There is nothing

     * fatal if syncronisation fails but it is fatal if syncronisation takes too long

     * and hangs the script generating a page.

     *

     * Note: If you wish to call $file->get_filesize(), $file->get_contenthash() or

     * $file->get_timemodified() make sure that recursion does not happen.

     *

     * Called from {@link stored_file::sync_external_file()}

     *

     * @inheritDocs

     */

    public function sync_reference(stored_file $file) {

        global $CFG;

        if ($file->get_referencelastsync() + DAYSECS > time()) {

            // Only synchronise once per day.

            return false;

        }

        $reference = $this->unpack_reference($file->get_reference());

        if (!isset($reference->url)) {

            // The URL to sync with is missing.

            return false;

        }

        $c = new curl;

        $url = $this->get_file_download_link($reference->url);

        if (file_extension_in_typegroup($reference->path, 'web_image')) {

            $saveas = $this->prepare_file('');

            try {

                $result = $c->download_one($url, [], [

                        'filepath' => $saveas,

                        'timeout' => $CFG->repositorysyncimagetimeout,

                        'followlocation' => true,

                    ]);

                $info = $c->get_info();

                if ($result === true && isset($info['http_code']) && $info['http_code'] == 200) {

                    $file->set_synchronised_content_from_file($saveas);

                    return true;

                }

            } catch (Exception $e) {

                // IF the download_one fails, we will attempt to download

                // again with get() anyway.

            }

        }

        $c->get($url, null, array('timeout' => $CFG->repositorysyncimagetimeout, 'followlocation' => true, 'nobody' => true));

        $info = $c->get_info();

        if (isset($info['http_code']) && $info['http_code'] == 200 &&

                array_key_exists('download_content_length', $info) &&

                $info['download_content_length'] >= 0) {

            $filesize = (int)$info['download_content_length'];

            $file->set_synchronized(null, $filesize);

            return true;

        }

        $file->set_missingsource();

        return true;

    }

    /**

     * Process a standard entries list.

     *

     * @param   array       $entries    The list of entries returned from the API

     * @return  array                   The manipulated entries for display in the file picker

     */

    protected function process_entries(array $entries) {

        global $OUTPUT;

        $dirslist   = [];

        $fileslist  = [];

        foreach ($entries as $entry) {

            $entrydata = $entry;

            if (isset($entrydata->metadata)) {

                // If this is metadata, fetch the metadata content.

                // We only use the consistent parts of the file, folder, and metadata.

                $entrydata = $entrydata->metadata;

            }

            // Due to a change in the api, the actual content is in a nested metadata tree.

            if ($entrydata->{".tag"} == "metadata" && isset($entrydata->metadata)) {

                $entrydata = $entrydata->metadata;

            }

            if ($entrydata->{".tag"} === "folder") {

                $dirslist[] = [

                        'title'             => $entrydata->name,

                        // Use the display path here rather than lower.

                        // Dropbox is case insensitive but this leads to more accurate breadcrumbs.

                        'path'              => file_correct_filepath($entrydata->path_display),

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

                        'thumbnail_height'  => 64,

                        'thumbnail_width'   => 64,

                        'children'          => array(),

                    ];

            } else if ($entrydata->{".tag"} === "file") {

                $fileslist[] = [

                        'title'             => $entrydata->name,

                        // Use the path_lower here to make life easier elsewhere.

                        'source'            => $entrydata->path_lower,

                        'size'              => $entrydata->size,

                        'date'              => strtotime($entrydata->client_modified),

                        'thumbnail'         => $OUTPUT->image_url(file_extension_icon($entrydata->path_lower))->out(false),

                        'realthumbnail'     => $this->get_thumbnail_url($entrydata),

                        'thumbnail_height'  => 64,

                        'thumbnail_width'   => 64,

                    ];

            }

        }

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

        return array_merge($dirslist, array_values($fileslist));

    }

    /**

     * Process the breadcrumbs for a listing.

     *

     * @param   string      $path       The path to create breadcrumbs for

     * @return  array

     */

    protected function process_breadcrumbs($path) {

        // Process breadcrumb trail.

        // Note: Dropbox is case insensitive.

        // Without performing an additional API call, it isn't possible to get the path_display.

        // As a result, the path here is the path_lower.

        $breadcrumbs = [

            [

                'path' => '/',

                'name' => get_string('dropbox', 'repository_dropbox'),

            ],

        ];

        $path = rtrim($path, '/');

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

        $pathtodate = '';

        foreach ($directories as $directory) {

            if ($directory === '') {

                continue;

            }

            $pathtodate .= '/' . $directory;

            $breadcrumbs[] = [

                    'path'  => $pathtodate,

                    'name'  => $directory,

                ];

        }

        return $breadcrumbs;

    }

    /**

     * Grab the thumbnail URL for the specified entry.

     *

     * @param   object      $entry      The file entry as retrieved from the API

     * @return  moodle_url

     */

    protected function get_thumbnail_url($entry) {

        if ($this->dropbox->supports_thumbnail($entry)) {

            $thumburl = new moodle_url('/repository/dropbox/thumbnail.php', [

                // The id field in dropbox is unique - no need to specify a revision.

                'source'    => $entry->id,

                'path'      => $entry->path_lower,

                'repo_id'   => $this->id,

                'ctx_id'    => $this->context->id,

            ]);

            return $thumburl->out(false);

        }

        return '';

    }

    /**

     * Returns the maximum size of the Dropbox files to cache in moodle.

     *

     * Note that {@link repository_dropbox::sync_reference()} will try to cache images even

     * when they are bigger in order to generate thumbnails. However there is

     * a small timeout for downloading images for synchronisation and it will

     * probably fail if the image is too big.

     *

     * @return int

     */

    public function max_cache_bytes() {

        if ($this->cachelimit === null) {

            $this->cachelimit = (int) get_config('dropbox', 'dropbox_cachelimit');

        }

        return $this->cachelimit;

    }

}