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/>.

/**

 * The mod_bigbluebuttonbn files helper

 *

 * @package   mod_bigbluebuttonbn

 * @copyright 2021 onwards, Blindside Networks Inc

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

 * @author    Laurent David  (laurent [at] call-learning [dt] fr)

 */

namespace mod_bigbluebuttonbn\local\helpers;

use cache;

use cache_store;

use context;

use context_module;

use context_system;

use mod_bigbluebuttonbn\instance;

use moodle_url;

use stdClass;

/**

 * Utility class for all files routines helper

 *

 * @package mod_bigbluebuttonbn

 * @copyright 2021 onwards, Blindside Networks Inc

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

 */

class files {

    /**

     * Helper for validating pluginfile.

     *

     * @param stdClass $context context object

     * @param string $filearea file area

     *

     * @return bool|null false if file not valid

     */

    public static function pluginfile_valid(stdClass $context, string $filearea): ?bool {

        // Can be in context module or in context_system (if is the presentation by default).

        if (!in_array($context->contextlevel, [CONTEXT_MODULE, CONTEXT_SYSTEM])) {

            return false;

        }

        if (!array_key_exists($filearea, self::get_file_areas())) {

            return false;

        }

        return true;

    }

    /**

     * Helper for getting pluginfile.

     *

     * @param stdClass|null $course course object

     * @param stdClass|null $cm course module object

     * @param context $context context object

     * @param string $filearea file area

     * @param array $args extra arguments

     *

     * @return \stored_file|bool

     */

    public static function pluginfile_file(?stdClass $course, ?stdClass $cm, context $context, string $filearea, array $args) {

        $filename = self::get_plugin_filename($course, $cm, $context, $args);

        if (!$filename) {

            return false;

        }

        $fullpath = "/$context->id/mod_bigbluebuttonbn/$filearea/0/" . $filename;

        $fs = get_file_storage();

        $file = $fs->get_file_by_hash(sha1($fullpath));

        if (!$file || $file->is_directory()) {

            return false;

        }

        return $file;

    }

    /**

     * Get a full path to the file attached as a preuploaded presentation

     * or if there is none, set the presentation field will be set to blank.

     *

     * @param stdClass $bigbluebuttonformdata BigBlueButtonBN form data

     * Note that $bigbluebuttonformdata->presentation is the id of the filearea whereas the bbb instance table

     * stores the file name/path

     * @return string

     */

    public static function save_media_file(stdClass &$bigbluebuttonformdata): string {

        if (!isset($bigbluebuttonformdata->presentation) || $bigbluebuttonformdata->presentation == '') {

            return '';

        }

        $context = context_module::instance($bigbluebuttonformdata->coursemodule);

        // Set the filestorage object.

        $fs = get_file_storage();

        // Save the file if it exists that is currently in the draft area.

        file_save_draft_area_files($bigbluebuttonformdata->presentation, $context->id, 'mod_bigbluebuttonbn', 'presentation', 0);

        // Get the file if it exists.

        $files = $fs->get_area_files(

            $context->id,

            'mod_bigbluebuttonbn',

            'presentation',

            0,

            'itemid, filepath, filename',

            false

        );

        // Check that there is a file to process.

        $filesrc = '';

        if (count($files) == 1) {

            // Get the first (and only) file.

            $file = reset($files);

            $filesrc = '/' . $file->get_filename();

        }

        return $filesrc;

    }

    /**

     * Helper return array containing the file descriptor for a preuploaded presentation.

     *

     * @param context $context

     * @param string $presentation matching presentation file name

     * @param int $id bigbluebutton instance id

     * @param bool $withnonce add nonce to the url

     * @return array|null the representation of the presentation as an associative array

     */

    public static function get_presentation(context $context, string $presentation, $id = null, $withnonce = false): ?array {

        global $CFG;

        $fs = get_file_storage();

        $files = [];

        $defaultpresentation = $fs->get_area_files(

            context_system::instance()->id,

            'mod_bigbluebuttonbn',

            'presentationdefault',

            0,

            "filename",

            false

        );

        $activitypresentation = $files = $fs->get_area_files(

            $context->id,

            'mod_bigbluebuttonbn',

            'presentation',

            false,

            'itemid, filepath, filename',

            false

        );

        // Presentation upload logic based on config settings.

        if (empty($defaultpresentation)) {

            if (empty($activitypresentation) || !\mod_bigbluebuttonbn\local\config::get('preuploadpresentation_editable')) {

                return null;

            }

            $files = $activitypresentation;

        } else {

            if (empty($activitypresentation) || !\mod_bigbluebuttonbn\local\config::get('preuploadpresentation_editable')) {

                $files = $defaultpresentation;

                $id = null;

            } else {

                $files = $activitypresentation;

            }

        }

        $pnoncevalue = 0;

        if ($withnonce) {

            $nonceid = 0;

            if (!is_null($id)) {

                $instance = instance::get_from_instanceid($id);

                $nonceid = $instance->get_instance_id();

            }

            $pnoncevalue = self::generate_nonce($nonceid);

        }

        $file = null;

        foreach ($files as $f) {

            if (basename($f->get_filename()) == basename($presentation)) {

                $file = $f;

            }

        }

        if (!$file && !empty($files)) {

            $file = reset($files);

        }

        if (empty($file)) {

            return null; // File was not found.

        }

        // Note: $pnoncevalue is an int.

        $url = moodle_url::make_pluginfile_url(

            $file->get_contextid(),

            $file->get_component(),

            $file->get_filearea(),

            $withnonce ? $pnoncevalue : null, // Hack: item id as a nonce.

            $file->get_filepath(),

            $file->get_filename()

        );

        return [

            'icondesc' => get_mimetype_description($file),

            'iconname' => file_file_icon($file),

            'name' => $file->get_filename(),

            'url' => $url->out(false),

        ];

    }

    /**

     * Helper for getting pluginfile name.

     *

     * @param stdClass|null $course course object

     * @param stdClass|null $cm course module object

     * @param context $context context object

     * @param array $args extra arguments

     *

     * @return string|null

     */

    public static function get_plugin_filename(?stdClass $course, ?stdClass $cm, context $context, array $args): ?string {

        global $DB;

        if ($context->contextlevel != CONTEXT_SYSTEM) {

            // Plugin has a file to use as default in general setting.

            // The difference with the standard bigbluebuttonbn_pluginfile_filename() are.

            // - Context is system, so we don't need to check the cmid in this case.

            // - The area is "presentationdefault_cache".

            if (!$DB->get_record('bigbluebuttonbn', ['id' => $cm->instance])) {

                return null;

            }

        }

        // Plugin has a file to use as default in general setting.

        // The difference with the standard bigbluebuttonbn_pluginfile_filename() are.

        // - Context is system, so we don't need to check the cmid in this case.

        // - The area is "presentationdefault_cache".

        if (count($args) > 1) {

            $id = 0;

            if ($cm) {

                $instance = instance::get_from_cmid($cm->id);

                $id = $instance->get_instance_id();

            }

            $actualnonce = self::get_nonce($id);

            return ($args['0'] == $actualnonce) ? $args['1'] : null;

        }

        if (!empty($course)) {

            require_course_login($course, true, $cm, true, true);

        } else {

            require_login(null, true, $cm, true, true);

        }

        if (!has_capability('mod/bigbluebuttonbn:join', $context)) {

            return null;

        }

        return implode('/', $args);

    }

    /**

     * Helper generates a salt used for the preuploaded presentation callback url.

     *

     * @param int $id

     * @return int

     */

    protected static function get_nonce(int $id): int {

        $cache = static::get_nonce_cache();

        $pnoncekey = sha1($id);

        $existingnoncedata = $cache->get($pnoncekey);

        if ($existingnoncedata) {

            if ($existingnoncedata->counter > 0) {

                $existingnoncedata->counter--;

                $cache->set($pnoncekey, $existingnoncedata);

                return $existingnoncedata->nonce;

            }

        }

        // The item id was adapted for granting public access to the presentation once in order to allow BigBlueButton to gather

        // the file once.

        return static::generate_nonce($id);

    }

    /**

     * Generate a nonce and store it in the cache

     *

     * @param int $id

     * @return int

     */

    protected static function generate_nonce($id): int {

        $cache = static::get_nonce_cache();

        $pnoncekey = sha1($id);

        // The item id was adapted for granting public access to the presentation once in order to allow BigBlueButton to gather

        // the file once.

        $pnoncevalue = ((int) microtime()) + mt_rand();

        $cache->set($pnoncekey, (object) ['nonce' => $pnoncevalue, 'counter' => 2]);

        return $pnoncevalue;

    }

    /**

     * Get cache for nonce

     *

     * @return \cache_application|\cache_session|cache_store

     */

    private static function get_nonce_cache() {

        return cache::make_from_params(

            cache_store::MODE_APPLICATION,

            'mod_bigbluebuttonbn',

            'presentation_cache'

        );

    }

    /**

     * Returns an array of file areas.

     *

     * @return array a list of available file areas

     *

     */

    protected static function get_file_areas(): array {

        $areas = [];

        $areas['presentation'] = get_string('mod_form_block_presentation', 'bigbluebuttonbn');

        $areas['presentationdefault'] = get_string('mod_form_block_presentation_default', 'bigbluebuttonbn');

        return $areas;

    }

}