filter.php

<?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/>.

/**
 *  Opencast filtering
 *
 *  This filter will replace any links to opencast videos with the selected player from opencast.
 *
 * @package    filter
 * @subpackage opencast
 * @copyright  2018 Tamara Gunkel
 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */

defined('MOODLE_INTERNAL') || die();
require_once($CFG->dirroot . '/filter/opencast/lib.php');

/**
 * Automatic opencast videos filter class.
 *
 * @package    filter
 * @subpackage opencast
 * @copyright  2018 Tamara Gunkel
 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */
class filter_opencast extends moodle_text_filter {

    private static $loginrendered = false;

    public function filter($text, array $options = array()) {
        global $PAGE;

        if (stripos($text, '</video>') === false) {
            // Performance shortcut - if there are no </video> tags, nothing can match.
            return $text;
        }

        // Looking for tags.
        $matches = preg_split('/(<[^>]*>)/i', $text, -1, PREG_SPLIT_NO_EMPTY | PREG_SPLIT_DELIM_CAPTURE);

        if ($matches) {
            $renderer = $PAGE->get_renderer('filter_opencast');

            // Login if user is not logged in yet.
            $loggedin = true;
            if (!self::$loginrendered) {
                // Login and set cookie.
                filter_opencast_login();
                $loggedin = false;
                self::$loginrendered = true;
            }

            $video = false;

            foreach ($matches as $match) {
            	// Check if the match is a video tag.
                if (substr($match, 0, 6) === "<video") {
                    $video = true;
                } else if ($video) {
                    $video = false;
                    if (substr($match, 0, 7) === "<source") {

                        // Get baseurl either from engageurl setting or from opencast tool.
                        $baseurl = get_config('filter_opencast', 'engageurl');
                        if (empty($baseurl)) {
                            $baseurl = get_config('tool_opencast', 'apiurl');
                        }

                        // Check if video is from opencast.
                        if (strpos($match, $baseurl) === false) {
                            continue;
                        }

                        // Extract url.
                        preg_match_all('/<source[^>]+src=([\'"])(?<src>.+?)\1[^>]*>/i', $match, $result);

                        // Change url for loading the (Paella) Player.
                        $link = $result['src'][0];

                        if (strpos($link, 'http') !== 0) {
                            $link = 'http://' . $link;
                        }

                        // Create source with embedded mode.
                        $src = $link;

                        // Collect the needed data being submitted to the template.
                        $mustachedata = new stdClass();
                        $mustachedata->loggedin = $loggedin;
                        $mustachedata->src = $src;
                        $mustachedata->link = $link;

                        $newtext =  $renderer->render_player($mustachedata);

                        // Replace video tag.
                        $text = preg_replace('/<video(?:(?!<\/video>).)*?' . preg_quote($match, '/') . '.*?<\/video>/', $newtext, $text, 1);
                    }
                }
            }
        }

        // Return the same string except processed by the above.
        return $text;
    }
}