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236 lines
9.2 KiB
236 lines
9.2 KiB
2 years ago
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<?php
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// This file is part of Moodle - http://moodle.org/
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//
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// Moodle is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// Moodle is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with Moodle. If not, see <http://www.gnu.org/licenses/>.
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/**
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* Media plugin filtering
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*
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* This filter will replace any links to a media file with
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* a media plugin that plays that media inline
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*
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* @package filter
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* @subpackage mediaplugin
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* @copyright 2004 onwards Martin Dougiamas {@link http://moodle.com}
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* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
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*/
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defined('MOODLE_INTERNAL') || die();
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/**
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* Automatic media embedding filter class.
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*
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* It is highly recommended to configure servers to be compatible with our slasharguments,
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* otherwise the "?d=600x400" may not work.
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*
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* @package filter
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* @subpackage mediaplugin
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* @copyright 2004 onwards Martin Dougiamas {@link http://moodle.com}
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* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
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*/
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class filter_mediaplugin extends moodle_text_filter {
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/** @var bool True if currently filtering trusted text */
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private $trusted;
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/**
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* Setup page with filter requirements and other prepare stuff.
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*
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* @param moodle_page $page The page we are going to add requirements to.
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* @param context $context The context which contents are going to be filtered.
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*/
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public function setup($page, $context) {
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// This only requires execution once per request.
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static $jsinitialised = false;
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if ($jsinitialised) {
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return;
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}
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$jsinitialised = true;
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// Set up the media manager so that media plugins requiring JS are initialised.
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$mediamanager = core_media_manager::instance($page);
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}
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public function filter($text, array $options = array()) {
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global $CFG, $PAGE;
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if (!is_string($text) or empty($text)) {
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// non string data can not be filtered anyway
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return $text;
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}
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if (stripos($text, '</a>') === false && stripos($text, '</video>') === false && stripos($text, '</audio>') === false) {
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// Performance shortcut - if there are no </a>, </video> or </audio> tags, nothing can match.
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return $text;
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}
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// Check SWF permissions.
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$this->trusted = !empty($options['noclean']) or !empty($CFG->allowobjectembed);
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// Looking for tags.
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$matches = preg_split('/(<[^>]*>)/i', $text, -1, PREG_SPLIT_NO_EMPTY | PREG_SPLIT_DELIM_CAPTURE);
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if (!$matches) {
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return $text;
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}
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// Regex to find media extensions in an <a> tag.
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$embedmarkers = core_media_manager::instance()->get_embeddable_markers();
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$re = '~<a\s[^>]*href="([^"]*(?:' . $embedmarkers . ')[^"]*)"[^>]*>([^>]*)</a>~is';
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$newtext = '';
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$validtag = '';
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$tagname = '';
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$sizeofmatches = count($matches);
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// We iterate through the given string to find valid <a> tags
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// and build them so that the callback function can check it for
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// embedded content. Then we rebuild the string.
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foreach ($matches as $idx => $tag) {
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if (preg_match('|</'.$tagname.'>|', $tag) && !empty($validtag)) {
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$validtag .= $tag;
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// Given we now have a valid <a> tag to process it's time for
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// ReDoS protection. Stop processing if a word is too large.
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if (strlen($validtag) < 4096) {
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if ($tagname === 'a') {
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$processed = preg_replace_callback($re, array($this, 'callback'), $validtag);
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} else {
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// For audio and video tags we just process them without precheck for embeddable markers.
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$processed = $this->process_media_tag($validtag);
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}
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}
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// Rebuilding the string with our new processed text.
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$newtext .= !empty($processed) ? $processed : $validtag;
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// Wipe it so we can catch any more instances to filter.
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$validtag = '';
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$processed = '';
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} else if (preg_match('/<(a|video|audio)\s[^>]*/', $tag, $tagmatches) && $sizeofmatches > 1 &&
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(empty($validtag) || $tagname === strtolower($tagmatches[1]))) {
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// Looking for a starting tag. Ignore tags embedded into each other.
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$validtag = $tag;
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$tagname = strtolower($tagmatches[1]);
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} else {
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// If we have a validtag add to that to process later,
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// else add straight onto our newtext string.
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if (!empty($validtag)) {
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$validtag .= $tag;
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} else {
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$newtext .= $tag;
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}
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}
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}
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// Return the same string except processed by the above.
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return $newtext;
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}
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/**
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* Replace link with embedded content, if supported.
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*
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* @param array $matches
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* @return string
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*/
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private function callback(array $matches) {
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$mediamanager = core_media_manager::instance();
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global $CFG, $PAGE;
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// Check if we ignore it.
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if (preg_match('/class="[^"]*nomediaplugin/i', $matches[0])) {
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return $matches[0];
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}
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// Get name.
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$name = trim($matches[2]);
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if (empty($name) or strpos($name, 'http') === 0) {
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$name = ''; // Use default name.
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}
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// Split provided URL into alternatives.
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$urls = $mediamanager->split_alternatives($matches[1], $width, $height);
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$options = [core_media_manager::OPTION_ORIGINAL_TEXT => $matches[0]];
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return $this->embed_alternatives($urls, $name, $width, $height, $options);
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}
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/**
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* Renders media files (audio or video) using suitable embedded player.
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*
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* Wrapper for {@link core_media_manager::embed_alternatives()}
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*
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* @param array $urls Array of moodle_url to media files
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* @param string $name Optional user-readable name to display in download link
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* @param int $width Width in pixels (optional)
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* @param int $height Height in pixels (optional)
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* @param array $options Array of key/value pairs
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* @return string HTML content of embed
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*/
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protected function embed_alternatives($urls, $name, $width, $height, $options) {
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// Allow SWF (or not).
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if ($this->trusted) {
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$options[core_media_manager::OPTION_TRUSTED] = true;
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}
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// We could test whether embed is possible using can_embed, but to save
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// time, let's just embed it with the 'fallback to blank' option which
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// does most of the same stuff anyhow.
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$options[core_media_manager::OPTION_FALLBACK_TO_BLANK] = true;
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// NOTE: Options are not passed through from filter because the 'embed'
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// code does not recognise filter options (it's a different kind of
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// option-space) as it can be used in non-filter situations.
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$result = core_media_manager::instance()->embed_alternatives($urls, $name, $width, $height, $options);
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// If something was embedded, return it, otherwise return original.
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if ($result !== '') {
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return $result;
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} else {
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return $options[core_media_manager::OPTION_ORIGINAL_TEXT];
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}
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}
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/**
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* Replaces <video> or <audio> tag with processed contents
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*
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* @param string $fulltext complete HTML snipped "<video ...>...</video>" or "<audio ...>....</audio>"
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* @return string
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*/
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protected function process_media_tag($fulltext) {
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// Check if we ignore it.
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if (preg_match('/^<[^>]*class="[^"]*nomediaplugin/im', $fulltext)) {
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return $fulltext;
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}
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// Find all sources both as <video src=""> and as embedded <source> tags.
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$urls = [];
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if (preg_match('/^<[^>]*\bsrc="(.*?)"/im', $fulltext, $matches)) {
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$urls[] = new moodle_url($matches[1]);
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}
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if (preg_match_all('/<source\b[^>]*\bsrc="(.*?)"/im', $fulltext, $matches)) {
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foreach ($matches[1] as $url) {
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$urls[] = new moodle_url($url);
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}
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}
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// Extract width/height/title attributes and call embed_alternatives to find a suitable media player.
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if ($urls) {
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$options = [core_media_manager::OPTION_ORIGINAL_TEXT => $fulltext];
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$width = core_media_player_native::get_attribute($fulltext, 'width', PARAM_INT);
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$height = core_media_player_native::get_attribute($fulltext, 'height', PARAM_INT);
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$name = core_media_player_native::get_attribute($fulltext, 'title');
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return $this->embed_alternatives($urls, $name, $width, $height, $options);
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}
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return $fulltext;
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}
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}
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