filter/displayh5p/filter.php

   1 <?php
   2 // This file is part of Moodle - http://moodle.org/
   3 //
   4 // Moodle is free software: you can redistribute it and/or modify
   5 // it under the terms of the GNU General Public License as published by
   6 // the Free Software Foundation, either version 3 of the License, or
   7 // (at your option) any later version.
   8 //
   9 // Moodle is distributed in the hope that it will be useful,
  10 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 // GNU General Public License for more details.
  13 //
  14 // You should have received a copy of the GNU General Public License
  15 // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
  16 /**
  17  * Display H5P filter
  18  *
  19  * @package    filter_displayh5p
  20  * @copyright  2019 Victor Deniz <victor@moodle.com>
  21  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  22  */
  23
  24 defined('MOODLE_INTERNAL') || die;
  25
  26 use core_h5p\local\library\autoloader;
  27
  28 /**
  29  * Display H5P filter
  30  *
  31  * This filter will replace any occurrence of H5P URLs with the corresponding H5P content embed code
  32  *
  33  * @package    filter_displayh5p
  34  * @copyright  2019 Victor Deniz <victor@moodle.com>
  35  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  36  */
  37 class filter_displayh5p extends moodle_text_filter {
  38
  39     /**
  40      * @var boolean $loadresizerjs This is whether to request the resize.js script.
  41      */
  42     private static $loadresizerjs = true;
  43
  44     /**
  45      * Function filter replaces any h5p-sources.
  46      *
  47      * @param  string $text    HTML content to process
  48      * @param  array  $options options passed to the filters
  49      * @return string
  50      */
  51     public function filter($text, array $options = array()) {
  52         global $CFG;
  53
  54         if (!is_string($text) or empty($text)) {
  55             // Non string data can not be filtered anyway.
  56             return $text;
  57         }
  58
  59         // We are trying to minimize performance impact checking there's some H5P related URL.
  60         $h5purl = '(http[^ &<]*h5p)';
  61         if (!preg_match($h5purl, $text)) {
  62             return $text;
  63         }
  64
  65         $allowedsources = get_config('filter_displayh5p', 'allowedsources');
  66         $allowedsources = array_filter(array_map('trim', explode("\n", $allowedsources)));
  67
  68         $localsource = '('.preg_quote($CFG->wwwroot).'/[^ &\#"\'<]*\.h5p([?][^ "\'<]*)?[^ \#"\'<]*)';
  69         $allowedsources[] = $localsource;
  70
  71         $params = array(
  72             'tagbegin' => '<iframe src="',
  73             'tagend' => '</iframe>'
  74         );
  75
  76         $specialchars = ['?', '&'];
  77         $escapedspecialchars = ['\?', '&amp;'];
  78         $h5pcontents = array();
  79         $h5plinks = array();
  80
  81         // Check all allowed sources.
  82         foreach ($allowedsources as $source) {
  83             // It is needed to add "/embed" at the end of URLs like https:://*.h5p.com/content/12345 (H5P.com).
  84             $params['urlmodifier'] = '';
  85
  86             if (($source == $localsource)) {
  87                 $params['tagbegin'] = '<iframe src="'.$CFG->wwwroot.'/h5p/embed.php?url=';
  88                 $escapechars = $source;
  89                 $ultimatepattern = $source;
  90             } else {
  91                 if (!stripos($source, 'embed')) {
  92                     $params['urlmodifier'] = '/embed';
  93                 }
  94                 // Convert special chars.
  95                 $sourceid = str_replace('[id]', '[0-9]+', $source);
  96                 $escapechars = str_replace($specialchars, $escapedspecialchars, $sourceid);
  97                 $ultimatepattern = '(' . $escapechars . ')';
  98             }
  99
 100             // Improve performance creating filterobjects only when needed.
 101             if (!preg_match($ultimatepattern, $text)) {
 102                 continue;
 103             }
 104
 105             $h5pcontenturl = new filterobject($source, null, null, false,
 106                 false, null, [$this, 'filterobject_prepare_replacement_callback'], $params);
 107
 108             $h5pcontenturl->workregexp = '#'.$ultimatepattern.'#';
 109             $h5pcontents[] = $h5pcontenturl;
 110
 111             // Regex to find h5p extensions in an <a> tag.
 112             $linkregexp = '~<a [^>]*href=["\']('.$escapechars.'[^"\']*)["\'][^>]*>([^<]*)</a>~is';
 113
 114             $h5plinkurl = new filterobject($linkregexp, null, null, false,
 115                 false, null, [$this, 'filterobject_prepare_replacement_callback'], $params);
 116             $h5plinkurl->workregexp = $linkregexp;
 117             $h5plinks[] = $h5plinkurl;
 118         }
 119
 120         if (empty($h5pcontents) && empty($h5links)) {
 121             // No matches to deal with.
 122             return $text;
 123         }
 124
 125         // Apply filter inside <a> tag href attribute.
 126         // We can not use filter_phrase function because it removes all tags and can not be applied in tag attributes.
 127         foreach ($h5plinks as $h5plink) {
 128             $text = preg_replace_callback($h5plink->workregexp,
 129                 function ($matches) use ($h5plink) {
 130                     if ($matches[1] == $matches[2]) {
 131                         filter_prepare_phrase_for_replacement($h5plink);
 132
 133                         return str_replace('$1', $matches[1], $h5plink->workreplacementphrase);
 134                     } else {
 135                         return $matches[0];
 136                     }
 137                 }, $text);
 138
 139         }
 140
 141         $result = filter_phrases($text, $h5pcontents, null, null, false, true);
 142
 143         // Encoding H5P file URLs.
 144         // embed.php page is requesting a PARAM_LOCALURL url parameter, so for files/directories use non-alphanumeric
 145         // characters, we need to encode the parameter. Fetch url parameter added to embed.php and encode the whole url.
 146         $localurl = '#\?url=([^" <]*[\/]+[^" <]*\.h5p)([?][^"]*)?#';
 147         $result = preg_replace_callback($localurl,
 148             function ($matches) {
 149                 $baseurl = rawurlencode($matches[1]);
 150                 // Deal with possible parameters in the url link.
 151                 if (!empty($matches[2])) {
 152                     $match = explode('?', $matches[2]);
 153                     if (!empty($match[1])) {
 154                         $baseurl = $baseurl."&".$match[1];
 155                     }
 156                 }
 157                 return "?url=".$baseurl;
 158             }, $result);
 159
 160         return $result;
 161     }
 162
 163     /**
 164      * Callback used by filterobject / filter_phrases.
 165      *
 166      * @param string $tagbegin HTML to insert before any match
 167      * @param string $tagend HTML to insert after any match
 168      * @param string $urlmodifier string to add to the match URL
 169      * @return array [$hreftagbegin, $hreftagend, $replacementphrase] for filterobject.
 170      */
 171     public function filterobject_prepare_replacement_callback($tagbegin, $tagend, $urlmodifier) {
 172         $sourceurl = "$1";
 173         if ($urlmodifier !== "") {
 174             $sourceurl .= $urlmodifier;
 175         }
 176
 177         $h5piframesrc = $sourceurl . '" class="h5p-iframe" name="h5pcontent"' .
 178             ' style="height:230px; width: 100%; border: 0;" allowfullscreen="allowfullscreen">';
 179
 180         // We want to request the resizing script only once.
 181         if (self::$loadresizerjs) {
 182             $resizerurl = autoloader::get_h5p_core_library_url('js/h5p-resizer.js');
 183             $tagend .= '<script src="' . $resizerurl->out() . '"></script>';
 184             self::$loadresizerjs = false;
 185         }
 186
 187         return [$tagbegin, $tagend, $h5piframesrc];
 188     }
 189 }