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, $USER;
  53
  54         if (!is_string($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             // Local files may display a button below the content to modify it when editing mode is on. This button will appear
  87             // only if the user has the proper capabilities.
  88             $params['canbeedited'] = (!empty($USER->editing)) && ($source == $localsource);
  89             if ($source == $localsource) {
  90                 $params['tagbegin'] = '<iframe src="'.$CFG->wwwroot.'/h5p/embed.php?url=';
  91                 $escapechars = $source;
  92                 $ultimatepattern = $source;
  93             } else {
  94                 if (!stripos($source, 'embed')) {
  95                     $params['urlmodifier'] = '/embed';
  96                 }
  97                 // Convert special chars.
  98                 $sourceid = str_replace('[id]', '[0-9]+', $source);
  99                 $escapechars = str_replace($specialchars, $escapedspecialchars, $sourceid);
 100                 $ultimatepattern = '(' . $escapechars . ')';
 101             }
 102
 103             // Improve performance creating filterobjects only when needed.
 104             if (!preg_match($ultimatepattern, $text)) {
 105                 continue;
 106             }
 107
 108             $h5pcontenturl = new filterobject($source, null, null, false,
 109                 false, null, [$this, 'filterobject_prepare_replacement_callback'], $params + ['ish5plink' => false]);
 110
 111             $h5pcontenturl->workregexp = '#'.$ultimatepattern.'#';
 112             $h5pcontents[] = $h5pcontenturl;
 113
 114             // Regex to find h5p extensions in an <a> tag.
 115             $linkregexp = '~<a [^>]*href=["\']('.$escapechars.'[^"\']*)["\'][^>]*>([^<]*)</a>~is';
 116
 117             $h5plinkurl = new filterobject($linkregexp, null, null, false,
 118                 false, null, [$this, 'filterobject_prepare_replacement_callback'], $params + ['ish5plink' => true]);
 119             $h5plinkurl->workregexp = $linkregexp;
 120             $h5plinks[] = $h5plinkurl;
 121         }
 122
 123         if (empty($h5pcontents) && empty($h5links)) {
 124             // No matches to deal with.
 125             return $text;
 126         }
 127
 128         // Apply filter inside <a> tag href attribute.
 129         // We can not use filter_phrase function because it removes all tags and can not be applied in tag attributes.
 130         foreach ($h5plinks as $h5plink) {
 131             $text = preg_replace_callback($h5plink->workregexp,
 132                 function ($matches) use ($h5plink) {
 133                     if ($matches[1] == $matches[2]) {
 134                         filter_prepare_phrase_for_replacement($h5plink);
 135
 136                         return str_replace('$1', $matches[1], $h5plink->workreplacementphrase);
 137                     } else {
 138                         return $matches[0];
 139                     }
 140                 }, $text);
 141         }
 142
 143         // The "Edit" button below each H5P content will be displayed only for users with permissions to edit the content (to
 144         // avoid confusion). So the original H5P file behind this URL will be obtained and checked using the methods in the API.
 145         // As the H5P URL is required in order to get this information, this action can be done only here(the
 146         // prepare_replacement_callback method has only the placeholders).
 147         foreach ($h5pcontents as $h5pcontent) {
 148             $text = preg_replace_callback($h5pcontent->workregexp,
 149                 function ($matches) use ($h5pcontent) {
 150                     global $USER, $CFG;
 151
 152                     // The Edit button placeholder has been added only if the file can be edited.
 153                     if ($h5pcontent->replacementcallbackdata['canbeedited']) {
 154                         // If the content was originally a link, ignore it (it won't have the placeholder).
 155                         $matchurl = new \moodle_url($matches[0]);
 156                         if (strpos($matchurl->get_path(), 'h5p/embed.php') !== false) {
 157                             return $matches[0];
 158                         }
 159
 160                         $contenturl = $matches[0];
 161                         list($file, $h5p) = \core_h5p\api::get_original_content_from_pluginfile_url($contenturl, true, true);
 162                         if ($file) {
 163                             filter_prepare_phrase_for_replacement($h5pcontent);
 164
 165                             // Check if the user can edit this content.
 166                             if (\core_h5p\api::can_edit_content($file)) {
 167                                 // If the user can modify the content, replace the placeholder with a link to the editor.
 168                                 $title = get_string('editcontent', 'core_h5p');
 169                                 $editorurl = $CFG->wwwroot . '/h5p/edit.php?url=' . $contenturl;
 170                                 $htmlcode = html_writer::start_tag(
 171                                     'a',
 172                                     ['class' => 'autolink', 'title' => $title, 'href' => $editorurl]
 173                                 );
 174                                 $htmlcode .= $title . html_writer::end_tag('a');
 175                                 $content = str_replace('$2', $htmlcode, $h5pcontent->workreplacementphrase);
 176                             } else {
 177                                 // If the user can't edit the content, remove the placeholder.
 178                                 $content = str_replace('$2', '', $h5pcontent->workreplacementphrase);
 179                             }
 180
 181                             return str_replace('$1', $contenturl, $content);
 182                         }
 183                     }
 184
 185                     return $matches[0];
 186                 }, $text);
 187         }
 188
 189         $result = filter_phrases($text, $h5pcontents, null, null, false, true);
 190
 191         // Encoding H5P file URLs.
 192         // embed.php page is requesting a PARAM_LOCALURL url parameter, so for files/directories use non-alphanumeric
 193         // characters, we need to encode the parameter. Fetch url parameter added to embed.php and encode the whole url.
 194         $localurl = '#\?url=([^" <]*[\/]+[^" <]*\.h5p)([?][^"]*)?#';
 195         $result = preg_replace_callback($localurl,
 196             function ($matches) {
 197                 $baseurl = rawurlencode($matches[1]);
 198                 // Deal with possible parameters in the url link.
 199                 if (!empty($matches[2])) {
 200                     $match = explode('?', $matches[2]);
 201                     if (!empty($match[1])) {
 202                         $baseurl = $baseurl."&".$match[1];
 203                     }
 204                 }
 205                 return "?url=".$baseurl;
 206             }, $result);
 207
 208         return $result;
 209     }
 210
 211     /**
 212      * Callback used by filterobject / filter_phrases.
 213      *
 214      * @param string $tagbegin HTML to insert before any match
 215      * @param string $tagend HTML to insert after any match
 216      * @param string $urlmodifier string to add to the match URL
 217      * @param bool $canbeedited Whether the content can be modified or not (to display a link to edit it or not).
 218      * @param bool $ish5plink Whether the original content comes from an H5P link or not.
 219      * @return array [$hreftagbegin, $hreftagend, $replacementphrase] for filterobject.
 220      */
 221     public function filterobject_prepare_replacement_callback($tagbegin, $tagend, $urlmodifier, $canbeedited, $ish5plink) {
 222
 223         $sourceurl = "$1";
 224         if ($urlmodifier !== "") {
 225             $sourceurl .= $urlmodifier;
 226         }
 227
 228         $h5piframesrc = $sourceurl . '" class="h5p-iframe" name="h5pcontent"' .
 229             ' style="height:230px; width: 100%; border: 0;" allowfullscreen="allowfullscreen">';
 230
 231         // We want to request the resizing script only once.
 232         if (self::$loadresizerjs) {
 233             $resizerurl = autoloader::get_h5p_core_library_url('js/h5p-resizer.js');
 234             $tagend .= '<script src="' . $resizerurl->out() . '"></script>';
 235             self::$loadresizerjs = false;
 236         }
 237
 238         if ($canbeedited && !$ish5plink) {
 239             // Placeholder to be replaced by the edit content button (depending on the user permissions).
 240             $tagend .= "$2";
 241         }
 242
 243         return [$tagbegin, $tagend, $h5piframesrc];
 244     }
 245 }