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/>.

/**

 * Display H5P filter

 *

 * @package    filter_displayh5p

 * @copyright  2019 Victor Deniz <victor@moodle.com>

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

 */

defined('MOODLE_INTERNAL') || die;

use core_h5p\local\library\autoloader;

/**

 * Display H5P filter

 *

 * This filter will replace any occurrence of H5P URLs with the corresponding H5P content embed code

 *

 * @package    filter_displayh5p

 * @copyright  2019 Victor Deniz <victor@moodle.com>

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

 */

class filter_displayh5p extends moodle_text_filter {

    /**

     * @var boolean $loadresizerjs This is whether to request the resize.js script.

     */

    private static $loadresizerjs = true;

    /**

     * Function filter replaces any h5p-sources.

     *

     * @param  string $text    HTML content to process

     * @param  array  $options options passed to the filters

     * @return string

     */

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

        global $CFG, $USER;

        if (!is_string($text) or empty($text)) {

            // Non string data can not be filtered anyway.

            return $text;

        }

        // We are trying to minimize performance impact checking there's some H5P related URL.

        $h5purl = '(http[^ &<]*h5p)';

        if (!preg_match($h5purl, $text)) {

            return $text;

        }

        $allowedsources = get_config('filter_displayh5p', 'allowedsources');

        $allowedsources = array_filter(array_map('trim', explode("\n", $allowedsources)));

        $localsource = '('.preg_quote($CFG->wwwroot, '~').'/[^ &\#"\'<]*\.h5p([?][^ "\'<]*)?[^ \#"\'<]*)';

        $allowedsources[] = $localsource;

        $params = array(

            'tagbegin' => '<iframe src="',

            'tagend' => '</iframe>'

        );

        $specialchars = ['?', '&'];

        $escapedspecialchars = ['\?', '&'];

        $h5pcontents = array();

        $h5plinks = array();

        // Check all allowed sources.

        foreach ($allowedsources as $source) {

            // It is needed to add "/embed" at the end of URLs like https:://*.h5p.com/content/12345 (H5P.com).

            $params['urlmodifier'] = '';

            // Local files may display a button below the content to modify it when editing mode is on. This button will appear

            // only if the user has the proper capabilities.

            $params['canbeedited'] = (!empty($USER->editing)) && ($source == $localsource);

            if ($source == $localsource) {

                $params['tagbegin'] = '<iframe src="'.$CFG->wwwroot.'/h5p/embed.php?url=';

                $escapechars = $source;

                $ultimatepattern = $source;

            } else {

                if (!stripos($source, 'embed')) {

                    $params['urlmodifier'] = '/embed';

                }

                // Convert special chars.

                $sourceid = str_replace('[id]', '[0-9]+', $source);

                $escapechars = str_replace($specialchars, $escapedspecialchars, $sourceid);

                $ultimatepattern = '(' . $escapechars . ')';

            }

            // Improve performance creating filterobjects only when needed.

            if (!preg_match($ultimatepattern, $text)) {

                continue;

            }

            $h5pcontenturl = new filterobject($source, null, null, false,

                false, null, [$this, 'filterobject_prepare_replacement_callback'], $params + ['ish5plink' => false]);

            $h5pcontenturl->workregexp = '#'.$ultimatepattern.'#';

            $h5pcontents[] = $h5pcontenturl;

            // Regex to find h5p extensions in an <a> tag.

            $linkregexp = '~<a [^>]*href=["\']('.$escapechars.'[^"\']*)["\'][^>]*>([^<]*)</a>~is';

            $h5plinkurl = new filterobject($linkregexp, null, null, false,

                false, null, [$this, 'filterobject_prepare_replacement_callback'], $params + ['ish5plink' => true]);

            $h5plinkurl->workregexp = $linkregexp;

            $h5plinks[] = $h5plinkurl;

        }

        if (empty($h5pcontents) && empty($h5links)) {

            // No matches to deal with.

            return $text;

        }

        // Apply filter inside <a> tag href attribute.

        // We can not use filter_phrase function because it removes all tags and can not be applied in tag attributes.

        foreach ($h5plinks as $h5plink) {

            $text = preg_replace_callback($h5plink->workregexp,

                function ($matches) use ($h5plink) {

                    if ($matches[1] == $matches[2]) {

                        filter_prepare_phrase_for_replacement($h5plink);

                        return str_replace('$1', $matches[1], $h5plink->workreplacementphrase);

                    } else {

                        return $matches[0];

                    }

                }, $text);

        }

        // The "Edit" button below each H5P content will be displayed only for users with permissions to edit the content (to

        // avoid confusion). So the original H5P file behind this URL will be obtained and checked using the methods in the API.

        // As the H5P URL is required in order to get this information, this action can be done only here(the

        // prepare_replacement_callback method has only the placeholders).

        foreach ($h5pcontents as $h5pcontent) {

            $text = preg_replace_callback($h5pcontent->workregexp,

                function ($matches) use ($h5pcontent) {

                    global $USER, $CFG;

                    // The Edit button placeholder has been added only if the file can be edited.

                    if ($h5pcontent->replacementcallbackdata['canbeedited']) {

                        // If the content was originally a link, ignore it (it won't have the placeholder).

                        $matchurl = new \moodle_url($matches[0]);

                        if (strpos($matchurl->get_path(), 'h5p/embed.php') !== false) {

                            return $matches[0];

                        }

                        $contenturl = $matches[0];

                        list($file, $h5p) = \core_h5p\api::get_original_content_from_pluginfile_url($contenturl, true, true);

                        if ($file) {

                            filter_prepare_phrase_for_replacement($h5pcontent);

                            // Check if the user can edit this content.

                            if (\core_h5p\api::can_edit_content($file)) {

                                // If the user can modify the content, replace the placeholder with a link to the editor.

                                $title = get_string('editcontent', 'core_h5p');

                                $editorurl = $CFG->wwwroot . '/h5p/edit.php?url=' . $contenturl;

                                $htmlcode = html_writer::start_tag(

                                    'a',

                                    ['class' => 'autolink', 'title' => $title, 'href' => $editorurl]

                                );

                                $htmlcode .= $title . html_writer::end_tag('a');

                                $content = str_replace('$2', $htmlcode, $h5pcontent->workreplacementphrase);

                            } else {

                                // If the user can't edit the content, remove the placeholder.

                                $content = str_replace('$2', '', $h5pcontent->workreplacementphrase);

                            }

                            return str_replace('$1', $contenturl, $content);

                        }

                    }

                    return $matches[0];

                }, $text);

        }

        $result = filter_phrases($text, $h5pcontents, null, null, false, true);

        // Encoding H5P file URLs.

        // embed.php page is requesting a PARAM_LOCALURL url parameter, so for files/directories use non-alphanumeric

        // characters, we need to encode the parameter. Fetch url parameter added to embed.php and encode the whole url.

        $localurl = '#\?url=([^" <]*[\/]+[^" <]*\.h5p)([?][^"]*)?#';

        $result = preg_replace_callback($localurl,

            function ($matches) {

                $baseurl = rawurlencode($matches[1]);

                // Deal with possible parameters in the url link.

                if (!empty($matches[2])) {

                    $match = explode('?', $matches[2]);

                    if (!empty($match[1])) {

                        $baseurl = $baseurl."&".$match[1];

                    }

                }

                return "?url=".$baseurl;

            }, $result);

        return $result;

    }

    /**

     * Callback used by filterobject / filter_phrases.

     *

     * @param string $tagbegin HTML to insert before any match

     * @param string $tagend HTML to insert after any match

     * @param string $urlmodifier string to add to the match URL

     * @param bool $canbeedited Whether the content can be modified or not (to display a link to edit it or not).

     * @param bool $ish5plink Whether the original content comes from an H5P link or not.

     * @return array [$hreftagbegin, $hreftagend, $replacementphrase] for filterobject.

     */

    public function filterobject_prepare_replacement_callback($tagbegin, $tagend, $urlmodifier, $canbeedited, $ish5plink) {

        $sourceurl = "$1";

        if ($urlmodifier !== "") {

            $sourceurl .= $urlmodifier;

        }

        $h5piframesrc = $sourceurl . '" class="h5p-iframe" name="h5pcontent"' .

            ' style="height:230px; width: 100%; border: 0;" allowfullscreen="allowfullscreen">';

        // We want to request the resizing script only once.

        if (self::$loadresizerjs) {

            $resizerurl = autoloader::get_h5p_core_library_url('js/h5p-resizer.js');

            $tagend .= '<script src="' . $resizerurl->out() . '"></script>';

            self::$loadresizerjs = false;

        }

        if ($canbeedited && !$ish5plink) {

            // Placeholder to be replaced by the edit content button (depending on the user permissions).

            $tagend .= "$2";

        }

        return [$tagbegin, $tagend, $h5piframesrc];

    }

}