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Rewrite filter to also accept <a href="..."> and <video src="...">, f…
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…or example
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@justusdieckmann
justusdieckmann committed Mar 5, 2024
1 parent 48c2bf8 commit a80464e
Showing 1 changed file with 194 additions and 111 deletions.
305 changes: 194 additions & 111 deletions filter.php
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Original file line number Diff line number Diff line change
Expand Up @@ -20,39 +20,68 @@
* This filter will replace any links to opencast videos with the selected player from opencast.
*
* @package filter_opencast
* @copyright 2018 Tamara Gunkel
* @copyright 2024 Justus Dieckmann and Tamara Gunkel, University of Münster
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/


use mod_opencast\local\paella_transform;

/**
* Automatic opencast videos filter class.
*
* @package filter_opencast
* @copyright 2018 Tamara Gunkel
* @copyright 2024 Justus Dieckmann and Tamara Gunkel, University of Münster
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
class filter_opencast extends moodle_text_filter {

/**
* Get the content of the attribute $attributename from $tag.
* @param string $tag HTML-Tag.
* @param string $attributename Name of the attribute.
* @param string $attributecontentregex Regex of what the content of the attribute might be.
* @return string|null The content of the attribute or null, if it doesn't exist.
*/
private static function get_attribute(string $tag, string $attributename, string $attributecontentregex = '.*'): string|null {
$pattern = "/$attributename=(['\"])($attributecontentregex)\\1/";
preg_match($pattern, $tag, $matches);
return $matches[2] ?? null;
}

/**
* Test whether $url matches one of the episodeurls.
* @param string $url The url to test.
* @param array $episodeurls array of [ocinstanceid, episoderegex, baseurl].
* @return array|null [ocinstanceid, episodeid] or null if there are no matches.
*/
private static function test_url(string $url, array $episodeurls) : array|null {
foreach ($episodeurls as [$ocinstanceid, $episoderegex, $baseurl]) {
if (preg_match_all($episoderegex, $url, $matches)) {
return [$ocinstanceid, $matches[1][0]];
}
}
return null;
}

/**
* Replaces Opencast videos embedded in <video> tags by the paella player.
*
* @param string $text
* @param array $options
* @return array|mixed|string|string[]|null
* @throws dml_exception
*/
public function filter($text, array $options = []) {
global $PAGE, $OUTPUT;
$i = 0;

if (stripos($text, '</video>') === false) {
// Performance shortcut - if there is no </video> tag, nothing can match.
if (preg_match('</(a|video)>', $text) !== 1) {
// Performance shortcut - if there are no </video> or </a> tags, nothing can match.
return $text;
}

foreach (\tool_opencast\local\settings_api::get_ocinstances() as $ocinstance) {
// First section: (Relatively) quick check if there are episode urls in the text, and only look for these later.
// Improvable by combining all episode urls into one big regex if needed.
$ocinstances = \tool_opencast\local\settings_api::get_ocinstances();
$occurrences = [];
foreach ($ocinstances as $ocinstance) {
$episodeurls = get_config('filter_opencast', 'episodeurl_' . $ocinstance->id);

if (!$episodeurls) {
Expand All @@ -63,120 +92,174 @@ public function filter($text, array $options = []) {
$episodeurl = trim($episodeurl);

$urlparts = parse_url($episodeurl);
if (!isset($urlparts['scheme']) || !isset($urlparts['host'])) {
continue;
}
$baseurl = $urlparts['scheme'] . '://' . $urlparts['host'];
if (isset($urlparts['port'])) {
$baseurl .= ':' . $urlparts['port'];
}

if (empty($episodeurl) || stripos($text, $baseurl) === false) {
continue;
if (self::str_contains($text, $baseurl)) {
$episoderegex = "/" . preg_quote($episodeurl, "/") . "/";
$episoderegex = preg_replace('/\\\\\[EPISODEID\\\]/', '([0-9a-zA-Z\-]+)', $episoderegex);
$occurrences[] = [$ocinstance->id, $episoderegex, $baseurl];
}
}
}

// 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');
$video = false;
$width = false;
$height = false;

foreach ($matches as $match) {
if (empty(trim($match))) {
continue;
}
// Check if the match is a video tag.
if (substr($match, 0, 6) === "<video") {
$video = true;
preg_match('/width="([0-9]+)"/', $match, $width);
preg_match('/height="([0-9]+)"/', $match, $height);
$width = $width ? $width[1] : $width;
$height = $height ? $height[1] : $height;
} else if ($video) {
$video = false;
if (substr($match, 0, 7) === "<source") {

// Check if video is from opencast.
if (strpos($match, $baseurl) === false) {
$width = $height = 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];

// Get episode id from link.
$episoderegex = "/" . preg_quote($episodeurl, "/") . "/";
$episoderegex = preg_replace('/\\\\\[EPISODEID\\\]/', '([0-9a-zA-Z\-]+)', $episoderegex);
$nummatches = preg_match_all($episoderegex, $link, $episodeid);

if (!$nummatches) {
$width = $height = false;
continue;
}

$data = paella_transform::get_paella_data_json($ocinstance->id, $episodeid[1][0]);

if (!$data) {
continue;
}

// Collect the needed data being submitted to the template.
$mustachedata = new stdClass();
$mustachedata->playerid = 'ocplayer_' . $i++;
$mustachedata->configurl = (new moodle_url(get_config('filter_opencast', 'configurl_' . $ocinstance->id)))->out(false);
$mustachedata->themeurl = (new moodle_url(get_config('mod_opencast', 'themeurl_' . $ocinstance->id)))->out(false);
if (strpos($mustachedata->configurl, 'http') === false) {
$mustachedata->configurl = (new moodle_url($mustachedata->configurl))->out();
}

$mustachedata->data = json_encode($data);
$mustachedata->width = $width;
$mustachedata->height = $height;
$mustachedata->modplayerpath = (new moodle_url('/mod/opencast/player.html'))->out();

if (isset($data['streams'])) {
if (count($data['streams']) === 1) {
$sources = $data['streams'][0]['sources'];
$res = $sources[array_key_first($sources)][0]['res'];
$resolution = $res['w'] . '/' . $res['h'];
$mustachedata->resolution = $resolution;

if ($width xor $height) {
if ($width) {
$mustachedata->height = $width * ($res['h'] / $res['w']);
} else if ($height) {
$mustachedata->width = $height * ($res['w'] / $res['h']);
}
}
} else {
if ($width && $height) {
$mustachedata->width = $width;
$mustachedata->height = $height;
}
}
$newtext = $renderer->render_player($mustachedata);
} else {
$newtext = $OUTPUT->render(new \core\output\notification(
get_string('erroremptystreamsources', 'mod_opencast'),
\core\output\notification::NOTIFY_ERROR
));
}

// Replace video tag.
$text = preg_replace('/<video(?:(?!<\/video>).)*?' . preg_quote($match, '/') . '.*?<\/video>/s',
$newtext, $text, 1);
}
$width = $height = false;
if (empty($occurrences)) {
return $text;
}

// Second section: splitting the text into tags (and stuff between tags), and search for relevant urls in <a> and <video>.
$matches = preg_split('/(<[^>]*>)/i', $text, -1, PREG_SPLIT_NO_EMPTY | PREG_SPLIT_DELIM_CAPTURE);
if (!$matches) {
return $text;
}

$i = 0;
$newtext = '';

$episode = null;
$currenttag = null;
$texttoreplace = '';
$width = null;
$height = null;

// We go through the complete text and transfer it match by match to $newtext.
// While we are going through interesting tags, $currenttag is set to 'video' or 'a' respectively.
// During that time, the matches are transferred to $texttoreplace instead. When we find the matching closing tag,
// ... we add either $texttoreplace to $newtext, or the html for the video player, if we found a matching opencast url.
foreach ($matches as $match) {
if ($currenttag) {
$texttoreplace .= $match;
if (self::str_starts_with($match, "</$currenttag")) {
$replacement = null;
if ($episode) {
$replacement = self::render_player($episode[0], $episode[1], $i++, $width, $height);
}
if ($replacement) {
$newtext .= $replacement;
} else {
$newtext .= $texttoreplace;
}
$episode = null;
$width = null;
$height = null;
$texttoreplace = null;
$currenttag = null;
} else if (!$episode && $currenttag === 'video' && self::str_starts_with($match, '<source ')) {
$src = self::get_attribute($match, 'src');
if ($src) {
$episode = self::test_url($src, $occurrences);
}
}
} else {
if (self::str_starts_with($match, '<video ')) {
$currenttag = 'video';
$width = self::get_attribute($match, 'width', '[0-9]+');
$height = self::get_attribute($match, 'height', '[0-9]+');
$src = self::get_attribute($match, 'src');
if ($src) {
$episode = self::test_url($src, $occurrences);
}
} else if (self::str_starts_with($match, '<a ')) {
$src = self::get_attribute($match, 'href');
if ($src) {
$episode = self::test_url($src, $occurrences);
// Only set currenttag if there is a recognized url,
// ... so that nested <a> or <video> tags can be matched otherwise.
if ($episode) {
$currenttag = 'a';
}
}
}
if ($currenttag) {
$texttoreplace .= $match;
} else {
$newtext .= $match;
}
}
}

return $newtext;
}

/**
* Render HTML for embedding video player.
* @param int $ocinstanceid Id of ocinstance.
* @param string $episodeid Id opencast episode.
* @param int $playerid Unique id to assign to player element.
* @param int|null $width Optionally width for player.
* @param int|null $height Optionally height for player.
* @return string|null
*/
private static function render_player(int $ocinstanceid, string $episodeid, int $playerid,
$width = null, $height = null): string|null {
global $OUTPUT, $PAGE;

$data = paella_transform::get_paella_data_json($ocinstanceid, $episodeid);

if (!$data) {
return null;
}

// Collect the needed data being submitted to the template.
$mustachedata = new stdClass();
$mustachedata->playerid = 'ocplayer_' . $playerid;
$mustachedata->configurl =
(new moodle_url(get_config('filter_opencast', 'configurl_' . $ocinstanceid)))->out(false);
$mustachedata->themeurl =
(new moodle_url(get_config('mod_opencast', 'themeurl_' . $ocinstanceid)))->out(false);

$mustachedata->data = json_encode($data);
$mustachedata->width = $width;
$mustachedata->height = $height;
$mustachedata->modplayerpath = (new moodle_url('/mod/opencast/player.html'))->out(false);

if (isset($data['streams'])) {
if (count($data['streams']) === 1) {
$sources = $data['streams'][0]['sources'];
$res = $sources[array_key_first($sources)][0]['res'];
$resolution = $res['w'] . '/' . $res['h'];
$mustachedata->resolution = $resolution;

if ($width xor $height) {
if ($width) {
$mustachedata->height = $width * ($res['h'] / $res['w']);
} else if ($height) {
$mustachedata->width = $height * ($res['w'] / $res['h']);
}
}
}
$renderer = $PAGE->get_renderer('filter_opencast');
return $renderer->render_player($mustachedata);
} else {
return $OUTPUT->render(new \core\output\notification(
get_string('erroremptystreamsources', 'mod_opencast'),
\core\output\notification::NOTIFY_ERROR
));
}
}

// Return the same string except processed by the above.
return $text;
/**
* Polyfill for str_contains for PHP 7.
* @param string $haystack
* @param string $needle
* @return bool
*/
private static function str_contains(string $haystack, string $needle): bool {
return strpos($haystack, $needle) !== false;
}

/**
* Polyfill for str_starts_with for PHP 7.
* @param string $haystack
* @param string $needle
* @return bool
*/
private static function str_starts_with(string $haystack, string $needle): bool {
return strpos($haystack, $needle) === 0;
}
}

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