HTMLPurifier Youtube iframe-embed filter. Делаем поддержку iframe кодов от Youtube в HTMLPurifier

YoutubeIframe.php

<?php 
#HTMLPurifier/Filter/YoutubeIframe.php

class HTMLPurifier_Filter_YoutubeIframe extends HTMLPurifier_Filter
{
    public $name = 'YouTubeIframe';

    public function preFilter($html, $config, $context) {
        if (strstr($html, '<iframe')) {            
            $html = str_ireplace("</iframe>", "", $html);        
            if (preg_match_all("/<iframe(.*?)>/si", $html, $result)) {                
                foreach ($result[1] as $key => $item) {
                    preg_match('/width="([0-9]+)"/', $item, $width);
                    $width = $width[1];
                    preg_match('/height="([0-9]+)"/', $item, $height);
                    $height = $height[1];
                    preg_match('/https?:\/\/www\.youtube\.com\/embed\/([a-zA-Z0-9_]+)/', $item, $id);
                    $id = $id[1];
                    $html = str_replace($result[0][$key], '<img class="YouTubeIframe" width="'.$width.'" height="'.$height.'" src="http://www.youtube.com/embed/' . $id . '">', $html);                    
                }
            }
        }        
        return $html;
    }

    public function postFilter($html, $config, $context) {
       $post_regex = '#<img class="YouTubeIframe" ([^>]+)>#';
       $html = preg_replace_callback($post_regex, array($this, 'postFilterCallback'), $html);
       return $html;
    }

    protected function postFilterCallback($matches) {
        return '<iframe frameborder="0" allowfullscreen '.$matches[1].'></iframe>';
    }
}