$img = '';
    $src = '';
    $no = $PowerBB->_CONF['info_row']['topic_thump_imgno'];
    $text = str_replace('[youtube]', '[img]', $text);
    $text = str_replace('youtube.com/v/', 'youtube.com/watch?v=', $text);
    $text = str_replace('youtube.com/embed/', 'youtube.com/watch?v=', $text);
    $text = str_replace('youtu.be/', 'youtube.com/watch?v=', $text);
    $text = str_replace('[/youtube]', '[/img]', $text);
    $text = @preg_replace("#[img](([^ nr]+?))[/img]#si", "<img src="\1" />", $text);
    @ preg_match_all("/src=(["'])?((?(1).*?|S+))(?(1)1)/", $text, $images);
    $length = sizeof($images[2]);
    if ($length == 0) {
      $src = '';
    }
    else {
      foreach ($images[2] as $src) {
        $i++;
        if ($no == $i && $length > 1) {
          break;
        }
      }
    }
    $img = $src;
    $invalid_chars = array('&quot;', '#39;', '"', "'", '\');
    $img = str_replace($invalid_chars, '', $img);
    if (stristr($img, 'youtube.com/watch')) {
      $imgA1 = explode('v=', $img);
      $imgA2 = explode('&', $imgA1[1]);
      $img = 'https://i1.ytimg.com/vi/' . $imgA2[0] . '/mqdefault.jpg';
    }
    $filename = @ basename($img);
    $filename = strtolower($filename);
    $temparray = explode(".", $filename);
    $extension = $temparray[count($temparray) - 1];
    $extension = '.' . strtolower($extension);
    if (stristr($img, 'base64,') || stristr($img, '==')) {
      $img = '';
    }
    if (stristr($img, 'smiles')) {
      $img = '';
    }
    if (stristr($img, 'attach.gif')) {
      $img = '';
    }
    $img = strip_tags($img);
    if ($img) {
      $img = $PowerBB->functions->CleanVariable($img, 'trim');
      $img = $PowerBB->functions->CleanVariable($img, 'html');
      $img = $PowerBB->functions->CleanVariable($img, 'sql');
    $img = str_replace('&amp;', '&', $img);
    }