public function asset_url($path)
    {
        // iframe content can't be in a different domain
        // @TODO: check if assests are on a different domain

        if (!$this->assets_path || in_array($path[0], array('?', '/', '.')) || strpos($path, '://')) {
            return $path;
        }

        return $this->assets_path . $path;
    }