public static function coverThumb($url, $cover_id) { if ($url) { $base_url = UserUrl::cover(true); return $base_url . '/' . $cover_id . '/' . 'thumb'; } else { $base_path = UserUrl::cover(false); return UserUrl::createNonexistentDirInPath($base_path, $cover_id . DIRECTORY_SEPARATOR . 'thumb'); } }