private function getInterface($class) {
        $interfaceName = $class;
        $interfaces = class_implements($class);
        if (!empty($interfaces)) {
            if (count($interfaces) == 1) {
                $interfaceName = array_shift($interfaces);
            } elseif ($key = array_search($class . 'Interface', $interfaces)) {
                $interfaceName = $interfaces[$key];
            }
        }

        return $interfaceName;
    }