/**
  * Return current auth status
  * @return bool
  */
 public static function isAuth()
 {
     if (isset($_COOKIE['remember_key']) && !isset($_SESSION['auth'])) {
         $userModel = new UserModel();
         $user = $userModel->getUserByRememberKey($_COOKIE['remember_key']);
         if ($user) {
             $tmpKey = self::generateRememberKey($user);
             if ($tmpKey === $_COOKIE['remember_key']) {
                 self::doLogin($user);
             }
         } else {
             setcookie('remember_key', null, time(), '/');
         }
     }
     return isset($_SESSION['auth']);
 }