页面重新加载后,如何获取CurrentUser?

以下是我目前的做法:

angular
  .module('mean-starter')
  .factory('Auth', function($http, $state, $window, $cookies) {
    var currentUser = {};

    return {
      signup: function(user) {
        return $http
          .post('/users', user)
          .then(function(data, status, headers, config) {
            angular.copy(data, currentUser);
            $cookies.put('userId', data._id);
            $window.location.href = '/';
          })
        ;
      },
      login: function(user) {
        return $http
          .post('/login', user)
          .then(function(data) {
            angular.copy(data, currentUser);
            $cookies.put('userId', data._id);
            $window.location.href = '/';
          })
        ;
      },
      logout: function() {
        $http
          .get('/logout')
          .then(function() {
            angular.copy({}, currentUser);
            $cookies.remove('userId');
            $window.location.href = '/';
          })
          .catch(function() {
            console.log('Problem logging out.');
          })
        ;
      },
      getCurrentUser: function() {
        // user is logged in
        if (currentUser._id) {
          return currentUser;
        }
        // user is logged in, but page has been refreshed and currentUser is lost
        if ($cookies.get('userId')) {
          return $http.get('/current-user')
            .then(function(data) {
              angular.copy(data, currentUser);
            })
          ;
        }
        // user isn't logged in
        else {
          return currentUser;
        }
      },
      isLoggedIn: function() {
        return !!currentUser._id;
      }
    };
  })
;

重新加载页面后,Auth工厂将重新运行 currentUser 已重新分配给 {} 因此,如果用户登录, 当前用户 不会反映出来。所以我要检查一下 !currentUser._id && $cookies.get('userId') 如果是,则为当前登录的用户查询数据库。

现在我想访问 当前用户 :

angular
  .module('mean-starter')
  .run(run)
;

function run($rootScope, Auth, $state) {
  $rootScope.$on('$stateChangeStart', function(event, toState, toParams) {
    if (typeof toState.authenticate !== 'undefined') {
      var currentUser = Auth.getCurrentUser();
      var admin = currentUser.role === 'admin';
      var authorized = currentUser._id.toString() === toParams.id;
      if (!Auth.isLoggedIn()) {
        event.preventDefault();
        alert('Must be logged in to access this route.');
        $state.go('login');
      }
      else if (toState.authenticate.authorized) {
        if (!admin && !authorized) {
          event.preventDefault();
          alert('You are not authorized to access that route.');
        }
      }
      else if (toState.authenticate.isAdmin) {
        if (!admin) {
          event.preventDefault();
          alert('You must be an admin to access this route.');
        }
      }
    }
  });
}

问题是我不知道是否 Auth.getCurrentUser() 将返回用户或承诺。我该如何检查?这应该如何构建?