如何在Mobile Angular UI中实现用户认证？

var config = {
  apiKey: "YOUR_API_KEY",
  authDomain: "YOUR_AUTH_DOMAIN",
  databaseURL: "YOUR_DATABASE_URL",
  projectId: "YOUR_PROJECT_ID",
  storageBucket: "YOUR_STORAGE_BUCKET",
  messagingSenderId: "YOUR_MESSAGING_SENDER_ID"
};
firebase.initializeApp(config);

var auth = firebase.auth();

auth.signInWithEmailAndPassword(email, password).then(function(user) {
  // TODO: 处理登录成功
}).catch(function(error) {
  // TODO: 处理登录失败
});

auth.onAuthStateChanged(function(user) {
  if (user) {
    // 用户已登录
  } else {
    // 用户已注销
  }
});