firebase-auth.html

<!--
@license
Copyright 2016 Google Inc. All Rights Reserved.
Use of this source code is governed by a BSD-style
license that can be found in the LICENSE file or at
https://github.com/firebase/polymerfire/blob/master/LICENSE
-->

<link rel="import" href="../polymer/polymer.html">
<link rel="import" href="firebase.html">
<link rel="import" href="firebase-common-behavior.html">

<!--
`firebase-auth` is a wrapper around the Firebase authentication API. It notifies
successful authentication, provides user information, and handles different
types of authentication including anonymous, email / password, and several OAuth
workflows.

Example Usage:
```html
<firebase-app auth-domain="polymerfire-test.firebaseapp.com"
  database-url="https://polymerfire-test.firebaseio.com/"
  api-key="AIzaSyDTP-eiQezleFsV2WddFBAhF_WEzx_8v_g">
</firebase-app>
<firebase-auth id="auth" user="{{user}}" provider="google" on-error="handleError">
</firebase-auth>
```

The `firebase-app` element initializes `app` in `firebase-auth` (see
`firebase-app` documentation for more information), but an app name can simply
be specified at `firebase-auth`'s `app-name` property instead.

JavaScript sign-in calls can then be made to the `firebase-auth` object to
attempt authentication, e.g.:

```javascript
this.$.signInWithPopup()
    .then(function(response) {// successful authentication response here})
    .catch(function(error) {// unsuccessful authentication response here});
```

This popup sign-in will then attempt to sign in using Google as an OAuth
provider since there was no provider argument specified and since `"google"` was
defined as the default provider.
-->
<dom-module id="firebase-auth">
  <script>
    (function() {
      'use strict';

      Polymer({

        is: 'firebase-auth',

        behaviors: [
          Polymer.FirebaseCommonBehavior
        ],

        properties: {
          /**
           * [`firebase.Auth`](https://firebase.google.com/docs/reference/js/firebase.auth.Auth) service interface.
           */
          auth: {
            type: Object,
            computed: '_computeAuth(app)',
            observer: '__authChanged'
          },

          /**
           * Default auth provider OAuth flow to use when attempting provider
           * sign in. This property can remain undefined when attempting to sign
           * in anonymously, using email and password, or when specifying a
           * provider in the provider sign-in function calls (i.e.
           * `signInWithPopup` and `signInWithRedirect`).
           *
           * Current accepted providers are:
           *
           * ```
           * 'facebook'
           * 'github'
           * 'google'
           * 'twitter'
           * ```
           */
          provider: {
            type: String,
            notify: true
          },

          /**
           * True if the client is authenticated, and false if the client is not
           * authenticated.
           */
          signedIn: {
            type: Boolean,
            computed: '_computeSignedIn(user)',
            notify: true
          },

          /**
           * The currently-authenticated user with user-related metadata. See
           * the [`firebase.User`](https://firebase.google.com/docs/reference/js/firebase.User)
           * documentation for the spec.
           */
          user: {
            type: Object,
            readOnly: true,
            value: null,
            notify: true
          }
        },

        /**
         * Authenticates a Firebase client using a new, temporary guest account.
         *
         * @return {Promise} Promise that handles success and failure.
         */
        signInAnonymously: function() {
          if (!this.auth) {
            return Promise.reject('No app configured for firebase-auth!');
          }

          return this._handleSignIn(this.auth.signInAnonymously());
        },

        /**
         * Authenticates a Firebase client using a popup-based OAuth flow.
         *
         * @param  {?String} provider Provider OAuth flow to follow. If no
         * provider is specified, it will default to the element's `provider`
         * property's OAuth flow (See the `provider` property's documentation
         * for supported providers).
         * @return {Promise} Promise that handles success and failure.
         */
        signInWithPopup: function(provider) {
          return this._attemptProviderSignIn(provider, this.auth.signInWithPopup);
        },

        /**
         * Authenticates a firebase client using a redirect-based OAuth flow.
         *
         * @param  {?String} provider Provider OAuth flow to follow. If no
         * provider is specified, it will default to the element's `provider`
         * property's OAuth flow (See the `provider` property's documentation
         * for supported providers).
         * @return {Promise} Promise that handles failure. (NOTE: The Promise
         * will not get resolved on success due to the inherent page redirect
         * of the auth flow, but it can be used to handle errors that happen
         * before the redirect).
         */
        signInWithRedirect: function(provider) {
          return this._attemptProviderSignIn(provider, this.auth.signInWithRedirect);
        },

        /**
         * Authenticates a Firebase client using an email / password combination.
         *
         * @param  {!String} email Email address corresponding to the user account.
         * @param  {!String} password Password corresponding to the user account.
         * @return {Promise} Promise that handles success and failure.
         */
        signInWithEmailAndPassword: function(email, password) {
          return this._handleSignIn(this.auth.signInWithEmailAndPassword(email, password));
        },

        /**
         * Creates a new user account using an email / password combination.
         *
         * @param  {!String} email Email address corresponding to the user account.
         * @param  {!String} password Password corresponding to the user account.
         * @return {Promise} Promise that handles success and failure.
         */
        createUserWithEmailAndPassword: function(email, password) {
          return this._handleSignIn(this.auth.createUserWithEmailAndPassword(email, password));
        },

        /**
         * Unauthenticates a Firebase client.
         *
         * @return {Promise} Promise that handles success and failure.
         */
        signOut: function() {
          if (!this.auth) {
            return Promise.reject('No app configured for auth!');
          }

          return this.auth.signOut();
        },

        _attemptProviderSignIn: function(provider, method) {
          provider = provider || this._providerFromName(this.provider);
          if (!provider) {
            return Promise.reject('Must supply a provider for popup sign in.');
          }
          if (!this.auth) {
            return Promise.reject('No app configured for firebase-auth!');
          }

          return this._handleSignIn(method.call(this.auth, provider));
        },

        _providerFromName: function(name) {
          switch (name) {
            case 'facebook': return new firebase.auth.FacebookAuthProvider();
            case 'github': return new firebase.auth.GithubAuthProvider();
            case 'google': return new firebase.auth.GoogleAuthProvider();
            case 'twitter': return new firebase.auth.TwitterAuthProvider();
            default: this.fire('error', 'Unrecognized firebase-auth provider "' + name + '"');
          }
        },

        _handleSignIn: function(promise) {
          return promise.catch(function(err) {
            this.fire('error', err);
            throw err;
          }.bind(this));
        },

        _computeSignedIn: function(user) {
          return !!user;
        },

        _computeAuth: function(app) {
          return this.app.auth();
        },

        __authChanged: function(auth, oldAuth) {
          if (oldAuth !== auth && this._unsubscribe) {
            this._unsubscribe();
            this._unsubscribe = null;
          }

          if (this.auth) {
            this._unsubscribe = this.auth.onAuthStateChanged(function(user) {
              this._setUser(user);
            }.bind(this), function(err) {
              this.fire('error', err);
            }.bind(this));
          }
        }
      });
    })();
  </script>
</dom-module>