// Copyright 2017 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import 'dart:async';

import 'package:flutter/services.dart';
import 'package:meta/meta.dart';

/// Represents user data returned from an identity provider.
class UserInfo {
  final Map<String, dynamic> _data;

  UserInfo._(this._data);

  /// The provider identifier.
  String get providerId => _data['providerId'];

  /// The provider’s user ID for the user.
  String get uid => _data['uid'];

  /// The name of the user.
  String get displayName => _data['displayName'];

  /// The URL of the user’s profile photo.
  String get photoUrl => _data['photoUrl'];

  /// The user’s email address.
  String get email => _data['email'];

  @override
  String toString() {
    return '$runtimeType($_data)';
  }
}

/// Represents a user.
class FirebaseUser extends UserInfo {
  final List<UserInfo> providerData;

  FirebaseUser._(Map<String, dynamic> data)
      : providerData = data['providerData']
            .map((Map<String, dynamic> info) => new UserInfo._(info))
            .toList(),
        super._(data);

  // Returns true if the user is anonymous; that is, the user account was
  // created with signInAnonymously() and has not been linked to another
  // account.
  bool get isAnonymous => _data['isAnonymous'];

  /// Returns true if the user's email is verified.
  bool get isEmailVerified => _data['isEmailVerified'];

  /// Obtains the id token for the current user, forcing a [refresh] if desired.
  ///
  /// Completes with an error if the user is signed out.
  Future<String> getIdToken({bool refresh: false}) {
    return FirebaseAuth.channel.invokeMethod('getIdToken', <String, bool>{
      'refresh': refresh,
    });
  }

  @override
  String toString() {
    return '$runtimeType($_data)';
  }
}

class FirebaseAuth {
  @visibleForTesting
  static const MethodChannel channel = const MethodChannel(
    'plugins.flutter.io/firebase_auth',
  );

  final Map<int, StreamController<FirebaseUser>> _authStateChangedControllers =
      <int, StreamController<FirebaseUser>>{};

  /// Provides an instance of this class corresponding to the default app.
  ///
  /// TODO(jackson): Support for non-default apps.
  static FirebaseAuth instance = new FirebaseAuth._();

  FirebaseAuth._() {
    channel.setMethodCallHandler(_callHandler);
  }

  /// Receive [FirebaseUser] each time the user signIn or signOut
  Stream<FirebaseUser> get onAuthStateChanged {
    Future<int> _handle;

    StreamController<FirebaseUser> controller;
    controller = new StreamController<FirebaseUser>.broadcast(onListen: () {
      _handle = channel.invokeMethod('startListeningAuthState');
      _handle.then((int handle) {
        _authStateChangedControllers[handle] = controller;
      });
    }, onCancel: () {
      _handle.then((int handle) async {
        await channel.invokeMethod(
            "stopListeningAuthState", <String, int>{"id": handle});
        _authStateChangedControllers.remove(handle);
      });
    });

    return controller.stream;
  }

  /// Asynchronously creates and becomes an anonymous user.
  ///
  /// If there is already an anonymous user signed in, that user will be
  /// returned instead. If there is any other existing user signed in, that
  /// user will be signed out.
  ///
  /// Will throw a PlatformException if
  /// FIRAuthErrorCodeOperationNotAllowed - Indicates that anonymous accounts are not enabled. Enable them in the Auth section of the Firebase console.
  /// See FIRAuthErrors for a list of error codes that are common to all API methods.
  Future<FirebaseUser> signInAnonymously() async {
    final Map<String, dynamic> data =
        await channel.invokeMethod('signInAnonymously');
    final FirebaseUser currentUser = new FirebaseUser._(data);
    return currentUser;
  }

  Future<FirebaseUser> createUserWithEmailAndPassword({
    @required String email,
    @required String password,
  }) async {
    assert(email != null);
    assert(password != null);
    final Map<String, dynamic> data = await channel.invokeMethod(
      'createUserWithEmailAndPassword',
      <String, String>{
        'email': email,
        'password': password,
      },
    );
    final FirebaseUser currentUser = new FirebaseUser._(data);
    return currentUser;
  }

  Future<FirebaseUser> signInWithEmailAndPassword({
    @required String email,
    @required String password,
  }) async {
    assert(email != null);
    assert(password != null);
    final Map<String, dynamic> data = await channel.invokeMethod(
      'signInWithEmailAndPassword',
      <String, String>{
        'email': email,
        'password': password,
      },
    );
    final FirebaseUser currentUser = new FirebaseUser._(data);
    return currentUser;
  }

  Future<FirebaseUser> signInWithFacebook(
      {@required String accessToken}) async {
    assert(accessToken != null);
    final Map<String, dynamic> data =
        await channel.invokeMethod('signInWithFacebook', <String, String>{
      'accessToken': accessToken,
    });
    final FirebaseUser currentUser = new FirebaseUser._(data);
    return currentUser;
  }

  Future<FirebaseUser> signInWithGoogle({
    @required String idToken,
    @required String accessToken,
  }) async {
    assert(idToken != null);
    assert(accessToken != null);
    final Map<String, dynamic> data = await channel.invokeMethod(
      'signInWithGoogle',
      <String, String>{
        'idToken': idToken,
        'accessToken': accessToken,
      },
    );
    final FirebaseUser currentUser = new FirebaseUser._(data);
    return currentUser;
  }

  Future<FirebaseUser> signInWithCustomToken({@required String token}) async {
    assert(token != null);
    final Map<String, dynamic> data = await channel.invokeMethod(
      'signInWithCustomToken',
      <String, String>{
        'token': token,
      },
    );
    final FirebaseUser currentUser = new FirebaseUser._(data);
    return currentUser;
  }

  Future<Null> signOut() async {
    return await channel.invokeMethod("signOut");
  }

  /// Asynchronously gets current user, or `null` if there is none.
  Future<FirebaseUser> currentUser() async {
    final Map<String, dynamic> data = await channel.invokeMethod("currentUser");
    final FirebaseUser currentUser =
        data == null ? null : new FirebaseUser._(data);
    return currentUser;
  }

  /// Links email account with current user and returns [Future<FirebaseUser>]
  /// basically current user with addtional email infomation
  ///
  /// throws [PlatformException] when
  /// 1. email address is already used
  /// 2. wrong email and password provided
  Future<FirebaseUser> linkWithEmailAndPassword({
    @required String email,
    @required String password,
  }) async {
    assert(email != null);
    assert(password != null);
    final Map<String, dynamic> data = await channel.invokeMethod(
      'linkWithEmailAndPassword',
      <String, String>{
        'email': email,
        'password': password,
      },
    );
    final FirebaseUser currentUser = new FirebaseUser._(data);
    return currentUser;
  }

  /// Links google account with current user and returns [Future<FirebaseUser>]
  ///
  /// throws [PlatformException] when
  /// 1. No current user provided (user has not logged in)
  /// 2. No google credentials were found for given [idToken] and [accessToken]
  /// 3. Google account already linked with another [FirebaseUser]
  /// Detailed documentation on possible error causes can be found in [Android docs](https://firebase.google.com/docs/reference/android/com/google/firebase/auth/FirebaseUser#exceptions_4) and [iOS docs](https://firebase.google.com/docs/reference/ios/firebaseauth/api/reference/Classes/FIRUser#/c:objc(cs)FIRUser(im)linkWithCredential:completion:)
  /// TODO: Throw custom exceptions with error codes indicating cause of exception
  Future<FirebaseUser> linkWithGoogleCredential({
    @required String idToken,
    @required String accessToken,
  }) async {
    assert(idToken != null);
    assert(accessToken != null);
    final Map<String, dynamic> data = await channel.invokeMethod(
      'linkWithGoogleCredential',
      <String, String>{
        'idToken': idToken,
        'accessToken': accessToken,
      },
    );
    final FirebaseUser currentUser = new FirebaseUser._(data);
    return currentUser;
  }

  Future<Null> _callHandler(MethodCall call) async {
    switch (call.method) {
      case "onAuthStateChanged":
        _onAuthStageChangedHandler(call);
        break;
    }
    return null;
  }

  void _onAuthStageChangedHandler(MethodCall call) {
    final Map<String, dynamic> data = call.arguments["user"];
    final int id = call.arguments["id"];

    final FirebaseUser currentUser =
        data != null ? new FirebaseUser._(data) : null;
    _authStateChangedControllers[id].add(currentUser);
  }
}