feat(flutter_firebase_login): implement sign in with apple

examples/flutter_firebase_login/README.md

@@ -7,6 +7,7 @@ Example Flutter app built with `flutter_bloc` to implement login using Firebase.
 ## Features
 
 - Sign in with Google
+- Sign in with Apple
 - Sign up with email and password
 - Sign in with email and password
 

examples/flutter_firebase_login/lib/app/bloc_observer.dart

@@ -1,28 +1,29 @@
-// ignore_for_file: avoid_print
+import 'dart:developer';
+
 import 'package:bloc/bloc.dart';
 
 class AppBlocObserver extends BlocObserver {
   @override
   void onEvent(Bloc bloc, Object? event) {
     super.onEvent(bloc, event);
-    print(event);
+    log('event: $event');
   }
 
   @override
   void onError(BlocBase bloc, Object error, StackTrace stackTrace) {
-    print(error);
+    log('error: $error');
     super.onError(bloc, error, stackTrace);
   }
 
   @override
   void onChange(BlocBase bloc, Change change) {
     super.onChange(bloc, change);
-    print(change);
+    log('change: $change');
   }
 
   @override
   void onTransition(Bloc bloc, Transition transition) {
     super.onTransition(bloc, transition);
-    print(transition);
+    log('transition: $transition');
   }
 }

examples/flutter_firebase_login/lib/app/routes/routes.dart

@@ -8,7 +8,6 @@ List<Page> onGenerateAppViewPages(AppStatus state, List<Page<dynamic>> pages) {
     case AppStatus.authenticated:
       return [HomePage.page()];
     case AppStatus.unauthenticated:
-    default:
       return [LoginPage.page()];
   }
 }

examples/flutter_firebase_login/lib/login/cubit/login_cubit.dart

@@ -13,18 +13,22 @@ class LoginCubit extends Cubit<LoginState> {
 
   void emailChanged(String value) {
     final email = Email.dirty(value);
-    emit(state.copyWith(
-      email: email,
-      status: Formz.validate([email, state.password]),
-    ));
+    emit(
+      state.copyWith(
+        email: email,
+        status: Formz.validate([email, state.password]),
+      ),
+    );
   }
 
   void passwordChanged(String value) {
     final password = Password.dirty(value);
-    emit(state.copyWith(
-      password: password,
-      status: Formz.validate([state.email, password]),
-    ));
+    emit(
+      state.copyWith(
+        password: password,
+        status: Formz.validate([state.email, password]),
+      ),
+    );
   }
 
   Future<void> logInWithCredentials() async {
@@ -60,4 +64,17 @@ class LoginCubit extends Cubit<LoginState> {
       emit(state.copyWith(status: FormzStatus.submissionFailure));
     }
   }
+
+  Future<void> logInWithApple() async {
+    emit(state.copyWith(status: FormzStatus.submissionInProgress));
+    try {
+      await _authenticationRepository.logInWithApple();
+      emit(state.copyWith(status: FormzStatus.submissionSuccess));
+    } on Exception {
+      emit(state.copyWith(status: FormzStatus.submissionFailure));
+      // ignore: avoid_catching_errors
+    } on NoSuchMethodError {
+      emit(state.copyWith(status: FormzStatus.pure));
+    }
+  }
 }

examples/flutter_firebase_login/lib/login/view/login_form.dart

@@ -40,6 +40,8 @@ class LoginForm extends StatelessWidget {
               _LoginButton(),
               const SizedBox(height: 8),
               _GoogleLoginButton(),
+              const SizedBox(height: 8),
+              _AppleLoginButton(),
               const SizedBox(height: 4),
               _SignUpButton(),
             ],
@@ -141,6 +143,27 @@ class _GoogleLoginButton extends StatelessWidget {
   }
 }
 
+class _AppleLoginButton extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    return ElevatedButton.icon(
+      key: const Key('loginForm_appleLogin_raisedButton'),
+      label: const Text(
+        'SIGN IN WITH Apple',
+        style: TextStyle(color: Colors.white),
+      ),
+      style: ElevatedButton.styleFrom(
+        shape: RoundedRectangleBorder(
+          borderRadius: BorderRadius.circular(0),
+        ),
+        primary: Colors.black,
+      ),
+      icon: const Icon(FontAwesomeIcons.apple, color: Colors.white),
+      onPressed: () => context.read<LoginCubit>().logInWithApple(),
+    );
+  }
+}
+
 class _SignUpButton extends StatelessWidget {
   @override
   Widget build(BuildContext context) {

examples/flutter_firebase_login/lib/sign_up/cubit/sign_up_cubit.dart

@@ -13,14 +13,16 @@ class SignUpCubit extends Cubit<SignUpState> {
 
   void emailChanged(String value) {
     final email = Email.dirty(value);
-    emit(state.copyWith(
-      email: email,
-      status: Formz.validate([
-        email,
-        state.password,
-        state.confirmedPassword,
-      ]),
-    ));
+    emit(
+      state.copyWith(
+        email: email,
+        status: Formz.validate([
+          email,
+          state.password,
+          state.confirmedPassword,
+        ]),
+      ),
+    );
   }
 
   void passwordChanged(String value) {
@@ -29,30 +31,35 @@ class SignUpCubit extends Cubit<SignUpState> {
       password: password.value,
       value: state.confirmedPassword.value,
     );
-    emit(state.copyWith(
-      password: password,
-      confirmedPassword: confirmedPassword,
-      status: Formz.validate([
-        state.email,
-        password,
-        confirmedPassword,
-      ]),
-    ));
+
+    emit(
+      state.copyWith(
+        password: password,
+        confirmedPassword: confirmedPassword,
+        status: Formz.validate([
+          state.email,
+          password,
+          state.confirmedPassword,
+        ]),
+      ),
+    );
   }
 
   void confirmedPasswordChanged(String value) {
     final confirmedPassword = ConfirmedPassword.dirty(
       password: state.password.value,
       value: value,
     );
-    emit(state.copyWith(
-      confirmedPassword: confirmedPassword,
-      status: Formz.validate([
-        state.email,
-        state.password,
-        confirmedPassword,
-      ]),
-    ));
+    emit(
+      state.copyWith(
+        confirmedPassword: confirmedPassword,
+        status: Formz.validate([
+          state.email,
+          state.password,
+          confirmedPassword,
+        ]),
+      ),
+    );
   }
 
   Future<void> signUpFormSubmitted() async {

examples/flutter_firebase_login/packages/authentication_repository/lib/src/authentication_repository.dart

@@ -2,11 +2,13 @@ import 'dart:async';
 
 import 'package:authentication_repository/authentication_repository.dart';
 import 'package:cache/cache.dart';
+import 'package:crypto_api/crypto_api.dart';
 import 'package:firebase_auth/firebase_auth.dart' as firebase_auth;
 import 'package:firebase_auth_platform_interface/firebase_auth_platform_interface.dart';
 import 'package:flutter/foundation.dart' show kIsWeb;
 import 'package:google_sign_in/google_sign_in.dart';
 import 'package:meta/meta.dart';
+import 'package:sign_in_with_apple/sign_in_with_apple.dart';
 
 /// {@template sign_up_with_email_and_password_failure}
 /// Thrown if during the sign up process if a failure occurs.
@@ -145,6 +147,9 @@ class LogInWithGoogleFailure implements Exception {
   final String message;
 }
 
+/// Thrown during the sign in with apple process if a failure occurs.
+class LogInWithAppleFailure implements Exception {}
+
 /// Thrown during the logout process if a failure occurs.
 class LogOutFailure implements Exception {}
 
@@ -157,13 +162,16 @@ class AuthenticationRepository {
     CacheClient? cache,
     firebase_auth.FirebaseAuth? firebaseAuth,
     GoogleSignIn? googleSignIn,
+    CryptoApi? cryptoApi,
   })  : _cache = cache ?? CacheClient(),
         _firebaseAuth = firebaseAuth ?? firebase_auth.FirebaseAuth.instance,
-        _googleSignIn = googleSignIn ?? GoogleSignIn.standard();
+        _googleSignIn = googleSignIn ?? GoogleSignIn.standard(),
+        _crypto = cryptoApi ?? CryptoApi();
 
   final CacheClient _cache;
   final firebase_auth.FirebaseAuth _firebaseAuth;
   final GoogleSignIn _googleSignIn;
+  final CryptoApi _crypto;
 
   /// Whether or not the current environment is web
   /// Should only be overriden for testing purposes. Otherwise,
@@ -239,6 +247,38 @@ class AuthenticationRepository {
     }
   }
 
+  /// Starts the Sign In with Apple Flow.
+  ///
+  /// Throws a [logInWithApple] if an exception occurs.
+  Future<void> logInWithApple() async {
+    // To prevent replay attacks with the credential returned from Apple, we
+    // include a nonce in the credential request. When signing in with
+    // Firebase, the nonce in the id token returned by Apple, is expected to
+    // match the sha256 hash of `rawNonce`.
+    final rawNonce = _crypto.generateNonce();
+    final nonce = _crypto.sha256ofString(rawNonce);
+
+    try {
+      final appleCredential = await SignInWithApple.getAppleIDCredential(
+        scopes: [
+          AppleIDAuthorizationScopes.email,
+          AppleIDAuthorizationScopes.fullName,
+        ],
+        nonce: nonce,
+      );
+
+      // Create an `OAuthCredential` from the credential returned by Apple.
+      final credential = firebase_auth.OAuthProvider('apple.com').credential(
+        idToken: appleCredential.identityToken,
+        rawNonce: rawNonce,
+      );
+
+      await _firebaseAuth.signInWithCredential(credential);
+    } on Exception {
+      throw LogInWithAppleFailure();
+    }
+  }
+
   /// Signs in with the provided [email] and [password].
   ///
   /// Throws a [LogInWithEmailAndPasswordFailure] if an exception occurs.

examples/flutter_firebase_login/packages/authentication_repository/pubspec.yaml

@@ -9,13 +9,16 @@ environment:
 dependencies:
   cache:
     path: ../cache
+  crypto_api:
+    path: ../crypto_api
   equatable: ^2.0.3
   firebase_auth: ^3.0.2
   firebase_core: ^1.5.0
   flutter:
     sdk: flutter
   google_sign_in: ^5.0.7
   meta: ^1.3.0
+  sign_in_with_apple: ^3.0.0
   very_good_analysis: ^2.3.0
 
 dev_dependencies:

examples/flutter_firebase_login/packages/authentication_repository/test/models/user_test.dart

@@ -10,7 +10,7 @@ void main() {
     test('uses value equality', () {
       expect(
         User(email: email, id: id),
-        equals(User(email: email, id: id)),
+        User(email: email, id: id),
       );
     });
 

examples/flutter_firebase_login/packages/cache/pubspec.yaml

@@ -1,5 +1,5 @@
 name: cache
-description: A simple in memory cache made for dart
+description: A simple in memory cache made for Dart.
 version: 1.0.0
 publish_to: none
 

examples/flutter_firebase_login/packages/crypto_api/analysis_options.yaml

@@ -0,0 +1 @@
+include: package:very_good_analysis/analysis_options.2.3.0.yaml

examples/flutter_firebase_login/packages/crypto_api/lib/crypto_api.dart

@@ -0,0 +1,36 @@
+library crypto_api;
+
+import 'dart:convert';
+import 'dart:math';
+
+import 'package:crypto/crypto.dart';
+
+/// {@template crypto_api}
+/// A crypto API with common encryption methods.
+/// {@endtemplate}
+class CryptoApi {
+  /// {@macro crypto_api}
+  CryptoApi({Random? random}) : _random = random ?? Random.secure();
+
+  final Random _random;
+
+  /// Set of characters used to generate encrypted values.
+  static const _charset =
+      '''0123456789ABCDEFGHIJKLMNOPQRSTUVXYZabcdefghijklmnopqrstuvwxyz-._''';
+
+  /// Generates a cryptographically secure random nonce,
+  /// to be included in a credential request.
+  String generateNonce([int length = 32]) {
+    return List.generate(
+      length,
+      (_) => _charset[_random.nextInt(_charset.length)],
+    ).join();
+  }
+
+  /// Returns the sha256 hash of [input] in hex notation.
+  String sha256ofString(String input) {
+    final bytes = utf8.encode(input);
+    final digest = sha256.convert(bytes);
+    return digest.toString();
+  }
+}

examples/flutter_firebase_login/packages/crypto_api/pubspec.yaml

@@ -0,0 +1,14 @@
+name: crypto_api
+description: A crypto API with common encryption methods.
+version: 1.0.0
+publish_to: none
+
+environment:
+  sdk: ">=2.13.0 <3.0.0"
+
+dependencies:
+  crypto: ^3.0.1
+
+dev_dependencies:
+  test: ^1.17.11
+  very_good_analysis: ^2.3.0

examples/flutter_firebase_login/packages/crypto_api/test/crypto_api_test.dart

@@ -0,0 +1,12 @@
+import 'package:crypto_api/crypto_api.dart';
+import 'package:test/test.dart';
+
+void main() {
+  group('CryptoApi', () {
+    test('instanciates', () {
+      test('can be instantiated', () {
+        expect(CryptoApi(), isNotNull);
+      });
+    });
+  });
+}