feat(ui): Add support for configuring authentication providers global…

…ly (additionally fixes #7801) (#8120)

Co-authored-by: Mike Diarmid <mike.diarmid@gmail.com>

docs/ui/auth/integrating-your-first-screen.mdx

@@ -492,6 +492,65 @@ return ProfileScreen(
   style={{ maxHeight: 700 }}
 />
 
+## Configuring auth providers globally
+
+Instead of passing a list of providers to each screen, you can alternatively provide a list of provider configurations to the `FlutterFireUIAuth.configureProviders` method:
+
+```dart
+Future<void> main() async {
+  // Firebase app should be initialized before calling configureProviders
+  await Firebase.initializeApp();
+
+  FlutterFireUIAuth.configureProviders([
+    const EmailProviderConfiguration(),
+    const PhoneProviderConfiguration(),
+    const GoogleProviderConfiguration(clientId: GOOGLE_CLIENT_ID),
+    const AppleProviderConfiguration(),
+    const FacebookProviderConfiguration(clientId: FACEBOOK_CLIENT_ID),
+    const TwitterProviderConfiguration(
+      apiKey: TWITTER_API_KEY,
+      apiSecretKey: TWITTER_API_SECRET_KEY,
+      redirectUri: TWITTER_REDIRECT_URI,
+    ),
+  ]);
+
+  runApp(MyApp());
+}
+
+class MyApp extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    final auth = FirebaseAuth.instance;
+
+    return MaterialApp(
+      initialRoute: auth.currentUser == null ? '/' : '/profile',
+      routes: {
+        '/': (context) {
+          return SignInScreen(
+            // no providerConfigs property - global configuration will be used instead
+            actions: [
+              AuthStateChangeAction<SignedIn>((context, state) {
+                Navigator.pushReplacementNamed(context, '/profile');
+              }),
+            ],
+          );
+        },
+        '/profile': (context) {
+          return ProfileScreen(
+            // no providerConfigs property here as well
+            actions: [
+              SignedOutAction((context) {
+                Navigator.pushReplacementNamed(context, '/');
+              }),
+            ],
+          );
+        },
+      },
+    );
+  }
+}
+```
+
 ## Next Steps
 
 With your first screen integrated, you can now start adding more providers and integrating more screens!

packages/flutterfire_ui/example/lib/main.dart

@@ -10,9 +10,35 @@ import 'init.dart'
 import 'config.dart';
 import 'decorations.dart';
 
+final emailLinkProviderConfig = EmailLinkProviderConfiguration(
+  actionCodeSettings: ActionCodeSettings(
+    url: 'https://reactnativefirebase.page.link',
+    handleCodeInApp: true,
+    androidMinimumVersion: '12',
+    androidPackageName:
+        'io.flutter.plugins.flutterfire_ui.flutterfire_ui_example',
+    iOSBundleId: 'io.flutter.plugins.flutterfireui.flutterfireUIExample',
+  ),
+);
+
 Future<void> main() async {
   WidgetsFlutterBinding.ensureInitialized();
   await initializeFirebase();
+
+  FlutterFireUIAuth.configureProviders([
+    const EmailProviderConfiguration(),
+    emailLinkProviderConfig,
+    const PhoneProviderConfiguration(),
+    const GoogleProviderConfiguration(clientId: GOOGLE_CLIENT_ID),
+    const AppleProviderConfiguration(),
+    const FacebookProviderConfiguration(clientId: FACEBOOK_CLIENT_ID),
+    const TwitterProviderConfiguration(
+      apiKey: TWITTER_API_KEY,
+      apiSecretKey: TWITTER_API_SECRET_KEY,
+      redirectUri: TWITTER_REDIRECT_URI,
+    ),
+  ]);
+
   runApp(FirebaseAuthUIExample());
 }
 
@@ -26,31 +52,6 @@ class LabelOverrides extends DefaultLocalizations {
   String get emailInputLabel => 'Enter your email';
 }
 
-final emailLinkProviderConfig = EmailLinkProviderConfiguration(
-  actionCodeSettings: ActionCodeSettings(
-    url: 'https://reactnativefirebase.page.link',
-    handleCodeInApp: true,
-    androidMinimumVersion: '12',
-    androidPackageName:
-        'io.flutter.plugins.flutterfire_ui.flutterfire_ui_example',
-    iOSBundleId: 'io.flutter.plugins.flutterfireui.flutterfireUIExample',
-  ),
-);
-
-final providerConfigs = [
-  const EmailProviderConfiguration(),
-  emailLinkProviderConfig,
-  const PhoneProviderConfiguration(),
-  const GoogleProviderConfiguration(clientId: GOOGLE_CLIENT_ID),
-  const AppleProviderConfiguration(),
-  const FacebookProviderConfiguration(clientId: FACEBOOK_CLIENT_ID),
-  const TwitterProviderConfiguration(
-    apiKey: TWITTER_API_KEY,
-    apiSecretKey: TWITTER_API_SECRET_KEY,
-    redirectUri: TWITTER_REDIRECT_URI,
-  ),
-];
-
 class FirebaseAuthUIExample extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
@@ -111,7 +112,6 @@ class FirebaseAuthUIExample extends StatelessWidget {
                 ),
               );
             },
-            providerConfigs: providerConfigs,
           );
         },
         '/phone': (context) {
@@ -150,7 +150,6 @@ class FirebaseAuthUIExample extends StatelessWidget {
         },
         '/profile': (context) {
           return ProfileScreen(
-            providerConfigs: providerConfigs,
             actions: [
               SignedOutAction((context) {
                 Navigator.pushReplacementNamed(context, '/');

packages/flutterfire_ui/lib/auth.dart

@@ -91,3 +91,68 @@ export 'src/auth/configs/phone_provider_configuration.dart';
 export 'src/auth/configs/oauth_provider_configuration.dart';
 export 'src/auth/configs/email_link_provider_configuration.dart';
 export 'src/auth/configs/provider_configuration.dart';
+
+import 'package:firebase_auth/firebase_auth.dart';
+import 'package:firebase_core/firebase_core.dart';
+import 'package:flutter/widgets.dart';
+import 'package:flutterfire_ui/src/auth/actions.dart';
+import 'package:flutterfire_ui/src/auth/configs/oauth_provider_configuration.dart';
+import 'package:flutterfire_ui/src/auth/oauth/oauth_providers.dart';
+
+import 'auth.dart' show ProviderConfiguration;
+
+class FlutterFireUIAuth {
+  static final _configs = <FirebaseApp, List<ProviderConfiguration>>{};
+  static final _configuredApps = <FirebaseApp, bool>{};
+
+  static List<ProviderConfiguration> configsFor(FirebaseApp app) {
+    return _configs[app] ?? [];
+  }
+
+  static bool isAppConfigured(FirebaseApp app) {
+    return _configs.containsKey(app);
+  }
+
+  static void configureProviders(
+    List<ProviderConfiguration> configs, {
+    FirebaseApp? app,
+  }) {
+    if (Firebase.apps.isEmpty) {
+      throw Exception(
+        'You must call Firebase.initializeApp() '
+        'before calling configureProviders()',
+      );
+    }
+
+    final _app = app ?? Firebase.app();
+
+    if (_configuredApps[_app] ?? false) {
+      throw Exception(
+        'You can only configure providers once '
+        'for each Firebase App',
+      );
+    }
+
+    _configs[_app] = configs;
+
+    configs.whereType<OAuthProviderConfiguration>().forEach((element) {
+      final provider = element.createProvider();
+      final auth = FirebaseAuth.instanceFor(app: _app);
+      OAuthProviders.register(auth, provider);
+    });
+  }
+
+  static Future<void> signOut({
+    BuildContext? context,
+    FirebaseAuth? auth,
+  }) async {
+    final _auth = auth ?? FirebaseAuth.instance;
+    await OAuthProviders.signOut(_auth);
+    await _auth.signOut();
+
+    if (context != null) {
+      final action = FlutterFireUIAction.ofType<SignedOutAction>(context);
+      action?.callback(context);
+    }
+  }
+}

packages/flutterfire_ui/lib/src/auth/configs/oauth_provider_configuration.dart

@@ -10,9 +10,12 @@ import '../widgets/internal/oauth_provider_button_style.dart';
 
 import '../flows/oauth_flow.dart';
 
-abstract class OAuthProviderConfiguration extends ProviderConfiguration {
+abstract class OAuthProviderConfiguration<T extends OAuthProvider>
+    extends ProviderConfiguration {
   const OAuthProviderConfiguration();
 
+  Type get providerType => T;
+
   String get defaultRedirectUri =>
       'https://${Firebase.apps.first.options.projectId}.firebaseapp.com/__/auth/handler';
 
@@ -27,7 +30,7 @@ abstract class OAuthProviderConfiguration extends ProviderConfiguration {
     );
   }
 
-  OAuthProvider createProvider();
+  T createProvider();
 
   String getLabel(FlutterFireUILocalizationLabels labels);
 }

packages/flutterfire_ui/lib/src/auth/flows/oauth_flow.dart

@@ -22,7 +22,12 @@ class OAuthFlow extends AuthFlow implements OAuthController {
 
   @override
   Future<void> signInWithProvider(TargetPlatform platform) async {
-    final provider = config.createProvider();
+    OAuthProvider? provider = OAuthProviders.resolve(auth, config.providerType);
+
+    if (provider == null) {
+      provider = config.createProvider();
+      OAuthProviders.register(auth, provider);
+    }
 
     try {
       value = const SigningIn();

packages/flutterfire_ui/lib/src/auth/oauth/oauth_providers.dart

@@ -1,5 +1,53 @@
 import 'package:desktop_webview_auth/desktop_webview_auth.dart';
 import 'package:firebase_auth/firebase_auth.dart';
+import 'package:flutter/widgets.dart';
+
+@immutable
+class ProviderKey {
+  final FirebaseAuth auth;
+  final Type providerType;
+
+  ProviderKey(this.auth, this.providerType);
+
+  @override
+  int get hashCode => hashValues(auth, providerType);
+
+  @override
+  bool operator ==(Object other) {
+    return hashCode == other.hashCode;
+  }
+}
+
+abstract class OAuthProviders {
+  static final _providers = <ProviderKey, OAuthProvider>{};
+
+  static void register(FirebaseAuth? auth, OAuthProvider provider) {
+    final _auth = auth ?? FirebaseAuth.instance;
+    final key = ProviderKey(_auth, provider.runtimeType);
+
+    _providers[key] = provider;
+  }
+
+  static OAuthProvider? resolve(FirebaseAuth? auth, Type providerType) {
+    final _auth = auth ?? FirebaseAuth.instance;
+    final key = ProviderKey(_auth, providerType);
+    return _providers[key];
+  }
+
+  static Iterable<OAuthProvider> providersFor(FirebaseAuth auth) sync* {
+    for (final k in _providers.keys) {
+      if (k.auth == auth) {
+        yield _providers[k]!;
+      }
+    }
+  }
+
+  static Future<void> signOut([FirebaseAuth? auth]) async {
+    final _auth = auth ?? FirebaseAuth.instance;
+    final futures = providersFor(_auth).map((e) => e.signOut());
+    await Future.wait(futures);
+  }
+}
 
 abstract class OAuthProvider {
   Future<OAuthCredential> signIn();
@@ -19,9 +67,7 @@ abstract class OAuthProvider {
     return credential;
   }
 
-  Future<void> signOut() async {
-    await FirebaseAuth.instance.signOut();
-  }
+  Future<void> signOut() async {}
 }
 
 extension OAuthHelpers on User {

packages/flutterfire_ui/lib/src/auth/oauth/providers/apple_provider.dart

@@ -31,7 +31,9 @@ String sha256ofString(String input) {
   return digest.toString();
 }
 
-class AppleProviderImpl extends OAuthProvider {
+abstract class AppleProvider extends OAuthProvider {}
+
+class AppleProviderImpl extends AppleProvider {
   @override
   Future<fba.OAuthCredential> signIn() async {
     final rawNonce = generateNonce();
@@ -72,11 +74,12 @@ class AppleProviderImpl extends OAuthProvider {
   dynamic get firebaseAuthProvider => null;
 }
 
-class AppleProviderConfiguration extends OAuthProviderConfiguration {
+class AppleProviderConfiguration
+    extends OAuthProviderConfiguration<AppleProvider> {
   const AppleProviderConfiguration();
 
   @override
-  OAuthProvider createProvider() {
+  AppleProvider createProvider() {
     return AppleProviderImpl();
   }
 

packages/flutterfire_ui/lib/src/auth/oauth/providers/facebook_provider.dart

@@ -12,7 +12,9 @@ import '../../oauth/provider_resolvers.dart';
 import '../../auth_flow.dart';
 import '../oauth_providers.dart';
 
-class FacebookProviderImpl extends OAuthProvider {
+abstract class FacebookProvider extends OAuthProvider {}
+
+class FacebookProviderImpl extends FacebookProvider {
   final _provider = FacebookAuth.instance;
   final String clientId;
   final String redirectUri;
@@ -47,6 +49,11 @@ class FacebookProviderImpl extends OAuthProvider {
     }
   }
 
+  @override
+  Future<void> signOut() async {
+    await _provider.logOut();
+  }
+
   @override
   OAuthCredential fromDesktopAuthResult(AuthResult result) {
     return FacebookAuthProvider.credential(result.accessToken!);
@@ -56,7 +63,8 @@ class FacebookProviderImpl extends OAuthProvider {
   FacebookAuthProvider get firebaseAuthProvider => FacebookAuthProvider();
 }
 
-class FacebookProviderConfiguration extends OAuthProviderConfiguration {
+class FacebookProviderConfiguration
+    extends OAuthProviderConfiguration<FacebookProvider> {
   final String clientId;
   final String? redirectUri;
 
@@ -65,7 +73,7 @@ class FacebookProviderConfiguration extends OAuthProviderConfiguration {
     this.redirectUri,
   });
 
-  OAuthProvider get _provider => FacebookProviderImpl(
+  FacebookProvider get _provider => FacebookProviderImpl(
         clientId: clientId,
         redirectUri: redirectUri ?? defaultRedirectUri,
       );
@@ -74,7 +82,7 @@ class FacebookProviderConfiguration extends OAuthProviderConfiguration {
   String get providerId => FACEBOOK_PROVIDER_ID;
 
   @override
-  OAuthProvider createProvider() {
+  FacebookProvider createProvider() {
     return _provider;
   }