[google_sign_in] Support Dart-only configuration

Author: blaugold

packages/google_sign_in/google_sign_in/CHANGELOG.md

@@ -1,3 +1,7 @@
+## Next
+
+* Add support for configuring `serverClientId` through `GoogleSignIn` constructor.
+
 ## 5.3.0
 
 * Moves Android and iOS implementations to federated packages.

packages/google_sign_in/google_sign_in/README.md

@@ -65,6 +65,20 @@ This plugin requires iOS 9.0 or higher.
 <!-- End of the Google Sign-in Section -->
 ```
 
+Instead of adding `GoogleService-Info.plist` to your Xcode project, you can configure your app in
+Dart code. In this case, skip steps 3-6 and pass `clientId` and `serverClientId` to the
+`GoogleSignIn` constructor:
+
+```dart
+GoogleSignIn _googleSignIn = GoogleSignIn(
+  ...
+  // Copied from GoogleService-Info.plist key CLIENT_ID
+  clientId: '861823949799-vc35cprkp249096uujjn0vvnmcvjppkn.apps.googleusercontent.com',
+  // Copied from GoogleService-Info.plist key SERVER_CLIENT_ID
+  serverClientId: 'YOUR_SERVER_CLIENT_ID',
+);
+```
+
 #### iOS additional requirement
 
 Note that according to

packages/google_sign_in/google_sign_in/lib/google_sign_in.dart

@@ -183,6 +183,7 @@ class GoogleSignIn {
     this.scopes = const <String>[],
     this.hostedDomain,
     this.clientId,
+    this.serverClientId,
   });
 
   /// Factory for creating default sign in user experience.
@@ -228,9 +229,14 @@ class GoogleSignIn {
   /// Domain to restrict sign-in to.
   final String? hostedDomain;
 
-  /// Client ID being used to connect to google sign-in. Only supported on web.
+  /// Client ID being used to connect to google sign-in. Only supported on Web
+  /// and iOS.
   final String? clientId;
 
+  /// Client ID of the backend server to which ID tokens will be sent. Only
+  /// supported on Android and iOS.
+  final String? serverClientId;
+
   final StreamController<GoogleSignInAccount?> _currentUserController =
       StreamController<GoogleSignInAccount?>.broadcast();
 
@@ -260,11 +266,12 @@ class GoogleSignIn {
   }
 
   Future<void> _ensureInitialized() {
-    return _initialization ??= GoogleSignInPlatform.instance.init(
+    return _initialization ??= GoogleSignInPlatform.instance.init2(
       signInOption: signInOption,
       scopes: scopes,
       hostedDomain: hostedDomain,
       clientId: clientId,
+      serverClientId: serverClientId,
     )..catchError((dynamic _) {
         // Invalidate initialization if it errors out.
         _initialization = null;

packages/google_sign_in/google_sign_in/pubspec.yaml

@@ -44,3 +44,14 @@ false_secrets:
   - /example/ios/RunnerTests/GoogleSignInTests.m
   - /example/lib/main.dart
   - /example/web/index.html
+
+# FOR TESTING ONLY. DO NOT MERGE.
+dependency_overrides:
+  google_sign_in_android:
+    path: ../../google_sign_in/google_sign_in_android
+  google_sign_in_ios:
+    path: ../../google_sign_in/google_sign_in_ios
+  google_sign_in_platform_interface:
+    path: ../../google_sign_in/google_sign_in_platform_interface
+  google_sign_in_web:
+    path: ../../google_sign_in/google_sign_in_web

packages/google_sign_in/google_sign_in/test/google_sign_in_test.dart

@@ -96,6 +96,27 @@ void main() {
             'scopes': <String>[],
             'hostedDomain': null,
             'clientId': fakeClientId,
+            'serverClientId': null,
+          }),
+          isMethodCall('signIn', arguments: null),
+        ],
+      );
+    });
+
+    test('signIn prioritize serverClientId parameter when available', () async {
+      const String fakeServerClientId = 'fakeServerClientId';
+      googleSignIn = GoogleSignIn(serverClientId: fakeServerClientId);
+      await googleSignIn.signIn();
+      expect(googleSignIn.currentUser, isNotNull);
+      expect(
+        log,
+        <Matcher>[
+          isMethodCall('init', arguments: <String, dynamic>{
+            'signInOption': 'SignInOption.standard',
+            'scopes': <String>[],
+            'hostedDomain': null,
+            'clientId': null,
+            'serverClientId': fakeServerClientId,
           }),
           isMethodCall('signIn', arguments: null),
         ],
@@ -431,5 +452,6 @@ Matcher _isSignInMethodCall({String signInOption = 'SignInOption.standard'}) {
     'scopes': <String>[],
     'hostedDomain': null,
     'clientId': null,
+    'serverClientId': null,
   });
 }

packages/google_sign_in/google_sign_in_android/CHANGELOG.md

@@ -1,3 +1,11 @@
+## Next
+
+* **BREAKING CHANGES**:
+  * Add `serverClientId` parameter to `IDelegate.init`.
+  * Make `clientId` unsupported and support `serverClientId` instead.
+    Historically `clientId` was interpreted as `serverClientId`, but only on Android. On
+    other platforms it was interpreted as the OAuth `clientId` of the app.
+
 ## 5.2.5
 
-* Splits from `video_player` as a federated implementation.
+* Splits from `google_sign_in` as a federated implementation.

packages/google_sign_in/google_sign_in_android/android/src/main/java/io/flutter/plugins/googlesignin/GoogleSignInPlugin.java

@@ -137,7 +137,9 @@ public void onMethodCall(MethodCall call, Result result) {
         List<String> requestedScopes = call.argument("scopes");
         String hostedDomain = call.argument("hostedDomain");
         String clientId = call.argument("clientId");
-        delegate.init(result, signInOption, requestedScopes, hostedDomain, clientId);
+        String serverClientId = call.argument("serverClientId");
+        delegate.init(
+            result, signInOption, requestedScopes, hostedDomain, clientId, serverClientId);
         break;
 
       case METHOD_SIGN_IN_SILENTLY:
@@ -193,7 +195,8 @@ public void init(
         String signInOption,
         List<String> requestedScopes,
         String hostedDomain,
-        String clientId);
+        String clientId,
+        String serverClientId);
 
     /**
      * Returns the account information for the user who is signed in to this app. If no user is
@@ -318,7 +321,8 @@ public void init(
         String signInOption,
         List<String> requestedScopes,
         String hostedDomain,
-        String clientId) {
+        String clientId,
+        String serverClientId) {
       try {
         GoogleSignInOptions.Builder optionsBuilder;
 
@@ -335,20 +339,28 @@ public void init(
             throw new IllegalStateException("Unknown signInOption");
         }
 
-        // Only requests a clientId if google-services.json was present and parsed
-        // by the google-services Gradle script.
-        // TODO(jackson): Perhaps we should provide a mechanism to override this
-        // behavior.
-        int clientIdIdentifier =
-            context
-                .getResources()
-                .getIdentifier("default_web_client_id", "string", context.getPackageName());
         if (!Strings.isNullOrEmpty(clientId)) {
-          optionsBuilder.requestIdToken(clientId);
-          optionsBuilder.requestServerAuthCode(clientId);
-        } else if (clientIdIdentifier != 0) {
-          optionsBuilder.requestIdToken(context.getString(clientIdIdentifier));
-          optionsBuilder.requestServerAuthCode(context.getString(clientIdIdentifier));
+          throw new IllegalArgumentException(
+              "clientId is not supported on Android. "
+                  + "To set a server client ID use serverClientId instead.");
+        }
+
+        if (Strings.isNullOrEmpty(serverClientId)) {
+          // Only requests a clientId if google-services.json was present and parsed
+          // by the google-services Gradle script.
+          // TODO(jackson): Perhaps we should provide a mechanism to override this
+          // behavior.
+          int webClientIdIdentifier =
+              context
+                  .getResources()
+                  .getIdentifier("default_web_client_id", "string", context.getPackageName());
+          if (webClientIdIdentifier != 0) {
+            serverClientId = context.getString(webClientIdIdentifier);
+          }
+        }
+        if (!Strings.isNullOrEmpty(serverClientId)) {
+          optionsBuilder.requestIdToken(serverClientId);
+          optionsBuilder.requestServerAuthCode(serverClientId);
         }
         for (String scope : requestedScopes) {
           optionsBuilder.requestScopes(new Scope(scope));

packages/google_sign_in/google_sign_in_android/example/pubspec.yaml

@@ -28,3 +28,10 @@ dev_dependencies:
 
 flutter:
   uses-material-design: true
+
+# FOR TESTING ONLY. DO NOT MERGE.
+dependency_overrides:
+  google_sign_in_android:
+    path: ../../../google_sign_in/google_sign_in_android
+  google_sign_in_platform_interface:
+    path: ../../../google_sign_in/google_sign_in_platform_interface

packages/google_sign_in/google_sign_in_android/pubspec.yaml

@@ -33,3 +33,8 @@ dev_dependencies:
 false_secrets:
   - /example/android/app/google-services.json
   - /example/lib/main.dart
+
+# FOR TESTING ONLY. DO NOT MERGE.
+dependency_overrides:
+  google_sign_in_platform_interface:
+    path: ../../google_sign_in/google_sign_in_platform_interface

packages/google_sign_in/google_sign_in_ios/CHANGELOG.md

@@ -1,3 +1,8 @@
+## Next
+
+* Remove the requirement for a `GoogleService-Info` file.
+* Add support for `serverClientId` configuration option.
+
 ## 5.2.5
 
-* Splits from `video_player` as a federated implementation.
+* Splits from `google_sign_in` as a federated implementation.

packages/google_sign_in/google_sign_in_ios/example/ios/RunnerTests/GoogleSignInTests.m

@@ -153,6 +153,20 @@ - (void)testInitDynamicClientId {
   OCMVerify([self.mockSignIn setClientID:@"mockClientId"]);
 }
 
+- (void)testInitDynamicServerClientId {
+  FlutterMethodCall *methodCall =
+      [FlutterMethodCall methodCallWithMethodName:@"init"
+                                        arguments:@{@"serverClientId" : @"mockServerClientId"}];
+
+  XCTestExpectation *expectation = [self expectationWithDescription:@"expect result returns true"];
+  [self.plugin handleMethodCall:methodCall
+                         result:^(id r) {
+                           [expectation fulfill];
+                         }];
+  [self waitForExpectationsWithTimeout:5.0 handler:nil];
+  OCMVerify([self.mockSignIn setServerClientID:@"mockServerClientId"]);
+}
+
 #pragma mark - Is signed in
 
 - (void)testIsNotSignedIn {

packages/google_sign_in/google_sign_in_ios/example/pubspec.yaml

@@ -27,3 +27,10 @@ dev_dependencies:
 
 flutter:
   uses-material-design: true
+
+# FOR TESTING ONLY. DO NOT MERGE.
+dependency_overrides:
+  google_sign_in_ios:
+    path: ../../../google_sign_in/google_sign_in_ios
+  google_sign_in_platform_interface:
+    path: ../../../google_sign_in/google_sign_in_platform_interface

packages/google_sign_in/google_sign_in_ios/ios/Classes/FLTGoogleSignInPlugin.m

@@ -84,32 +84,45 @@ - (void)handleMethodCall:(FlutterMethodCall *)call result:(FlutterResult)result
                                  message:@"Games sign in is not supported on iOS"
                                  details:nil]);
     } else {
+      NSMutableDictionary<NSString *, NSString *> *plist = nil;
       NSString *path = [[NSBundle mainBundle] pathForResource:@"GoogleService-Info"
                                                        ofType:@"plist"];
       if (path) {
-        NSMutableDictionary<NSString *, NSString *> *plist =
-            [[NSMutableDictionary alloc] initWithContentsOfFile:path];
-        BOOL hasDynamicClientId = [call.arguments[@"clientId"] isKindOfClass:[NSString class]];
-
-        if (hasDynamicClientId) {
-          self.signIn.clientID = call.arguments[@"clientId"];
-        } else {
-          self.signIn.clientID = plist[kClientIdKey];
+        plist = [[NSMutableDictionary alloc] initWithContentsOfFile:path];
+      }
+
+      BOOL hasDynamicClientId = [call.arguments[@"clientId"] isKindOfClass:[NSString class]];
+      if (hasDynamicClientId) {
+        self.signIn.clientID = call.arguments[@"clientId"];
+      } else {
+        if (!plist) {
+          result([FlutterError errorWithCode:@"missing-config"
+                                     message:@"GoogleService-Info.plist file not found"
+                                     details:nil]);
+          return;
         }
+        self.signIn.clientID = plist[kClientIdKey];
+      }
 
+      BOOL hasDynamicServerClientId =
+          [call.arguments[@"serverClientId"] isKindOfClass:[NSString class]];
+      if (hasDynamicServerClientId) {
+        self.signIn.serverClientID = call.arguments[@"serverClientId"];
+      } else if (plist) {
         self.signIn.serverClientID = plist[kServerClientIdKey];
-        self.signIn.scopes = call.arguments[@"scopes"];
-        if (call.arguments[@"hostedDomain"] == [NSNull null]) {
-          self.signIn.hostedDomain = nil;
-        } else {
-          self.signIn.hostedDomain = call.arguments[@"hostedDomain"];
-        }
-        result(nil);
       } else {
-        result([FlutterError errorWithCode:@"missing-config"
-                                   message:@"GoogleService-Info.plist file not found"
-                                   details:nil]);
+        self.signIn.serverClientID = nil;
       }
+
+      self.signIn.scopes = call.arguments[@"scopes"];
+
+      if (call.arguments[@"hostedDomain"] == [NSNull null]) {
+        self.signIn.hostedDomain = nil;
+      } else {
+        self.signIn.hostedDomain = call.arguments[@"hostedDomain"];
+      }
+
+      result(nil);
     }
   } else if ([call.method isEqualToString:@"signInSilently"]) {
     if ([self setAccountRequest:result]) {

packages/google_sign_in/google_sign_in_ios/pubspec.yaml

@@ -33,3 +33,8 @@ false_secrets:
   - /example/ios/Runner/GoogleService-Info.plist
   - /example/ios/RunnerTests/GoogleSignInTests.m
   - /example/lib/main.dart
+
+# FOR TESTING ONLY. DO NOT MERGE.
+dependency_overrides:
+  google_sign_in_platform_interface:
+    path: ../../google_sign_in/google_sign_in_platform_interface

packages/google_sign_in/google_sign_in_platform_interface/CHANGELOG.md

@@ -1,3 +1,8 @@
+## Next
+
+* Add `GoogleSignInPlatform.init2` and deprecate `GoogleSignInPlatform.init` to support the
+  `serverClientId` parameter.
+
 ## 2.1.2
 
 * Internal code cleanup for stricter analysis options.

packages/google_sign_in/google_sign_in_platform_interface/lib/google_sign_in_platform_interface.dart

@@ -66,6 +66,9 @@ abstract class GoogleSignInPlatform {
   /// Initializes the plugin. You must call this method before calling other
   /// methods.
   ///
+  /// This method is deprecated and will be removed in the future.
+  /// Use [init2] instead.
+  ///
   /// The [hostedDomain] argument specifies a hosted domain restriction. By
   /// setting this, sign in will be restricted to accounts of the user in the
   /// specified domain. By default, the list of accounts will not be restricted.
@@ -89,6 +92,38 @@ abstract class GoogleSignInPlatform {
     throw UnimplementedError('init() has not been implemented.');
   }
 
+  /// Initializes the plugin. You must call this method before calling other
+  /// methods.
+  ///
+  /// The [hostedDomain] argument specifies a hosted domain restriction. By
+  /// setting this, sign in will be restricted to accounts of the user in the
+  /// specified domain. By default, the list of accounts will not be restricted.
+  ///
+  /// The list of [scopes] are OAuth scope codes to request when signing in.
+  /// These scope codes will determine the level of data access that is granted
+  /// to your application by the user. The full list of available scopes can be
+  /// found here: <https://developers.google.com/identity/protocols/googlescopes>
+  ///
+  /// The [signInOption] determines the user experience. [SigninOption.games] is
+  /// only supported on Android.
+  ///
+  /// See:
+  /// https://developers.google.com/identity/sign-in/web/reference#gapiauth2initparams
+  Future<void> init2({
+    List<String> scopes = const <String>[],
+    SignInOption signInOption = SignInOption.standard,
+    String? hostedDomain,
+    String? clientId,
+    String? serverClientId,
+  }) async {
+    return init(
+      scopes: scopes,
+      signInOption: signInOption,
+      hostedDomain: hostedDomain,
+      clientId: clientId,
+    );
+  }
+
   /// Attempts to reuse pre-existing credentials to sign in again, without user interaction.
   Future<GoogleSignInUserData?> signInSilently() async {
     throw UnimplementedError('signInSilently() has not been implemented.');