feat(firebase_analytics): support getSessionId for android and apple platforms

packages/firebase_analytics/firebase_analytics/android/src/main/java/io/flutter/plugins/firebase/analytics/FlutterFirebaseAnalyticsPlugin.java

@@ -136,6 +136,9 @@ public void onMethodCall(@NonNull MethodCall call, @NonNull Result result) {
       case "Analytics#getAppInstanceId":
         methodCallTask = handleGetAppInstanceId();
         break;
+      case "Analytics#getSessionId":
+        methodCallTask = handleGetSessionId();
+        break;
       default:
         result.notImplemented();
         return;
@@ -154,6 +157,21 @@ public void onMethodCall(@NonNull MethodCall call, @NonNull Result result) {
         });
   }
 
+  private Task<Long> handleGetSessionId() {
+    TaskCompletionSource<Long> taskCompletionSource = new TaskCompletionSource<>();
+
+    cachedThreadPool.execute(
+        () -> {
+          try {
+            taskCompletionSource.setResult(Tasks.await(analytics.getSessionId()));
+          } catch (Exception e) {
+            taskCompletionSource.setException(e);
+          }
+        });
+
+    return taskCompletionSource.getTask();
+  }
+
   private Task<Void> handleLogEvent(final Map<String, Object> arguments) {
     TaskCompletionSource<Void> taskCompletionSource = new TaskCompletionSource<>();
 

packages/firebase_analytics/firebase_analytics/ios/Classes/FLTFirebaseAnalyticsPlugin.m

@@ -72,13 +72,25 @@ - (void)handleMethodCall:(FlutterMethodCall *)call result:(FlutterResult)result
     [self setDefaultEventParameters:call.arguments withMethodCallResult:methodCallResult];
   } else if ([@"Analytics#getAppInstanceId" isEqualToString:call.method]) {
     [self getAppInstanceIdWithMethodCallResult:methodCallResult];
+  } else if ([@"Analytics#getSessionId" isEqualToString:call.method]) {
+    [self getSessionIdWithMethodCallResult:methodCallResult];
   } else {
     result(FlutterMethodNotImplemented);
   }
 }
 
 #pragma mark - Firebase Analytics API
 
+- (void)getSessionIdWithMethodCallResult:(FLTFirebaseMethodCallResult *)result {
+  [FIRAnalytics sessionIDWithCompletion:^(int64_t sessionID, NSError *_Nullable error) {
+    if (error != nil) {
+      result.error(nil, nil, nil, error);
+    } else {
+      result.success([NSNumber numberWithLongLong:sessionID]);
+    }
+  }];
+}
+
 - (void)logEvent:(id)arguments withMethodCallResult:(FLTFirebaseMethodCallResult *)result {
   NSString *eventName = arguments[kFLTFirebaseAnalyticsEventName];
   id parameterMap = arguments[kFLTFirebaseAnalyticsParameters];

packages/firebase_analytics/firebase_analytics/lib/src/firebase_analytics.dart

@@ -75,6 +75,12 @@ class FirebaseAnalytics extends FirebasePluginPlatform {
     return _delegate.getAppInstanceId();
   }
 
+  /// Retrieves the session id from the client. Returns null if
+  /// analyticsStorageConsentGranted is false or session is expired.
+  Future<int?> getSessionId() {
+    return _delegate.getSessionId();
+  }
+
   /// Logs a custom Flutter Analytics event with the given [name] and event
   /// [parameters].
   ///

packages/firebase_analytics/firebase_analytics_platform_interface/lib/src/method_channel/method_channel_firebase_analytics.dart

@@ -44,6 +44,15 @@ class MethodChannelFirebaseAnalytics extends FirebaseAnalyticsPlatform {
     return Future.value(true);
   }
 
+  @override
+  Future<int?> getSessionId() {
+    try {
+      return channel.invokeMethod<int>('Analytics#getSessionId');
+    } catch (e, s) {
+      convertPlatformException(e, s);
+    }
+  }
+
   @override
   Future<void> logEvent({
     required String name,

packages/firebase_analytics/firebase_analytics_platform_interface/lib/src/platform_interface/platform_interface_firebase_analytics.dart

@@ -74,6 +74,10 @@ abstract class FirebaseAnalyticsPlatform extends PlatformInterface {
     throw UnimplementedError('getAppInstanceId() is not implemented');
   }
 
+  Future<int?> getSessionId() {
+    throw UnimplementedError('getSessionId() is not implemented');
+  }
+
   /// Logs a custom Flutter Analytics event with the given [name] and event
   /// [parameters].
   ///

packages/firebase_analytics/firebase_analytics_platform_interface/test/method_channel_tests/method_channel_firebase_analytics_test.dart

@@ -24,6 +24,8 @@ void main() {
         switch (call.method) {
           case 'Analytics#getAppInstanceId':
             return 'ABCD1234';
+          case 'Analytics#getSessionId':
+            return 0;
 
           default:
             return true;
@@ -133,6 +135,19 @@ void main() {
       );
     });
 
+    test('getSessionId', () async {
+      await analytics.getSessionId();
+      expect(
+        methodCallLogger,
+        <Matcher>[
+          isMethodCall(
+            'Analytics#getSessionId',
+            arguments: null,
+          ),
+        ],
+      );
+    });
+
     test('logEvent', () async {
       await analytics.logEvent(
         name: 'test-event',

packages/firebase_analytics/firebase_analytics_platform_interface/test/platform_interface_tests/platform_interface_analytics_test.dart

@@ -211,6 +211,19 @@ void main() {
         ),
       );
     });
+
+    test('throws if .getSessionId() not implemented', () async {
+      await expectLater(
+        () => firebaseAnalyticsPlatform.getSessionId(),
+        throwsA(
+          isA<UnimplementedError>().having(
+            (e) => e.message,
+            'message',
+            'getSessionId() is not implemented',
+          ),
+        ),
+      );
+    });
   });
 }
 

packages/firebase_analytics/firebase_analytics_web/lib/firebase_analytics_web.dart

@@ -43,6 +43,12 @@ class FirebaseAnalyticsWeb extends FirebaseAnalyticsPlatform {
     return analytics_interop.Analytics.isSupported();
   }
 
+  @override
+  Future<int?> getSessionId() {
+    // TODO: change UnimplementedError to UnsupportedError
+    throw UnimplementedError('getSessionId() is not supported on Web.');
+  }
+
   @override
   Future<void> logEvent({
     required String name,

tests/integration_test/firebase_analytics/firebase_analytics_e2e_test.dart

@@ -19,6 +19,29 @@ void main() {
       );
     });
 
+    // getSessionId has to be first, else Android returns null
+    test(
+      'getSessionId',
+      () async {
+        if (kIsWeb) {
+          await expectLater(
+            FirebaseAnalytics.instance.getSessionId(),
+            throwsA(isA<UnimplementedError>()),
+          );
+        } else {
+          await expectLater(
+            FirebaseAnalytics.instance.setConsent(
+              analyticsStorageConsentGranted: true,
+            ),
+            completes,
+          );
+
+          final result = await FirebaseAnalytics.instance.getSessionId();
+          expect(result, isA<int>());
+        }
+      },
+    );
+
     test('isSupported', () async {
       final result = await FirebaseAnalytics.instance.isSupported();
       expect(result, isA<bool>());