WMSDK-595: Add queue for getDeviceUUID callbacks

mindbox_android/android/src/main/kotlin/cloud/mindbox/mindbox_android/MindboxAndroidPlugin.kt

@@ -18,13 +18,15 @@ import io.flutter.plugin.common.MethodChannel
 import io.flutter.plugin.common.MethodChannel.MethodCallHandler
 import io.flutter.plugin.common.MethodChannel.Result
 import io.flutter.plugin.common.PluginRegistry.NewIntentListener
+import java.util.concurrent.atomic.AtomicBoolean
+import java.util.concurrent.atomic.AtomicReference
 
 /** MindboxAndroidPlugin */
 class MindboxAndroidPlugin : FlutterPlugin, MethodCallHandler, ActivityAware, NewIntentListener {
     private lateinit var context: Activity
     private var binding: ActivityPluginBinding? = null
-    private var deviceUuidSubscription: String? = null
-    private var tokenSubscription: String? = null
+    private val deviceUuidSubscriptions = mutableListOf<String>()
+    private val tokenSubscriptions = mutableListOf<String>()
     private lateinit var channel: MethodChannel
 
     inner class InAppCallbackImpl : InAppCallback {
@@ -83,27 +85,76 @@ class MindboxAndroidPlugin : FlutterPlugin, MethodCallHandler, ActivityAware, Ne
                 }
             }
             "getDeviceUUID" -> {
-                if (deviceUuidSubscription != null) {
-                    Mindbox.disposeDeviceUuidSubscription(deviceUuidSubscription!!)
+                val subscriptionRef = AtomicReference<String?>(null)
+                val isResultSent = AtomicBoolean(false)
+
+                val subscriptionId = Mindbox.subscribeDeviceUuid { uuid ->
+                    if (isResultSent.compareAndSet(false, true)) {
+                        result.success(uuid)
+
+                        val id = subscriptionRef.get()
+                        if (id != null) {
+                            Mindbox.disposeDeviceUuidSubscription(id)
+                            deviceUuidSubscriptions.remove(id)
+                        }
+                    }
                 }
-                deviceUuidSubscription = Mindbox.subscribeDeviceUuid { uuid ->
-                    result.success(uuid)
+
+                subscriptionRef.set(subscriptionId)
+                deviceUuidSubscriptions.add(subscriptionId)
+
+                // If callback was synchronous, unsubscribe immediately
+                if (isResultSent.get()) {
+                    Mindbox.disposeDeviceUuidSubscription(subscriptionId)
+                    deviceUuidSubscriptions.remove(subscriptionId)
                 }
             }
             "getToken" -> {
-                if (tokenSubscription != null) {
-                    Mindbox.disposePushTokenSubscription(tokenSubscription!!)
+                val subscriptionRef = AtomicReference<String?>(null)
+                val isResultSent = AtomicBoolean(false)
+
+                val subscriptionId = Mindbox.subscribePushToken { token ->
+                    if (isResultSent.compareAndSet(false, true)) {
+                        result.success(token)
+
+                        val id = subscriptionRef.get()
+                        if (id != null) {
+                            Mindbox.disposePushTokenSubscription(id)
+                            tokenSubscriptions.remove(id)
+                        }
+                    }
                 }
-                tokenSubscription = Mindbox.subscribePushToken { token ->
-                    result.success(token)
+
+                subscriptionRef.set(subscriptionId)
+                tokenSubscriptions.add(subscriptionId)
+
+                if (isResultSent.get()) {
+                    Mindbox.disposePushTokenSubscription(subscriptionId)
+                    tokenSubscriptions.remove(subscriptionId)
                 }
             }
             "getTokens" -> {
-                if (tokenSubscription != null) {
-                    Mindbox.disposePushTokenSubscription(tokenSubscription!!)
+                val subscriptionRef = AtomicReference<String?>(null)
+                val isResultSent = AtomicBoolean(false)
+
+                val subscriptionId = Mindbox.subscribePushTokens { token ->
+                    if (isResultSent.compareAndSet(false, true)) {
+                        result.success(token)
+
+                        val id = subscriptionRef.get()
+                        if (id != null) {
+                            Mindbox.disposePushTokenSubscription(id)
+                            tokenSubscriptions.remove(id)
+                        }
+                    }
                 }
-                tokenSubscription = Mindbox.subscribePushTokens { token ->
-                    result.success(token)
+
+                subscriptionRef.set(subscriptionId)
+                tokenSubscriptions.add(subscriptionId)
+
+                if (isResultSent.get()) {
+                    Mindbox.disposePushTokenSubscription(subscriptionId)
+                    tokenSubscriptions.remove(subscriptionId)
                 }
             }
             "executeAsyncOperation" -> {

mindbox_platform_interface/lib/src/types/mindbox_method_handler.dart

@@ -84,8 +84,13 @@ class MindboxMethodHandler {
       final pendingCallbackMethodsCopy =
       List<_PendingCallbackMethod>.from(_pendingCallbackMethods);
       for (final callbackMethod in pendingCallbackMethodsCopy) {
-        callbackMethod.callback(
-            await channel.invokeMethod(callbackMethod.methodName) ?? 'null');
+        channel
+            .invokeMethod(callbackMethod.methodName)
+            .then((result) {
+          callbackMethod.callback(result ?? 'null');
+        }).catchError((e) {
+          _logError('Error processing pending method ${callbackMethod.methodName}: $e');
+        });
       }
       final pendingOperationsCopy =
       List<_PendingOperations>.from(_pendingOperations);
@@ -99,6 +104,8 @@ class MindboxMethodHandler {
           if (operation.errorCallback != null) {
             final mindboxError = _convertPlatformExceptionToMindboxError(e);
             operation.errorCallback!(mindboxError);
+          } else {
+            _logError('Error processing pending operation ${operation.methodName}: $e');
           }
         });
       }

mindbox_platform_interface/test/src/types/mindbox_method_handler_test.dart

@@ -1,5 +1,6 @@
 import 'dart:async';
 
+import 'package:flutter/services.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:mindbox_platform_interface/mindbox_platform_interface.dart';
 
@@ -405,6 +406,72 @@ void main() {
       expect(() => completer.future, throwsA(isA<MindboxInternalError>()));
     },
   );
+
+  test(
+    'Verify that init completes even if pending getDeviceUUID hangs, allowing retries',
+    () async {
+      int getDeviceUUIDCallCount = 0;
+
+      // Mock handler that hangs on first getDeviceUUID
+      Future slowMockMethodCallHandler(MethodCall methodCall) async {
+        switch (methodCall.method) {
+          case 'init':
+            return Future.value(true);
+          case 'getDeviceUUID':
+            getDeviceUUIDCallCount++;
+            if (getDeviceUUIDCallCount == 1) {
+              // First call hangs (pending one)
+              return Completer<String>().future;
+            } else {
+              // Subsequent calls succeed
+              return Future.value('retry-uuid');
+            }
+          case 'writeNativeLog':
+            return Future.value(null);
+          default:
+            return 'dummy-response';
+        }
+      }
+
+      TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger
+          .setMockMethodCallHandler(channel, slowMockMethodCallHandler);
+
+      // 1. Call getDeviceUUID before init. It goes to pending.
+      bool callback1Called = false;
+      handler.getDeviceUUID(callback: (uuid) {
+        callback1Called = true;
+      });
+
+      // 2. Call init.
+      final validConfig = Configuration(
+        domain: 'domain',
+        endpointIos: 'endpointIos',
+        endpointAndroid: 'endpointAndroid',
+        subscribeCustomerIfCreated: true,
+      );
+
+      // This should now complete even though the first getDeviceUUID is hanging
+      // Adding timeout to fail faster if regression occurs (hangs indefinitely)
+      await handler
+          .init(configuration: validConfig)
+          .timeout(const Duration(seconds: 5));
+
+      expect(getDeviceUUIDCallCount, equals(1),
+          reason: 'First call should have been triggered');
+      expect(callback1Called, isFalse,
+          reason: 'First callback is still hanging');
+
+      // 3. Call getDeviceUUID again (retry).
+      // This should succeed because init is complete.
+      final completer = Completer<String>();
+      handler.getDeviceUUID(callback: (uuid) => completer.complete(uuid));
+
+      final result = await completer.future.timeout(const Duration(seconds: 1));
+
+      expect(result, equals('retry-uuid'));
+      expect(getDeviceUUIDCallCount, equals(2));
+    },
+  );
 }
 
 class StubMindboxMethodHandler {