TF-1821 Add Task and WorkerQueue object

(cherry picked from commit 42a90ce7c6bf773416db9a215e0a4c8b348c85ff)

lib/features/offline_mode/worker/hive_task.dart

@@ -0,0 +1,44 @@
+import 'dart:async';
+
+import 'package:equatable/equatable.dart';
+import 'package:tmail_ui_user/features/offline_mode/worker/hive_task_state.dart';
+
+class HiveTask<A> with EquatableMixin {
+  final String? id;
+  final A? action;
+  final Future<bool> Function()? conditionInvoked;
+  final Future Function() runnable;
+
+  HiveTask({
+    required this.runnable,
+    this.id,
+    this.action,
+    this.conditionInvoked,
+  });
+
+  Future execute() async {
+    final resultCompleter = Completer();
+
+    try {
+      if (conditionInvoked != null) {
+        final invoked = await conditionInvoked!.call();
+        if (invoked) {
+          final result = await runnable.call();
+          resultCompleter.complete(TaskSuccess(result: result));
+        } else {
+          resultCompleter.completeError(TaskFailure());
+        }
+      } else {
+        final result = await runnable.call();
+        resultCompleter.complete(TaskSuccess(result: result));
+      }
+    } catch (e) {
+      resultCompleter.completeError(TaskFailure(exception: e));
+    }
+
+    return resultCompleter.future;
+  }
+
+  @override
+  List<Object?> get props => [runnable, id, action, conditionInvoked];
+}

lib/features/offline_mode/worker/hive_task_state.dart

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+
+
+import 'package:core/presentation/state/failure.dart';
+import 'package:core/presentation/state/success.dart';
+
+class TaskSuccess extends Success {
+  final dynamic result;
+
+  TaskSuccess({this.result});
+
+  @override
+  List<Object?> get props => [result];
+}
+
+class TaskFailure extends Failure {
+  final dynamic exception;
+
+  TaskFailure({this.exception});
+
+  @override
+  List<Object?> get props => [exception];
+}

lib/features/offline_mode/worker/hive_worker_queue.dart

@@ -0,0 +1,65 @@
+
+import 'dart:async';
+import 'dart:collection';
+
+import 'package:core/utils/app_logger.dart';
+import 'package:tmail_ui_user/features/offline_mode/worker/hive_task.dart';
+
+abstract class WorkerQueue<A> {
+
+  final Queue<HiveTask<A>> queue = Queue<HiveTask<A>>();
+  Completer? completer;
+
+  String get workerName;
+
+  Future addTask(HiveTask<A> task) {
+    queue.add(task);
+    log('WorkerQueue<$workerName>::addTask(): QUEUE_LENGTH: ${queue.length}');
+    return _processTask();
+  }
+
+  Future _processTask() async {
+    if (completer != null) {
+      return completer!.future;
+    }
+    completer = Completer();
+    if (queue.isNotEmpty) {
+      final firstTask = queue.removeFirst();
+      log('WorkerQueue<$workerName>::_processTask(): ${firstTask.id}');
+      firstTask.execute()
+        .then(_handleTaskExecuteCompleted)
+        .catchError(_handleTaskExecuteError);
+    } else {
+      completer?.complete();
+    }
+    return completer!.future;
+  }
+
+  void _handleTaskExecuteCompleted(dynamic value) {
+    log('WorkerQueue<$workerName>::_handleTaskExecuteCompleted(): $value');
+    completer?.complete();
+    _releaseCompleter();
+    if (queue.isNotEmpty) {
+      _processTask();
+    }
+  }
+
+  void _handleTaskExecuteError(error) {
+    log('WorkerQueue<$workerName>::_handleTaskExecuteError(): $error');
+    completer?.complete();
+    _releaseCompleter();
+    if (queue.isNotEmpty) {
+      _processTask();
+    }
+  }
+
+  void _releaseCompleter() {
+    completer = null;
+  }
+
+  Future release() async {
+    log('WorkerQueue<$workerName>::release():');
+    queue.clear();
+    _releaseCompleter();
+  }
+}