hamed/refactor_server_time_cubit (#221)

- refactor server time cubit

Author: hamed-rezaee

lib/state/server_time/server_time_bloc.dart

@@ -0,0 +1,57 @@
+import 'dart:async';
+
+import 'package:flutter_bloc/flutter_bloc.dart';
+
+import 'package:flutter_deriv_api/api/response/time_response_result.dart';
+import 'package:flutter_deriv_api/helpers/helpers.dart';
+import 'package:flutter_deriv_api/state/connection/connection_cubit.dart';
+
+part 'server_time_state.dart';
+
+/// A cubit to fetch and sync machine time with server time.
+class ServerTimeCubit extends Cubit<ServerTimeState> {
+  /// Initializes [ServerTimeCubit].
+  ServerTimeCubit(ConnectionCubit connectionCubit)
+      : super(InitialServerTime()) {
+    _connectionSubscription =
+        connectionCubit.stream.listen(_connectionListener);
+  }
+
+  late final StreamSubscription<ConnectionState> _connectionSubscription;
+
+  final Duration _fetchServerTimeDuration = const Duration(seconds: 90);
+  final Duration _fetchServerTimeTimeoutDuration = const Duration(seconds: 5);
+
+  Timer? _serverTimeInterval;
+
+  void _connectionListener(ConnectionState state) {
+    _fetchServerTime(state);
+
+    _serverTimeInterval = Timer.periodic(
+      _fetchServerTimeDuration,
+      (Timer timer) => _fetchServerTime(state),
+    );
+  }
+
+  Future<void> _fetchServerTime(ConnectionState state) async {
+    if (state is ConnectionConnectedState) {
+      try {
+        final TimeResponse serverTime = await TimeResponse.fetchTime()
+            .timeout(_fetchServerTimeTimeoutDuration);
+
+        emit(ServerTimeFetched(serverTime: serverTime.time));
+      } on Exception catch (e) {
+        emit(ServerTimeError('$e'));
+      }
+    } else {
+      _serverTimeInterval?.cancel();
+    }
+  }
+
+  @override
+  Future<void> close() async {
+    await _connectionSubscription.cancel();
+
+    return super.close();
+  }
+}

lib/state/server_time/server_time_cubit.dart

@@ -1,4 +1,4 @@
-part of 'server_time_bloc.dart';
+part of 'server_time_cubit.dart';
 
 /// Server time base states.
 abstract class ServerTimeState {
@@ -17,19 +17,13 @@ class InitialServerTime extends ServerTimeState {
   String toString() => 'ServerTimeState: InitialServerTime';
 }
 
-/// Shows that we are in the process of fetching server time.
-class FetchingServerTime extends ServerTimeState {
-  @override
-  String toString() => 'ServerTimeState: FetchingServerTime';
-}
-
 /// Server time fetched state.
 class ServerTimeFetched extends ServerTimeState {
   /// Initializes server time fetched state.
   ServerTimeFetched({this.serverTime, int? timeDifference})
       : super(
-          timeDifference =
-              getSecondsSinceEpochDateTime(serverTime)! - getCurrentLocalEpoch(),
+          timeDifference = getSecondsSinceEpochDateTime(serverTime)! -
+              getCurrentLocalEpoch(),
         );
 
   /// Fetched server time.