loading_status.dart

class LoadingStatus {
  BehaviorSubject<bool>? _loadingController;
  bool _isLoading = false;
  bool _streamedInitialEvent = false;

  set isLoading(bool isLoading) {
    _isLoading = isLoading;
    _publishLoadingState();
  }

  bool get isLoading => _isLoading;

  Stream<bool> listen() {
    _loadingController ??= BehaviorSubject(
        onListen: _publishInitialLoadingState,
        onCancel: () {
          _loadingController?.close();
          _loadingController = null;
          _streamedInitialEvent = false;
        });
    return _loadingController!.stream.distinct();
  }

  void _publishInitialLoadingState() {
    if (!_streamedInitialEvent) {
      _publishLoadingState();
      _streamedInitialEvent = true;
    }
  }

  void _publishLoadingState() {
    _loadingController?.sink.add(_isLoading);
  }
}