bloc.dart

class AppInSessionState extends StatelessWidget {
  final Widget child;

  const AppInSessionState({Key key, this.child}) : super(key: key);
  @override
  Widget build(BuildContext context) {
    final sessionBloc = Provider.of<SessionBloc>(context);
    return BlocProvider<AuthorBloc>(
      builder: (_, bloc) => bloc ?? AuthorBloc(sessionBloc, AuthorApi()),
      onDispose: (_, bloc) => bloc.dispose(),
      child: BlocProvider<BottomBarBloc>(
        builder: (_, bloc) => bloc ?? BottomBarBloc(),
        onDispose: (_, bloc) => bloc.dispose(),
        child: BlocProvider<QuestBloc>(
          builder: (_, bloc) => bloc ?? QuestBloc(sessionBloc, QuestApi()),
          onDispose: (_, bloc) => bloc.dispose(),
          child: child,
        ),
      ),
    );
  }
}

class AppState extends StatelessWidget {
  final Widget child;

  const AppState({Key key, this.child}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return BlocProvider<SessionBloc>(
      builder: (_, sessionBloc) =>
          sessionBloc ??
          SessionBloc(
              authApi: AuthApi(), targetPlatform: Theme.of(context).platform),
      onDispose: (_, bloc) => bloc.dispose(),
      child: AppInSessionState(child: child),
    );
  }
  
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return AppState(
        child: MaterialApp(),
    )
}