mnemo_cards/lib/features/packs/pack_holder.dart

import 'dart:async';

import 'package:rxdart/rxdart.dart';

class PackHolder {
  final StreamController<PackState> _streamController =
      StreamController.broadcast();
  PackState _state;

  PackHolder() : _state = PackState.empty;

  void setPacksWithCards(
    Iterable<String> packs,
  ) {
    _state = PackState(packs.toSet());
    _streamController.add(_state);
  }

  void removePackWithCards(String id) =>
      setPacksWithCards(state.packsWithCards.toList()..remove(id));

  void clear() {
    _state = PackState.empty;
    _streamController.add(_state);
  }

  PackState get state => _state;

  Stream<PackState> get asStream => _streamController.stream.startWith(_state);
}

class PackState {
  final Set<String> packsWithCards;

  static const empty = PackState({});

  const PackState(
    this.packsWithCards,
  );
}