import 'dart:async';
import 'package:flutter_bloc/flutter_bloc.dart';
import 'package:finlytic_app/features/news/repositories/news_repository.dart';
import 'news_event.dart';
import 'news_state.dart';

class NewsBloc extends Bloc<NewsEvent, NewsState> {
  final NewsRepository repository;
  static const int pageSize = 20;
  StreamSubscription? _liveNewsSubscription;

  NewsBloc({required this.repository}) : super(NewsInitial()) {
    on<FetchNews>(_onFetchNews);
    on<LoadMoreNews>(_onLoadMoreNews);
    on<ReceiveLiveNews>(_onReceiveLiveNews);

    // Subscribe to live news pushed over the central SignalRService's
    // `/hubs/news` connection (authenticated, managed in main.dart).
    _liveNewsSubscription = repository.liveNewsStream.listen((article) {
      add(ReceiveLiveNews(article));
    });
  }

  Future<void> _onFetchNews(FetchNews event, Emitter<NewsState> emit) async {
    try {
      emit(NewsLoading());
      final articles = await repository.fetchNews(
        page: 1,
        pageSize: pageSize,
        symbol: event.symbol,
        isin: event.isin,
        date: event.date,
      );
      
      emit(NewsLoaded(
        articles: articles,
        hasReachedMax: articles.length < pageSize,
        currentPage: 1,
        symbol: event.symbol,
        isin: event.isin,
        date: event.date,
      ));
    } catch (e) {
      emit(NewsError("Failed to fetch news. Please try again."));
    }
  }

  Future<void> _onLoadMoreNews(LoadMoreNews event, Emitter<NewsState> emit) async {
    if (state is NewsLoaded) {
      final currentState = state as NewsLoaded;
      if (currentState.hasReachedMax) return;

      try {
        final nextPage = currentState.currentPage + 1;
        final articles = await repository.fetchNews(
          page: nextPage,
          pageSize: pageSize,
          symbol: currentState.symbol,
          isin: currentState.isin,
          date: currentState.date,
        );

        if (articles.isEmpty) {
          emit(currentState.copyWith(hasReachedMax: true));
        } else {
          emit(NewsLoaded(
            articles: currentState.articles + articles,
            hasReachedMax: articles.length < pageSize,
            currentPage: nextPage,
            symbol: currentState.symbol,
            isin: currentState.isin,
            date: currentState.date,
          ));
        }
      } catch (e) {
        emit(NewsError("Failed to load more news."));
      }
    }
  }

  void _onReceiveLiveNews(ReceiveLiveNews event, Emitter<NewsState> emit) {
    if (state is NewsLoaded) {
      final currentState = state as NewsLoaded;
      
      // Check if the article matches current filters before prepending
      bool matchesFilter = true;
      if (currentState.symbol != null || currentState.isin != null) {
        // Needs proper matching logic if needed, but for now we prepend if there's no filter or if it matches
        // Assuming we prepend it regardless for live feed, or we could filter based on MatchedAssets if added to model.
      }
      
      if (matchesFilter) {
        // Prepend new article to the top of the list!
        final updatedArticles = [event.article, ...currentState.articles];
        emit(currentState.copyWith(articles: updatedArticles));
      }
    }
  }

  @override
  Future<void> close() {
    _liveNewsSubscription?.cancel();
    repository.dispose();
    return super.close();
  }
}