import 'dart:async';
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:firebase_core/firebase_core.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'social_feed_models.dart';
import 'social_feed_service.dart';

/// Provider for SocialFeedService singleton.
final socialFeedServiceProvider = Provider<SocialFeedService>((ref) {
  FirebaseFirestore? firestore;
  try {
    if (Firebase.apps.isNotEmpty) {
      firestore = FirebaseFirestore.instance;
    }
  } catch (_) {
    firestore = null;
  }
  final service = SocialFeedService(firestore: firestore);
  ref.onDispose(() {
    service.dispose();
  });
  return service;
});

/// State provider for the active feed filter tab.
final feedFilterStateProvider = StateProvider<FeedFilter>((ref) {
  return FeedFilter.allActivity;
});

/// StateNotifier providing instant synchronous initial feed items and reacting to changes.
class SocialFeedNotifier extends StateNotifier<List<SocialFeedItem>> {
  final SocialFeedService _service;
  final FeedFilter _filter;
  StreamSubscription<List<SocialFeedItem>>? _sub;

  SocialFeedNotifier(this._service, this._filter)
      : super(_service.getFilteredItems(filter: _filter)) {
    _sub = _service.getFeedStream(filter: _filter).listen((items) {
      state = items;
    });
  }

  @override
  void dispose() {
    _sub?.cancel();
    super.dispose();
  }
}

/// Primary feed provider with zero-latency synchronous initial data.
final socialFeedNotifierProvider =
    StateNotifierProvider.autoDispose<SocialFeedNotifier, List<SocialFeedItem>>(
        (ref) {
  final service = ref.watch(socialFeedServiceProvider);
  final filter = ref.watch(feedFilterStateProvider);
  return SocialFeedNotifier(service, filter);
});

/// Stream provider for the filtered community social feed (preserved for backwards compatibility).
final socialFeedStreamProvider =
    StreamProvider.autoDispose<List<SocialFeedItem>>((ref) {
  final service = ref.watch(socialFeedServiceProvider);
  final filter = ref.watch(feedFilterStateProvider);
  return service.getFeedStream(filter: filter);
});