import 'dart:async';

import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:worldhopper/database/database.dart';
import 'package:worldhopper/models/downloaded_chapter.dart';
import 'package:worldhopper/models/downloaded_series.dart';
import 'package:worldhopper/models/entry.dart';
import 'package:worldhopper/models/feed.dart';
import 'package:worldhopper/models/server.dart';
import 'package:worldhopper/providers/feed_provider.dart';
import 'package:worldhopper/repositories/downloaded_chapters_repository.dart';
import 'package:worldhopper/repositories/downloaded_series_repository.dart';
import 'package:worldhopper/repositories/server_repository.dart';
import 'package:worldhopper/services/download_storage_service.dart';
import 'package:worldhopper/services/series_download_service.dart';

// --- Repository providers ---

final downloadedSeriesRepositoryProvider =
    Provider<DownloadedSeriesRepository>((ref) {
  return DownloadedSeriesRepository(DatabaseHelper.instance);
});

final downloadedChaptersRepositoryProvider =
    Provider<DownloadedChaptersRepository>((ref) {
  return DownloadedChaptersRepository(DatabaseHelper.instance);
});

// --- Service providers ---

final downloadStorageServiceProvider = Provider<DownloadStorageService>((ref) {
  return DownloadStorageService();
});

final seriesDownloadServiceProvider = Provider<SeriesDownloadService>((ref) {
  final seriesRepo = ref.watch(downloadedSeriesRepositoryProvider);
  final chaptersRepo = ref.watch(downloadedChaptersRepositoryProvider);
  final opdsRepo = ref.watch(feedRepositoryProvider);
  final service = SeriesDownloadService(
    seriesRepo: seriesRepo,
    chaptersRepo: chaptersRepo,
    opdsRepo: opdsRepo,
  );
  ref.onDispose(() => service.dispose());
  return service;
});

// --- Polling provider ---

/// Whether download polling is active (enables auto-refresh of download lists)
final downloadPollingActiveProvider = StateProvider<bool>((ref) => false);

/// Check if there are any active downloads in the DB
final hasActiveDownloadsProvider = FutureProvider<bool>((ref) async {
  final repository = ref.watch(downloadedSeriesRepositoryProvider);
  final series = await repository.getByStatus(DownloadStatus.downloading);
  return series.isNotEmpty;
});

/// Server lookup by ID (needed for retry operations)
final serverByIdProvider = FutureProvider.family<Server?, String>(
  (ref, serverId) async {
    final repo = ServerRepository();
    return await repo.getServer(serverId);
  },
);

// --- Data providers ---

/// All downloaded series for the library section
final downloadedSeriesListProvider =
    FutureProvider<List<DownloadedSeries>>((ref) async {
  final repository = ref.watch(downloadedSeriesRepositoryProvider);
  final isPolling = ref.watch(downloadPollingActiveProvider);

  if (isPolling) {
    Timer? timer;
    timer = Timer.periodic(const Duration(seconds: 2), (_) {
      ref.invalidateSelf();
    });
    ref.onDispose(() => timer?.cancel());
  }

  return await repository.getAll();
});

/// Chapters for a specific downloaded series
final downloadedChaptersProvider =
    FutureProvider.family<List<DownloadedChapter>, String>(
  (ref, seriesId) async {
    final repository = ref.watch(downloadedChaptersRepositoryProvider);
    final isPolling = ref.watch(downloadPollingActiveProvider);

    if (isPolling) {
      Timer? timer;
      timer = Timer.periodic(const Duration(seconds: 2), (_) {
        ref.invalidateSelf();
      });
      ref.onDispose(() => timer?.cancel());
    }

    return await repository.getChaptersForSeries(seriesId);
  },
);

/// Check if a series feed URL is downloaded (for badges on browse screen)
final seriesDownloadStatusProvider =
    FutureProvider.family<DownloadedSeries?, SeriesDownloadKey>(
  (ref, key) async {
    final repository = ref.watch(downloadedSeriesRepositoryProvider);
    return await repository.getByFeedUrl(key.serverId, key.feedUrl);
  },
);

/// Check if a specific chapter is downloaded (for badges)
final chapterDownloadStatusProvider =
    FutureProvider.family<DownloadedChapter?, ChapterDownloadKey>(
  (ref, key) async {
    final repository = ref.watch(downloadedChaptersRepositoryProvider);
    return await repository.getByEntryId(key.serverId, key.entryId);
  },
);

/// Find the next downloaded chapter after the current one in the same series
final nextDownloadedChapterProvider =
    FutureProvider.family<DownloadedChapter?, ChapterDownloadKey>(
  (ref, key) async {
    final repository = ref.watch(downloadedChaptersRepositoryProvider);
    final current = await repository.getByEntryId(key.serverId, key.entryId);
    if (current == null) return null;

    final chapters = await repository.getChaptersForSeries(current.seriesId);
    final currentIndex = chapters.indexWhere((c) => c.id == current.id);
    if (currentIndex < 0 || currentIndex >= chapters.length - 1) return null;

    final next = chapters[currentIndex + 1];
    return next.isComplete ? next : null;
  },
);

/// Stream of active download progress
final activeDownloadProgressProvider = StreamProvider<DownloadProgress>((ref) {
  final service = ref.watch(seriesDownloadServiceProvider);
  return service.progressStream;
});

// --- Notifier ---

/// Notifier for triggering download/cancel/delete actions
class DownloadNotifier extends StateNotifier<AsyncValue<void>> {
  final SeriesDownloadService _downloadService;
  final Ref _ref;

  DownloadNotifier(this._downloadService, this._ref)
      : super(const AsyncValue.data(null));

  /// Start downloading an entire series
  Future<void> startSeriesDownload({
    required Server server,
    required String feedUrl,
    required String feedTitle,
    required Feed initialFeed,
    String? coverUrl,
    String? thumbnailUrl,
  }) async {
    state = const AsyncValue.loading();
    _ref.read(downloadPollingActiveProvider.notifier).state = true;
    try {
      state = await AsyncValue.guard(() async {
        await _downloadService.startSeriesDownload(
          server: server,
          feedUrl: feedUrl,
          feedTitle: feedTitle,
          initialFeed: initialFeed,
          coverUrl: coverUrl,
          thumbnailUrl: thumbnailUrl,
        );
        _invalidateProviders();
      });
    } finally {
      _ref.read(downloadPollingActiveProvider.notifier).state = false;
    }
  }

  /// Download a single chapter
  Future<void> downloadChapter({
    required Server server,
    required Entry entry,
    required String seriesId,
    required String feedUrl,
    required String feedTitle,
  }) async {
    state = const AsyncValue.loading();
    state = await AsyncValue.guard(() async {
      await _downloadService.downloadSingleChapter(
        server: server,
        entry: entry,
        seriesId: seriesId,
        feedUrl: feedUrl,
        feedTitle: feedTitle,
      );
      _invalidateProviders();
    });
  }

  /// Cancel an active download
  void cancelDownload(String id) {
    _downloadService.cancelDownload(id);
    _invalidateProviders();
  }

  /// Delete a downloaded series
  Future<void> deleteSeries(String seriesId) async {
    state = const AsyncValue.loading();
    state = await AsyncValue.guard(() async {
      await _downloadService.deleteSeries(seriesId);
      _invalidateProviders();
    });
  }

  /// Delete a single downloaded chapter
  Future<void> deleteChapter(DownloadedChapter chapter) async {
    state = const AsyncValue.loading();
    state = await AsyncValue.guard(() async {
      await _downloadService.deleteChapter(chapter);
      _invalidateProviders();
    });
  }

  /// Retry a single failed chapter
  Future<void> retryChapter({
    required Server server,
    required DownloadedChapter chapter,
  }) async {
    _ref.read(downloadPollingActiveProvider.notifier).state = true;
    try {
      state = await AsyncValue.guard(() async {
        await _downloadService.retryChapter(server: server, chapter: chapter);
        _invalidateProviders();
      });
    } finally {
      _ref.read(downloadPollingActiveProvider.notifier).state = false;
    }
  }

  /// Retry all failed chapters in a series
  Future<void> retryFailedChapters({
    required Server server,
    required String seriesId,
  }) async {
    _ref.read(downloadPollingActiveProvider.notifier).state = true;
    try {
      state = await AsyncValue.guard(() async {
        await _downloadService.retryFailedChapters(
          server: server,
          seriesId: seriesId,
        );
        _invalidateProviders();
      });
    } finally {
      _ref.read(downloadPollingActiveProvider.notifier).state = false;
    }
  }

  void _invalidateProviders() {
    _ref.invalidate(downloadedSeriesListProvider);
    _ref.invalidate(seriesDownloadStatusProvider);
    _ref.invalidate(chapterDownloadStatusProvider);
  }
}

final downloadNotifierProvider =
    StateNotifierProvider<DownloadNotifier, AsyncValue<void>>((ref) {
  final downloadService = ref.watch(seriesDownloadServiceProvider);
  return DownloadNotifier(downloadService, ref);
});

// --- Key classes ---

class SeriesDownloadKey {
  final String serverId;
  final String feedUrl;

  const SeriesDownloadKey({
    required this.serverId,
    required this.feedUrl,
  });

  @override
  bool operator ==(Object other) =>
      identical(this, other) ||
      other is SeriesDownloadKey &&
          runtimeType == other.runtimeType &&
          serverId == other.serverId &&
          feedUrl == other.feedUrl;

  @override
  int get hashCode => Object.hash(serverId, feedUrl);
}

class ChapterDownloadKey {
  final String serverId;
  final String entryId;

  const ChapterDownloadKey({
    required this.serverId,
    required this.entryId,
  });

  @override
  bool operator ==(Object other) =>
      identical(this, other) ||
      other is ChapterDownloadKey &&
          runtimeType == other.runtimeType &&
          serverId == other.serverId &&
          entryId == other.entryId;

  @override
  int get hashCode => Object.hash(serverId, entryId);
}