// Author: fruit.com.cn

import 'dart:async';

import 'package:flutter/material.dart';

import '../../core/data/models/drama.dart';
import '../../core/data/models/watch_progress.dart';
import '../../core/data/remote/api_exception.dart';
import '../../core/data/repositories/search_repository.dart';
import '../../core/data/repositories/watch_history_repository.dart';
import '../../l10n/app_localizations.dart';

enum DiscoverPageAction { home, my, watchlist, detail, resume }

class DiscoverLogic extends ChangeNotifier {
  DiscoverLogic({
    required this.history,
    required this.drama,
    this.searchRepository,
  }) {
    refreshPosition();
  }

  final WatchHistoryRepository history;
  final SearchRepository? searchRepository;
  Drama drama;
  late Future<Duration?> position;
  WatchProgress? resumeRecord;
  final TextEditingController search = TextEditingController();
  final FocusNode searchFocus = FocusNode();
  final ScrollController scroll = ScrollController();
  bool searchOpen = false;

  /// 搜索防抖与分页口径：与后端 `/app/search` 一致。
  Duration searchDebounce = const Duration(milliseconds: 350);
  static const int searchPageSize = 20;
  List<Drama> searchResults = const [];
  int searchTotal = 0;
  bool searchLoading = false;
  String? searchError;
  Timer? _searchTimer;
  String _lastRequestedQuery = '';
  int _searchRequest = 0;
  bool _disposed = false;

  void notify() {
    if (!_disposed) notifyListeners();
  }

  void refreshPosition() {
    // 续看位置来自服务端（每剧一条记录）；未登录或没有记录时给 null，UI 显示"从头看"
    position = history
        .resumePointFor(drama.id)
        .then((point) => point?.position)
        .catchError((Object _) => null);
    refreshResume();
  }

  Future<void> refreshResume() async {
    try {
      final recent = await history.recent(limit: 1);
      if (recent.isEmpty || recent.first.finished) {
        resumeRecord = null;
      } else {
        resumeRecord = recent.first;
      }
    } catch (_) {
      resumeRecord = null;
    }
    notify();
  }

  bool get hasSearchQuery => search.text.trim().isNotEmpty;

  /// 输入变化只触发后端查询；本地不再做标题/简介匹配。
  void onSearchChanged() {
    final query = search.text.trim();
    if (query.isEmpty) {
      _resetSearch();
      notify();
      return;
    }
    notify();
    _scheduleSearch(query);
  }

  /// 搜索态展示后端结果，非搜索态展示剧场自身的可见短剧。
  List<Drama> visibleDramas(List<Drama> fallback) {
    if (!hasSearchQuery) return fallback;
    return searchResults;
  }

  Future<void> retrySearch() async {
    final query = search.text.trim();
    if (query.isEmpty) return;
    await _runSearch(query);
  }

  void _resetSearch() {
    _searchTimer?.cancel();
    _searchRequest++;
    searchResults = const [];
    searchTotal = 0;
    searchLoading = false;
    searchError = null;
    _lastRequestedQuery = '';
  }

  void _scheduleSearch(String query) {
    final alreadyRequested = query == _lastRequestedQuery;
    if (alreadyRequested && (searchLoading || searchResults.isNotEmpty || searchError != null)) {
      return;
    }
    _lastRequestedQuery = query;
    _searchTimer?.cancel();
    if (searchDebounce == Duration.zero) {
      unawaited(_runSearch(query));
      return;
    }
    _searchTimer = Timer(searchDebounce, () => unawaited(_runSearch(query)));
  }

  Future<void> _runSearch(String query) async {
    final repository = searchRepository;
    if (repository == null) return;
    final request = ++_searchRequest;
    searchLoading = true;
    searchError = null;
    notify();
    try {
      final result = await repository.search(
        query,
        pageIndex: 1,
        pageSize: searchPageSize,
      );
      if (request != _searchRequest) return;
      searchResults = result.list;
      searchTotal = result.total;
    } on ApiException catch (exception) {
      _applySearchError(request, exception.message);
    } catch (_) {
      _applySearchError(request, 'searchFailed');
    } finally {
      if (request == _searchRequest) {
        searchLoading = false;
        notify();
      }
    }
  }

  void _applySearchError(int request, String message) {
    if (request != _searchRequest) return;
    searchError = message;
    searchResults = const [];
    searchTotal = 0;
  }

  Drama? resumeDrama(List<Drama> dramas) {
    final record = resumeRecord;
    if (record == null) return null;
    for (final drama in dramas) {
      if (drama.id == record.dramaId) return drama;
    }
    return null;
  }

  bool get showSearch => searchOpen || search.text.isNotEmpty;

  void openSearch() {
    searchOpen = true;
    notify();
    searchFocus.requestFocus();
  }

  void syncDrama({
    required bool active,
    required bool wasActive,
    required Drama nextDrama,
    required bool dramaChanged,
    required int searchRequest,
    required int previousSearchRequest,
    required bool Function() isActive,
  }) {
    if (active && (!wasActive || dramaChanged)) {
      drama = nextDrama;
      refreshPosition();
      notify();
    }
    if (active && searchRequest != previousSearchRequest) {
      searchOpen = true;
      notify();
      WidgetsBinding.instance.addPostFrameCallback((_) {
        if (isActive()) searchFocus.requestFocus();
      });
    }
  }

  void act(
    BuildContext context,
    DiscoverPageAction action, {
    required bool embedded,
    ValueChanged<DiscoverPageAction>? onAction,
  }) {
    if (embedded) {
      onAction?.call(action);
    } else {
      Navigator.pop(context, action);
    }
  }

  Drama? dramaFor(String? dramaId, List<Drama> dramas) {
    for (final item in dramas) {
      if (item.id == dramaId) return item;
    }
    return null;
  }

  void openCard(
    BuildContext context,
    Drama? selected, {
    required bool embedded,
    ValueChanged<Drama>? onDramaSelected,
    ValueChanged<DiscoverPageAction>? onAction,
  }) {
    if (selected == null) {
      unavailable(context);
    } else if (embedded && onDramaSelected != null) {
      onDramaSelected(selected);
    } else {
      act(
        context,
        DiscoverPageAction.detail,
        embedded: embedded,
        onAction: onAction,
      );
    }
  }

  void unavailable(BuildContext context) {
    final l10n = AppLocalizations.of(context)!;
    ScaffoldMessenger.of(
      context,
    ).showSnackBar(SnackBar(content: Text(l10n.artworkOnlyNotice)));
  }

  void catalogInfo(BuildContext context) {
    final l10n = AppLocalizations.of(context)!;
    ScaffoldMessenger.of(
      context,
    ).showSnackBar(SnackBar(content: Text(l10n.demoCatalogNotice)));
  }

  @override
  void dispose() {
    _disposed = true;
    _searchTimer?.cancel();
    search.dispose();
    searchFocus.dispose();
    scroll.dispose();
    super.dispose();
  }
}