import 'package:flutter/material.dart';
import 'package:provider/provider.dart';
import '../../models/data_models.dart';
import '../../providers/app_provider.dart';
import '../../utils/user_prefs.dart';
import '../../widgets/movie_status_bar.dart';
import '../../widgets/movie_list_item.dart';
import '../../widgets/animated_star_rating.dart';
import '../../widgets/shimmer_skeleton.dart';
import '../../widgets/fade_in_local_image.dart';

/// 观影标签页（分页 + 触底加载）
class MovieTabPage extends StatefulWidget {
  const MovieTabPage({super.key});

  @override
  State<MovieTabPage> createState() => _MovieTabPageState();
}

class _MovieTabPageState extends State<MovieTabPage> {
  int _layoutStyle = 0;
  final List<Movie> _items = [];
  bool _hasMore = true;
  bool _isLoading = false;
  int _offset = 0;
  int _lastStatusIndex = -1;
  bool _initialized = false;
  int _lastDataCount = -1;
  DateTime? _lastUpdatedAt;
  late ScrollController _scrollController;
  AppProvider? _provider;

  static const _statusMap = {0: 'watched', 1: 'watching', 2: 'want_to_watch'};

  @override
  void initState() {
    super.initState();
    _layoutStyle = UserPrefs().movieLayoutStyle;
    _scrollController = ScrollController()..addListener(_onScroll);
    WidgetsBinding.instance.addPostFrameCallback((_) {
      final provider = context.read<AppProvider>();
      _provider = provider;
      provider.addListener(_onDataChanged);
      _lastDataCount = provider.movies.length;
      if (provider.movies.isNotEmpty) _lastUpdatedAt = provider.movies.first.updatedAt;
      _loadFirst();
    });
  }

  @override
  void dispose() {
    _provider?.removeListener(_onDataChanged);
    _scrollController.dispose();
    super.dispose();
  }

  void _onDataChanged() {
    if (!_initialized || !mounted) return;
    final provider = context.read<AppProvider>();
    final count = provider.movies.length;
    final latest = provider.movies.isNotEmpty ? provider.movies.first.updatedAt : null;
    if (count != _lastDataCount || latest != _lastUpdatedAt) {
      _lastDataCount = count;
      _lastUpdatedAt = latest;
      WidgetsBinding.instance.addPostFrameCallback((_) {
        if (mounted) _loadFirst();
      });
    }
  }

  void _onScroll() {
    if (_scrollController.position.pixels >= _scrollController.position.maxScrollExtent - 200) {
      _loadMore();
    }
  }

  String get _currentStatus => _statusMap[context.read<AppProvider>().movieStatusIndex] ?? 'watched';

  Future<void> _loadFirst() async {
    final provider = context.read<AppProvider>();
    final statusIdx = provider.movieStatusIndex;
    _lastStatusIndex = statusIdx;
    _initialized = true;
    final status = _statusMap[statusIdx] ?? 'watched';
    setState(() { _isLoading = true; _items.clear(); _offset = 0; _hasMore = true; });
    final list = await provider.loadMoviesPaged(status: status, offset: 0);
    if (!mounted) return;
    setState(() {
      _items.addAll(list);
      _offset = list.length;
      _hasMore = list.length >= 20;
      _isLoading = false;
    });
  }

  Future<void> _loadMore() async {
    if (_isLoading || !_hasMore) return;
    setState(() => _isLoading = true);
    final provider = context.read<AppProvider>();
    final status = _statusMap[provider.movieStatusIndex] ?? 'watched';
    final list = await provider.loadMoviesPaged(status: status, offset: _offset);
    if (!mounted) return;
    setState(() {
      _items.addAll(list);
      _offset += list.length;
      _hasMore = list.length >= 20;
      _isLoading = false;
    });
  }

  Future<void> _refresh() async {
    final provider = context.read<AppProvider>();
    await provider.loadMovies();
    await _loadFirst();
  }

  @override
  Widget build(BuildContext context) {
    final colors = Theme.of(context).colorScheme;
    return Column(
      children: [
        const MovieStatusBar(),
        Divider(height: 0.5, thickness: 0.5, color: colors.outline),
        Expanded(child: _buildBody(context)),
      ],
    );
  }

  Widget _buildBody(BuildContext context) {
    final colors = Theme.of(context).colorScheme;
    return Consumer<AppProvider>(
      builder: (context, provider, _) {
        // 状态切换时重新加载（跳过首次未初始化的情况）
        if (_initialized && provider.movieStatusIndex != _lastStatusIndex) {
          _lastStatusIndex = provider.movieStatusIndex;
          WidgetsBinding.instance.addPostFrameCallback((_) => _loadFirst());
        }

        if (_items.isEmpty && _isLoading) return _buildSkeleton();

        if (_items.isEmpty) {
          return RefreshIndicator(
            onRefresh: _refresh,
            color: colors.primary,
            backgroundColor: colors.surface,
            child: ListView(
              physics: const AlwaysScrollableScrollPhysics(),
              children: [_buildEmptyState(context, provider.movieStatusIndex)],
            ),
          );
        }

        return RefreshIndicator(
          onRefresh: _refresh,
          color: colors.primary,
          backgroundColor: colors.surface,
          child: _layoutStyle == 1 ? _buildListView() : _buildGridView(),
        );
      },
    );
  }

  Widget _buildGridView() {
    return GridView.builder(
      controller: _scrollController,
      padding: const EdgeInsets.fromLTRB(16, 16, 16, 100),
      gridDelegate: const SliverGridDelegateWithFixedCrossAxisCount(
        crossAxisCount: 3, childAspectRatio: 0.55, crossAxisSpacing: 12, mainAxisSpacing: 16,
      ),
      itemCount: _items.length + (_hasMore ? 1 : 0),
      itemBuilder: (context, index) {
        if (index >= _items.length) return _buildLoadMoreIndicator();
        return MovieListItem(movie: _items[index]);
      },
    );
  }

  Widget _buildListView() {
    return ListView.builder(
      controller: _scrollController,
      padding: const EdgeInsets.fromLTRB(12, 8, 12, 100),
      itemCount: _items.length + (_hasMore ? 1 : 0),
      itemBuilder: (context, index) {
        if (index >= _items.length) return _buildLoadMoreIndicator();
        return _buildListCard(_items[index]);
      },
    );
  }

  Widget _buildLoadMoreIndicator() {
    return Padding(
      padding: const EdgeInsets.symmetric(vertical: 20),
      child: Center(
        child: _isLoading
            ? SizedBox(width: 20, height: 20, child: CircularProgressIndicator(strokeWidth: 2, color: Theme.of(context).colorScheme.primary))
            : Text('没有更多了', style: TextStyle(fontSize: 12, color: Theme.of(context).colorScheme.onSurface.withValues(alpha: 0.3))),
      ),
    );
  }

  Widget _buildListCard(Movie movie) {
    final colors = Theme.of(context).colorScheme;
    return GestureDetector(
      onTap: () => Navigator.pushNamed(context, '/movie-detail', arguments: movie),
      onLongPress: () => _showDeleteDialog(context, movie),
      child: Container(
        margin: const EdgeInsets.only(bottom: 8),
        padding: const EdgeInsets.all(12),
        decoration: BoxDecoration(color: colors.surfaceContainerHigh, borderRadius: BorderRadius.circular(12)),
        child: Row(children: [
          Container(
            width: 48, height: 64,
            decoration: BoxDecoration(color: colors.outlineVariant, borderRadius: BorderRadius.circular(6)),
            clipBehavior: Clip.antiAlias,
            child: movie.posterPath != null && movie.posterPath!.isNotEmpty
                ? FadeInLocalImage(path: movie.posterPath, fit: BoxFit.cover,
                    errorWidget: Icon(Icons.movie_outlined, size: 22, color: colors.onSurface.withValues(alpha: 0.25)))
                : Icon(Icons.movie_outlined, size: 22, color: colors.onSurface.withValues(alpha: 0.25)),
          ),
          const SizedBox(width: 12),
          Expanded(child: Column(crossAxisAlignment: CrossAxisAlignment.start, children: [
            Text(movie.title, maxLines: 1, overflow: TextOverflow.ellipsis,
                style: TextStyle(fontSize: 15, fontWeight: FontWeight.w600, color: colors.onSurface)),
            if (movie.alternateTitles.isNotEmpty) ...[
              const SizedBox(height: 3),
              Text(movie.alternateTitles.take(2).join('、'), maxLines: 1, overflow: TextOverflow.ellipsis,
                  style: TextStyle(fontSize: 12, color: colors.onSurface.withValues(alpha: 0.35))),
            ],
            const SizedBox(height: 6),
            if (movie.rating != null) AnimatedStarRating(rating: movie.rating!, starSize: 12, showNumber: true)
            else const SizedBox(height: 14),
          ])),
          const SizedBox(width: 8),
          Icon(Icons.chevron_right, color: colors.onSurface.withValues(alpha: 0.2), size: 20),
        ]),
      ),
    );
  }

  void _showDeleteDialog(BuildContext context, Movie movie) {
    final colors = Theme.of(context).colorScheme;
    showDialog(
      context: context,
      builder: (ctx) => AlertDialog(
        backgroundColor: colors.surface, elevation: 0,
        shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(12)),
        title: Text('确认删除', style: TextStyle(fontSize: 18, fontWeight: FontWeight.w600, color: colors.onSurface)),
        content: Text('确定要删除《${movie.title}》吗？删除后可在回收站恢复。',
            style: TextStyle(fontSize: 14, color: colors.onSurface.withValues(alpha: 0.6), height: 1.5)),
        actions: [
          TextButton(onPressed: () => Navigator.pop(ctx),
              child: Text('取消', style: TextStyle(color: colors.onSurface.withValues(alpha: 0.6)))),
          ElevatedButton(
            onPressed: () async {
              await context.read<AppProvider>().removeMovie(movie.id);
              Navigator.pop(ctx);
              _loadFirst();
            },
            style: ElevatedButton.styleFrom(backgroundColor: colors.error, foregroundColor: colors.onError, elevation: 0,
                shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(8)),
                padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 8)),
            child: const Text('删除'),
          ),
        ],
        actionsPadding: const EdgeInsets.symmetric(horizontal: 16, vertical: 12),
      ),
    );
  }

  Widget _buildSkeleton() => _layoutStyle == 1 ? _buildListSkeleton() : const MovieSkeletonGrid();

  Widget _buildListSkeleton() {
    final colors = Theme.of(context).colorScheme;
    return ListView.builder(
      padding: const EdgeInsets.fromLTRB(12, 8, 12, 100), itemCount: 6,
      itemBuilder: (_, __) => Container(
        margin: const EdgeInsets.only(bottom: 8), padding: const EdgeInsets.all(12),
        decoration: BoxDecoration(color: colors.surfaceContainerHigh, borderRadius: BorderRadius.circular(12)),
        child: const Row(children: [
          ShimmerSkeleton(width: 48, height: 64, borderRadius: 6), SizedBox(width: 12),
          Expanded(child: Column(crossAxisAlignment: CrossAxisAlignment.start, children: [
            ShimmerSkeleton(width: 160, height: 16), SizedBox(height: 6),
            ShimmerSkeleton(width: 100, height: 12), SizedBox(height: 6),
            ShimmerSkeleton(width: 70, height: 12),
          ])),
          SizedBox(width: 8), ShimmerSkeleton(width: 20, height: 20, borderRadius: 10),
        ]),
      ),
    );
  }

  Widget _buildEmptyState(BuildContext context, int statusIndex) {
    final colors = Theme.of(context).colorScheme;
    final statusText = ['已看', '在看', '想看'][statusIndex];
    return Center(child: Column(mainAxisAlignment: MainAxisAlignment.center, children: [
      Container(width: 80, height: 80,
          decoration: BoxDecoration(color: colors.surfaceContainerHighest, borderRadius: BorderRadius.circular(20)),
          child: Icon(Icons.movie_outlined, size: 40, color: colors.onSurface.withValues(alpha: 0.25))),
      const SizedBox(height: 20),
      Text('暂无$statusText的影片', style: TextStyle(fontSize: 16, color: colors.onSurface.withValues(alpha: 0.4))),
      const SizedBox(height: 24),
      InkWell(
        onTap: () {
          final statusMap = {0: 'watched', 1: 'watching', 2: 'want_to_watch'};
          Navigator.pushNamed(context, '/movie-form', arguments: {'initialStatus': statusMap[statusIndex]!});
        },
        child: Container(
          padding: const EdgeInsets.symmetric(horizontal: 24, vertical: 12),
          decoration: BoxDecoration(color: colors.primary, borderRadius: BorderRadius.circular(8)),
          child: Text('添加记录', style: TextStyle(fontSize: 14, fontWeight: FontWeight.w500, color: colors.onPrimary)),
        ),
      ),
    ]));
  }
}
