// Author: fruit.com.cn

import 'dart:async';

import 'package:flutter/material.dart';
import 'package:provider/provider.dart';

import '../../core/data/models/drama.dart';
import '../../core/data/services/catalog_controller.dart';
import '../../core/theme/app_colors.dart';
import '../../core/theme/app_dimens.dart';
import '../../core/widgets/app_pull_to_refresh.dart';
import '../../core/widgets/empty_state.dart';
import '../../core/widgets/paged_local_list.dart';
import '../../core/widgets/plain_page_scaffold.dart';
import '../../l10n/app_localizations.dart';
import '../player/open_player.dart';
import 'widgets/ranking_drama_row.dart';

const int _topCount = 50;
const double _loadMoreThreshold = 200;

/// 剧场榜单页：统一行布局，名次角标压在封面左上角，右侧字段无数据不展示。
class RankingPage extends StatefulWidget {
  const RankingPage({super.key, this.embedded = false});

  final bool embedded;

  @override
  State<RankingPage> createState() => _RankingPageState();
}

class _RankingPageState extends State<RankingPage> {
  final ScrollController _scroll = ScrollController();
  PagedLocalListController<Drama>? _pager;
  bool _refreshing = false;

  @override
  void didChangeDependencies() {
    super.didChangeDependencies();
    if (_pager != null) return;
    _pager = PagedLocalListController<Drama>(
      items: _ranked(context.read<CatalogController>().dramas),
    )..addListener(_rebuild);
  }

  @override
  void dispose() {
    _pager
      ?..removeListener(_rebuild)
      ..dispose();
    _scroll.dispose();
    super.dispose();
  }

  void _rebuild() {
    if (mounted) setState(() {});
  }

  List<Drama> _ranked(List<Drama> source) {
    final dramas = [...source]
      ..sort((a, b) => b.viewCount.compareTo(a.viewCount));
    return dramas.take(_topCount).toList(growable: false);
  }

  Future<void> _refresh() async {
    if (_refreshing) return;
    _refreshing = true;
    try {
      final catalog = context.read<CatalogController>();
      await catalog.refresh();
      if (!mounted) return;
      _pager!.replaceAll(_ranked(catalog.dramas));
      if (_scroll.hasClients) {
        _scroll.jumpTo(_scroll.position.minScrollExtent);
      }
    } finally {
      _refreshing = false;
    }
  }

  bool _onScroll(ScrollNotification notification) {
    if (notification.depth != 0 || _refreshing) return false;
    if (notification.metrics.extentAfter > _loadMoreThreshold) return false;
    if (notification is ScrollUpdateNotification ||
        notification is ScrollEndNotification ||
        notification is OverscrollNotification) {
      unawaited(_pager!.loadMore());
    }
    return false;
  }

  @override
  Widget build(BuildContext context) {
    final l10n = AppLocalizations.of(context)!;
    final catalog = context.watch<CatalogController>();
    final top = _pager!.visibleItems;
    final content = NotificationListener<ScrollNotification>(
      onNotification: _onScroll,
      child: AppPullToRefresh(
        key: const Key('ranking-refresh'),
        onRefresh: _refresh,
        child: ListView(
          key: const Key('ranking-list'),
          controller: _scroll,
          physics: AppPullToRefresh.physics,
          padding: const EdgeInsets.only(top: 8, bottom: 24),
          children: top.isEmpty
              ? [_emptyState(l10n, catalog)]
              : [
                  if (widget.embedded) _intro(l10n),
                  const SizedBox(height: AppDimens.spaceMd),
                  for (var index = 0; index < top.length; index++) ...[
                    Padding(
                      padding: const EdgeInsets.symmetric(
                        horizontal: AppDimens.feedPageHorizontal,
                        vertical: AppDimens.spaceSm,
                      ),
                      child: RankingDramaRow(
                        rank: index + 1,
                        drama: top[index],
                        onTap: () => unawaited(
                          playDramaFromCatalog(context, top[index]),
                        ),
                      ),
                    ),
                    if (index != top.length - 1)
                      const Padding(
                        padding: EdgeInsets.symmetric(
                          horizontal: AppDimens.feedPageHorizontal,
                        ),
                        child: Divider(
                          height: AppDimens.mineGridDividerWidth,
                          thickness: AppDimens.mineGridDividerWidth,
                          color: AppColors.border,
                        ),
                      ),
                  ],
                  PagedLoadFooter(
                    loading: _pager!.loading,
                    hasMore: _pager!.hasMore,
                    hasItems: _pager!.visibleItems.isNotEmpty,
                    loadMoreKey: const Key('ranking-load-more'),
                  ),
                ],
        ),
      ),
    );
    if (widget.embedded) {
      return KeyedSubtree(key: const Key('ranking-page'), child: content);
    }
    return PlainPageScaffold(
      pageKey: const Key('ranking-page'),
      backKey: const Key('ranking-back'),
      title: l10n.topCharts,
      subtitle: l10n.rankingSubtitle,
      child: content,
    );
  }

  Widget _intro(AppLocalizations l10n) {
    return Padding(
      padding: const EdgeInsets.symmetric(
        horizontal: AppDimens.feedPageHorizontal,
      ),
      child: Column(
        key: const Key('ranking-hero'),
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Text(
            l10n.topCharts,
            style: const TextStyle(
              color: AppColors.textPrimary,
              fontSize: AppDimens.rankingHeroTitle,
              fontWeight: FontWeight.w700,
            ),
          ),
          const SizedBox(height: 2),
          Text(
            l10n.rankingSubtitle,
            style: const TextStyle(
              color: AppColors.textTertiary,
              fontSize: AppDimens.rankingHeroSubtitle,
            ),
          ),
        ],
      ),
    );
  }

  Widget _emptyState(AppLocalizations l10n, CatalogController catalog) {
    final theme = Theme.of(context);
    return SizedBox(
      height: 420,
      child: Theme(
        data: theme.copyWith(
          colorScheme: theme.colorScheme.copyWith(
            onSurface: AppColors.textTertiary,
          ),
        ),
        child: EmptyState(
          key: Key(catalog.error == null ? 'ranking-empty' : 'ranking-error'),
          icon: catalog.error == null
              ? Icons.leaderboard_outlined
              : Icons.cloud_off_rounded,
          title: catalog.error == null ? l10n.noStories : l10n.catalogError,
          actionLabel: catalog.error == null ? null : l10n.retry,
          onAction: catalog.error == null ? null : () => unawaited(_refresh()),
          stretchContent: true,
        ),
      ),
    );
  }
}