// Author: fruit.com.cn

import 'dart:async';

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

import '../../core/data/models/watch_record.dart';
import '../../core/data/services/favorite_controller.dart';
import '../../core/data/services/watch_records_controller.dart';
import '../../core/formatting/error_text.dart';
import '../../core/theme/app_colors.dart';
import '../../core/theme/app_dimens.dart';
import '../../core/widgets/empty_state.dart';
import '../../l10n/app_localizations.dart';
import '../player/open_player.dart';
import 'following_grid_card.dart';
import 'following_paged_grid.dart';
import 'widgets/continue_watching_banner.dart';

/// 追剧编辑中的选中状态。
class FollowingFavoriteSelection {
  const FollowingFavoriteSelection({
    required this.editing,
    required this.selected,
    required this.onToggle,
  });

  final ValueListenable<bool> editing;
  final ValueListenable<Set<String>> selected;
  final ValueChanged<String> onToggle;
}

/// 追剧列表。编辑时点卡片只切换选中，不进入播放。
class FollowingFavoritesGrid extends StatelessWidget {
  const FollowingFavoritesGrid({
    super.key,
    required this.controller,
    required this.history,
    required this.selection,
    required this.scrollController,
    required this.onGoHome,
    required this.onContinueRecord,
  });

  final FavoriteController controller;
  final WatchRecordsController history;
  final FollowingFavoriteSelection selection;
  final ScrollController scrollController;
  final VoidCallback onGoHome;
  final ValueChanged<WatchRecord> onContinueRecord;

  @override
  Widget build(BuildContext context) {
    return ValueListenableBuilder<bool>(
      valueListenable: selection.editing,
      builder: (context, isEditing, _) {
        return ValueListenableBuilder<Set<String>>(
          valueListenable: selection.selected,
          builder: (context, picked, _) {
            return ListenableBuilder(
              listenable: Listenable.merge([controller, history]),
              builder: (context, _) => _grid(context, isEditing, picked),
            );
          },
        );
      },
    );
  }

  Widget _grid(BuildContext context, bool isEditing, Set<String> picked) {
    final l10n = AppLocalizations.of(context)!;
    final hasFavorites = controller.cards.isNotEmpty;
    final extra = !isEditing && hasFavorites ? 1 : 0;
    return FollowingPagedGrid(
      key: const Key('following-favorites-grid'),
      scrollController: scrollController,
      loading: controller.loading,
      loadingMore: controller.loadingMore,
      hasMore: controller.hasMore,
      hasItems: hasFavorites,
      showInitialLoading: false,
      errorMessage: controller.error == null
          ? null
          : errorText(l10n, controller.error, l10n.favoritesError),
      loadMoreError: controller.loadMoreError == null
          ? null
          : errorText(l10n, controller.loadMoreError, l10n.favoritesError),
      onRefresh: controller.load,
      onLoadMore: controller.loadMore,
      itemCount: controller.cards.length + extra,
      topSlivers: _topSlivers(context),
      empty: EmptyState(
        key: const Key('following-favorites-empty'),
        icon: Icons.bookmark_border_rounded,
        title: l10n.noFavoritesYet,
      ),
      itemBuilder: (context, index) => _item(context, index, isEditing, picked),
    );
  }

  List<Widget> _topSlivers(BuildContext context) {
    final l10n = AppLocalizations.of(context)!;
    final continueRecord = _continueRecord();
    return [
      if (continueRecord != null)
        SliverToBoxAdapter(
          child: Padding(
            padding: const EdgeInsets.fromLTRB(
              AppDimens.feedPageHorizontal,
              4,
              AppDimens.feedPageHorizontal,
              0,
            ),
            child: ContinueWatchingBanner(
              record: continueRecord,
              languageCode: Localizations.localeOf(context).languageCode,
              onTap: () => onContinueRecord(continueRecord),
            ),
          ),
        ),
      SliverToBoxAdapter(
        child: Padding(
          padding: const EdgeInsets.fromLTRB(
            AppDimens.feedPageHorizontal,
            AppDimens.followingSectionTopGap,
            AppDimens.feedPageHorizontal,
            AppDimens.followingSectionBottomGap,
          ),
          child: Row(
            crossAxisAlignment: CrossAxisAlignment.end,
            children: [
              Text(
                l10n.favoriteDramas,
                style: const TextStyle(
                  color: AppColors.textPrimary,
                  fontSize: AppDimens.followingSectionTitleFont,
                  fontWeight: FontWeight.w400,
                ),
              ),
              const Spacer(),
              Padding(
                padding: const EdgeInsets.only(bottom: 2),
                child: Text(
                  l10n.totalDramasCount(controller.total),
                  style: const TextStyle(
                    color: AppColors.textTabInactive,
                    fontSize: AppDimens.followingSectionCountFont,
                  ),
                ),
              ),
            ],
          ),
        ),
      ),
    ];
  }

  /// 最近一条观看记录（records 已按最近观看排序，与观看历史页首条一致）。
  WatchRecord? _continueRecord() {
    return history.records.isEmpty ? null : history.records.first;
  }

  Widget _item(
    BuildContext context,
    int index,
    bool isEditing,
    Set<String> picked,
  ) {
    final l10n = AppLocalizations.of(context)!;
    if (index == controller.cards.length) {
      return FollowingAddCard(onTap: onGoHome);
    }
    final drama = controller.cards[index];
    final record = history.recordForDrama(drama.id);
    final episode = drama.episodes.isEmpty ? 1 : drama.episodes.first.number;
    final watchedEpisode = record?.episodeNumber ?? 0;
    final total = drama.episodeCount;
    final subtitle = watchedEpisode > 0 && total > 0
        ? l10n.watchedEpisodeTotal(watchedEpisode, total)
        : l10n.favoriteEpisodeProgress(episode, total);
    return FollowingGridCard(
      dramaId: drama.id,
      title: drama.localizedTitle(Localizations.localeOf(context).languageCode),
      posterUrl: drama.posterUrl,
      viewCount: drama.viewCount,
      editing: isEditing,
      selected: isEditing ? picked.contains(drama.id) : null,
      subtitle: subtitle,
      // TODO(backend): Drama 增加 hasUpdate / latestEpisodeNumber / isFinished
      // 字段后，在此传 updateBadge（l10n.hasUpdateBadge）、红色更新副标题
      // （l10n.updatedToEpisode）或灰色完结副标题（l10n.finishedAllEpisodes）。
      onTap: () => _openOrToggle(context, drama.id, isEditing),
    );
  }

  void _openOrToggle(BuildContext context, String dramaId, bool isEditing) {
    if (isEditing) {
      selection.onToggle(dramaId);
      return;
    }
    final drama = controller.cards.firstWhere((item) => item.id == dramaId);
    unawaited(playDramaFromCatalog(context, drama));
  }
}