// Author: fruit.com.cn

import 'dart:async';

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

import '../../../core/data/models/category_ranking.dart';
import '../../../core/data/models/drama.dart';
import '../../../core/data/services/category_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/drama_grid_skeleton.dart';
import '../../../core/widgets/empty_state.dart';
import '../../../l10n/app_localizations.dart';
import '../../ranking/widgets/ranking_drama_row.dart';

/// 榜单页顶部暗红光晕，向下淡入纯黑（与剧场榜单页一致）。
const BoxDecoration _rankingBackdrop = BoxDecoration(
  gradient: LinearGradient(
    begin: Alignment.topCenter,
    end: Alignment.bottomCenter,
    colors: [
      AppColors.followingGlow,
      AppColors.followingGlowMid,
      AppColors.appBackground,
    ],
    stops: [0, 0.14, 0.3],
  ),
);

/// 推荐榜频道：服务端排名快照，统一行布局，名次角标压在封面左上角。
class HomeRankingDramas extends StatefulWidget {
  const HomeRankingDramas({
    super.key,
    required this.categoryId,
    required this.onOpenDrama,
    this.topPadding = AppDimens.spaceLg,
  });

  final String categoryId;
  final ValueChanged<Drama> onOpenDrama;
  final double topPadding;

  @override
  State<HomeRankingDramas> createState() => _HomeRankingDramasState();
}

class _HomeRankingDramasState extends State<HomeRankingDramas> {
  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addPostFrameCallback((_) => _ensureLoaded());
  }

  @override
  void didUpdateWidget(HomeRankingDramas oldWidget) {
    super.didUpdateWidget(oldWidget);
    if (oldWidget.categoryId != widget.categoryId) _ensureLoaded();
  }

  void _ensureLoaded() {
    if (!mounted) return;
    final controller = context.read<CategoryController>();
    final slot = controller.rankingSlotOf(widget.categoryId);
    if (slot.loading || slot.ranking != null) return;
    unawaited(controller.openRanking(widget.categoryId));
  }

  @override
  Widget build(BuildContext context) {
    final controller = context.watch<CategoryController>();
    final slot = controller.rankingSlotOf(widget.categoryId);
    final entries = slot.ranking?.entries ?? const <CategoryRankingEntry>[];
    if (slot.loading && entries.isEmpty) {
      return const DecoratedBox(
        key: Key('home-ranking-surface'),
        decoration: _rankingBackdrop,
        child: DramaGridSkeleton(
          key: Key('home-ranking-skeleton'),
          columns: 3,
          horizontalPadding: AppDimens.feedPageHorizontal,
          crossAxisSpacing: AppDimens.homeGridGap,
          mainAxisSpacing: AppDimens.homeGridRowGap,
        ),
      );
    }
    return DecoratedBox(
      key: const Key('home-ranking-surface'),
      decoration: _rankingBackdrop,
      child: Material(
        type: MaterialType.transparency,
        child: AppPullToRefresh(
          key: const Key('home-ranking-refresh'),
          onRefresh: () => controller.openRanking(widget.categoryId),
          child: _content(context, entries, slot.error),
        ),
      ),
    );
  }

  Widget _content(
    BuildContext context,
    List<CategoryRankingEntry> entries,
    Object? error,
  ) {
    final l10n = AppLocalizations.of(context)!;
    if (entries.isEmpty) {
      return CustomScrollView(
        key: PageStorageKey<String>('home-ranking-scroll-${widget.categoryId}'),
        physics: AppPullToRefresh.physics,
        slivers: [
          SliverFillRemaining(
            hasScrollBody: false,
            child: EmptyState(
              key: Key(
                error == null ? 'home-ranking-empty' : 'home-ranking-error',
              ),
              icon: error == null
                  ? Icons.leaderboard_outlined
                  : Icons.cloud_off_rounded,
              title: error == null ? l10n.emptyContent : l10n.catalogError,
              actionLabel: error == null ? null : l10n.retry,
              onAction: error == null
                  ? null
                  : () => unawaited(
                      context.read<CategoryController>().openRanking(
                        widget.categoryId,
                      ),
                    ),
              stretchContent: true,
            ),
          ),
        ],
      );
    }
    return CustomScrollView(
      key: PageStorageKey<String>('home-ranking-scroll-${widget.categoryId}'),
      physics: AppPullToRefresh.physics,
      slivers: [
        SliverPadding(
          padding: EdgeInsets.fromLTRB(
            AppDimens.feedPageHorizontal,
            widget.topPadding,
            AppDimens.feedPageHorizontal,
            AppDimens.spaceXl,
          ),
          sliver: SliverList.separated(
            itemCount: entries.length,
            itemBuilder: (context, index) => _row(entries[index]),
            separatorBuilder: (_, _) => const Divider(
              height: AppDimens.mineGridDividerWidth,
              thickness: AppDimens.mineGridDividerWidth,
              color: AppColors.border,
            ),
          ),
        ),
      ],
    );
  }

  Widget _row(CategoryRankingEntry entry) {
    return Padding(
      padding: const EdgeInsets.symmetric(vertical: AppDimens.spaceSm),
      child: RankingDramaRow(
        rank: entry.rank,
        drama: entry.drama,
        onTap: () => widget.onOpenDrama(entry.drama),
      ),
    );
  }
}