import 'dart:async';

import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:go_router/go_router.dart';

import '../../core/log/action_logger.dart';
import '../../core/theme/app_theme.dart';
import '../../models/video_item.dart';
import '../../providers/auth_provider.dart';
import '../../providers/feed_provider.dart';
import '../../providers/search_provider.dart';
import '../../router.dart';
import '../feed/widgets/comment_sheet.dart';
import '../feed/widgets/feed_overlays.dart';
import '../feed/widgets/feed_video_page.dart';

/// 搜索结果播放页：复用 Feed 播放器池的「第 6 个策略」，
/// 支持上下滑切上/下一个视频、双击点赞、长按倍速/分享、评论等完整体验。
/// 数据由搜索页 injectItems 注入，不走网络刷新；触底加载更多由搜索 provider 完成后再注入。
class SearchFeedScreen extends ConsumerStatefulWidget {
  const SearchFeedScreen({super.key});

  @override
  ConsumerState<SearchFeedScreen> createState() => _SearchFeedScreenState();
}

class _SearchFeedScreenState extends ConsumerState<SearchFeedScreen>
    with WidgetsBindingObserver, RouteAware {
  static const _strategy = FeedStrategy.search;
  final PageController _pageController = PageController();
  StreamSubscription<FeedEvent>? _eventSub;

  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addObserver(this);
    ActionLogger.I.log('route_enter', page: '/search/feed');
    _eventSub = ref
        .read(feedProvider(_strategy).notifier)
        .events
        .listen(_handleEvent);
    // 注入完成后跳到目标 index（数据由搜索页在 push 前 injectItems 灌入）
    WidgetsBinding.instance.addPostFrameCallback((_) {
      if (!mounted) return;
      final idx = ref.read(feedProvider(_strategy)).currentIndex;
      if (idx > 0 && _pageController.hasClients) {
        _pageController.jumpToPage(idx);
      }
    });
  }

  @override
  void didChangeDependencies() {
    super.didChangeDependencies();
    final route = ModalRoute.of(context);
    if (route is PageRoute) routeObserver.subscribe(this, route);
  }

  /// 本页之上又 push 了新路由（评论/分享/登录等）：停掉搜索池，避免返回路径复杂时残留声音
  @override
  void didPushNext() {
    ref.read(feedProvider(_strategy).notifier).pool.stopAll();
  }

  /// 上层路由 pop 回本页：恢复播放
  @override
  void didPopNext() {
    if (!mounted) return;
    // 游客额度已用尽：保持锁定，不恢复播放
    if (ref.read(guestLockedProvider)) return;
    final notifier = ref.read(feedProvider(_strategy).notifier);
    unawaited(() async {
      await notifier.pool.resume();
      await notifier.rebindCurrent();
    }());
  }

  @override
  void dispose() {
    ActionLogger.I.log('route_exit', page: '/search/feed');
    WidgetsBinding.instance.removeObserver(this);
    routeObserver.unsubscribe(this);
    _eventSub?.cancel();
    // 离开搜索播放：直接停掉搜索策略的池（断音 + 断缓存下载）。
    ref.read(feedProvider(_strategy).notifier).pool.stopAll();
    _pageController.dispose();
    super.dispose();
  }

  /// App 退后台挂起、回前台从断点续播
  @override
  void didChangeAppLifecycleState(AppLifecycleState state) {
    final notifier = ref.read(feedProvider(_strategy).notifier);
    if (state == AppLifecycleState.paused) {
      notifier.pool.suspend();
    } else if (state == AppLifecycleState.inactive) {
      notifier.pool.pauseCurrent();
    } else if (state == AppLifecycleState.resumed) {
      // 本页不可见时（压在登录页/评论页下）不恢复播放；游客锁定时也不恢复
      if ((ModalRoute.of(context)?.isCurrent ?? false) &&
          !ref.read(guestLockedProvider)) {
        unawaited(() async {
          await notifier.pool.resume();
          await notifier.rebindCurrent();
        }());
      }
    }
  }

  void _handleEvent(FeedEvent event) {
    if (!mounted) return;
    switch (event) {
      case FeedToastEvent(:final message):
        showTopToast(context, message);
      case FeedGuestLimitEvent():
        showGuestLimitDialog(context);
      case FeedPointsInsufficientEvent(:final points):
        showPointsInsufficientDialog(context, points);
    }
  }

  /// 打开评论弹层：打开期间暂停当前播放，关闭后恢复
  Future<void> _openComments(VideoItem item) async {
    final notifier = ref.read(feedProvider(_strategy).notifier);
    notifier.pool.pauseCurrent();
    await showCommentSheet(
      context,
      videoId: item.videoId,
      onCountChanged: (delta) =>
          notifier.adjustCommentCount(item.videoId, delta),
    );
    if (mounted) notifier.pool.playCurrent();
  }

  @override
  Widget build(BuildContext context) {
    final state = ref.watch(feedProvider(_strategy));
    final notifier = ref.read(feedProvider(_strategy).notifier);
    final keyword = ref.watch(searchProvider).keyword;
    final guestLocked = ref.watch(guestLockedProvider);

    // 登录成功后解除游客锁并恢复当前视频
    ref.listen<AuthState>(authProvider, (previous, next) {
      if (next.isLoggedIn && ref.read(guestLockedProvider)) {
        ref.read(guestLockedProvider.notifier).state = false;
        unawaited(ref.read(feedProvider(_strategy).notifier).rebindCurrent());
      }
    });

    return PopScope(
      // 系统返回键/手势也要先停搜索池再放行 pop
      onPopInvokedWithResult: (didPop, _) {
        if (didPop) {
          ref.read(feedProvider(_strategy).notifier).pool.stopAll();
        }
      },
      child: Scaffold(
        backgroundColor: Colors.black,
        body: Stack(
        children: [
          // 内容区
          if (state.items.isEmpty)
            const Center(
              child: Text('暂无视频', style: TextStyle(color: AppColors.textSecondary)),
            )
          else
            NotificationListener<ScrollNotification>(
              onNotification: (n) {
                // 手指开始拖动即静音，避免划动过程中上一个视频仍在出声
                if (n is ScrollStartNotification && n.dragDetails != null) {
                  notifier.pool.pauseCurrent();
                }
                return false;
              },
              child: PageView.builder(
                controller: _pageController,
                scrollDirection: Axis.vertical,
                itemCount: state.items.length,
                onPageChanged: notifier.onPageChanged,
                itemBuilder: (context, index) {
                  final item = state.items[index];
                  return FeedVideoPage(
                    key: ValueKey(item.videoId),
                    item: item,
                    slotIndex: notifier.pool.slotOf(index),
                    pool: notifier.pool,
                    isCurrent: index == state.currentIndex,
                    onLike: notifier.toggleLike,
                    onFavorite: notifier.toggleFavorite,
                    onComment: _openComments,
                    onReturnFromPlayer: notifier.rebindCurrent,
                  );
                },
              ),
            ),

          // 顶部：返回按钮 + 搜索关键词
          SafeArea(
            child: Padding(
              padding: const EdgeInsets.symmetric(horizontal: 4, vertical: 4),
              child: Row(
                children: [
                  IconButton(
                    icon: const Icon(Icons.arrow_back_ios,
                        size: 20, color: Colors.white),
                    onPressed: () {
                      // 先停搜索池再 pop，避免依赖 dispose 时机导致声音残留
                      ref.read(feedProvider(_strategy).notifier).pool.stopAll();
                      context.pop();
                    },
                  ),
                  if (keyword.isNotEmpty)
                    Expanded(
                      child: Text(
                        keyword,
                        maxLines: 1,
                        overflow: TextOverflow.ellipsis,
                        style: const TextStyle(
                          fontSize: 15,
                          color: Colors.white,
                          shadows: [Shadow(color: Colors.black54, blurRadius: 4)],
                        ),
                      ),
                    ),
                ],
              ),
            ),
          ),

          // 底部：免费剩余次数提示条（≤3 时显示）
          Positioned(
            left: 0,
            right: 0,
            bottom: 0,
            child: FreeQuotaBanner(remaining: state.freeRemainingToday),
          ),

          // 游客免费额度已用尽：全屏锁（必须登录，点「再逛逛」也无法继续观看）
          if (guestLocked) const Positioned.fill(child: GuestLockOverlay()),
        ],
        ),
      ),
    );
  }
}