import 'dart:async';
import 'dart:math' show max;

import 'package:cached_network_image/cached_network_image.dart';
import 'package:client_proxy_framework/client_proxy_framework.dart';
import 'package:flutter/material.dart';
import 'package:google_fonts/google_fonts.dart';
import 'package:video_player/video_player.dart';

import '../../core/auth/auth_service.dart';
import '../../core/open_purchase_store.dart';
import '../../core/user/user_state.dart';
import '../../core/video_file_cache.dart';
import '../../design/pencil_theme.dart';
import '../../widgets/pencil_chrome.dart';
import '../generate/generate_screen.dart';

/// 首页 Create Now 上方展示的预估积分：**480p 档**（与 [GenerateScreen] 选 480p 时一致）。
int _homeCostDisplay480p(ExtConfigItem? t) {
  if (t == null) return 0;
  if (t.cost480p != null && t.cost480p! > 0) return t.cost480p!;
  int effective720() {
    if (t.cost720p != null && t.cost720p! > 0) return t.cost720p!;
    if (t.cost > 0) return t.cost;
    return 0;
  }

  final h = effective720();
  if (h <= 0) return 0;
  return max(1, (h / 2).round());
}

/// 首页横向 [PageView] 的一页：对应某个顶部分类 [tabIndex]，[item] 为空表示该分类暂无模板占位。
class _FlatHomePage {
  const _FlatHomePage({required this.tabIndex, this.item});

  final int tabIndex;
  final ExtConfigItem? item;
}

/// `bi8Au` FunyMee Home — 底层 `assets/images/home_background.png`，模板图为全屏 [PageView] 叠在其上。
/// - `go_run`（[ExtConfigData.showVideoMenu]）为 `true` 时：顶栏为**分类** Tab；多分类时用**单层** [PageView]，
///   将各分类模板**展平**为连续页，横滑可连贯切换分类（整页动画），避免嵌套横向 PageView 的手势冲突。
/// - 非视频模式：[ExtConfigData.items] 每一项对应一页。
class HomeScreen extends StatefulWidget {
  const HomeScreen({super.key});

  @override
  State<HomeScreen> createState() => _HomeScreenState();
}

class _HomeScreenState extends State<HomeScreen> {
  /// 展平后 [PageView] 的当前页下标（跨分类连续）。
  int _selectedIndex = 0;
  final PageController _pageController = PageController();

  final ScrollController _categoryTabScrollController = ScrollController();

  /// 顶部分类 Tab 每项的 key，用于 [Scrollable.ensureVisible] 把选中项滚到中间。
  final List<GlobalKey> _categoryTabItemKeys = [];

  /// 上次已尝试居中的分类下标，避免重复调度。
  int _lastCenteredCategoryTabIndex = -1;

  int _lastCategoryTabBarCount = 0;

  List<ExtConfigItem> _visibleExtItems(ExtConfigData? ext) =>
      ext?.items.where((e) => e.isUsableOnHome).toList() ?? [];

  /// 指定顶部分类下的模板列表（视频模式用 [VideoHomeSnapshot]；否则为 ext.items）。
  List<ExtConfigItem> _templateItemsForTab(
    ExtConfigData? ext,
    VideoHomeSnapshot video,
    int tabIndex,
  ) {
    final base = _visibleExtItems(ext);
    if (ext?.showVideoMenu != true) return base;
    if (video.tabs.isEmpty) return base;
    final ti = tabIndex.clamp(0, video.tabs.length - 1);
    final tab = video.tabs[ti];
    if (tab.isImages) return base;
    final id = tab.categoryId!;
    return video.networkItemsByCategoryId[id] ?? [];
  }

  /// 展平为单层 [PageView] 的页序列：多分类时连续滑动即可跨分类；空分类占一页占位。
  List<_FlatHomePage> _buildFlatPages(
    ExtConfigData? ext,
    VideoHomeSnapshot video,
  ) {
    final base = _visibleExtItems(ext);
    if (ext?.showVideoMenu != true || video.tabs.isEmpty) {
      if (base.isEmpty) return [];
      return [for (final item in base) _FlatHomePage(tabIndex: 0, item: item)];
    }
    final out = <_FlatHomePage>[];
    for (var t = 0; t < video.tabs.length; t++) {
      final items = _templateItemsForTab(ext, video, t);
      if (items.isEmpty) {
        out.add(_FlatHomePage(tabIndex: t, item: null));
      } else {
        for (final item in items) {
          out.add(_FlatHomePage(tabIndex: t, item: item));
        }
      }
    }
    return out;
  }

  static int _firstFlatIndexForTab(List<_FlatHomePage> flat, int tabIndex) {
    for (var i = 0; i < flat.length; i++) {
      if (flat[i].tabIndex == tabIndex) return i;
    }
    return 0;
  }

  bool _currentNetworkTabLoading(VideoHomeSnapshot video) {
    if (video.tabs.isEmpty) return false;
    final ti = VideoHomeRuntime.selectedTabIndex.value
        .clamp(0, video.tabs.length - 1);
    final tab = video.tabs[ti];
    if (tab.isImages) return false;
    final id = tab.categoryId!;
    return video.loadingCategoryIds.contains(id) &&
        !video.networkItemsByCategoryId.containsKey(id);
  }

  /// `go_run` / `need_wait` → [ExtConfigData.showVideoMenu]；仅在为 `true` 时展示顶部分类 Tab 栏。
  bool _showTopTabBar(ExtConfigData? ext) => ext?.showVideoMenu == true;

  void _ensureCategoryTabKeys(int count) {
    while (_categoryTabItemKeys.length < count) {
      _categoryTabItemKeys.add(GlobalKey());
    }
    while (_categoryTabItemKeys.length > count) {
      _categoryTabItemKeys.removeLast();
    }
  }

  /// 将指定下标的顶部分类 Tab 尽量滚到横向列表中间（与 PageView 切换分类联动）。
  void _scrollCategoryTabToCenter(int index) {
    if (index < 0 || index >= _categoryTabItemKeys.length) return;
    final ctx = _categoryTabItemKeys[index].currentContext;
    if (ctx == null) return;
    Scrollable.ensureVisible(
      ctx,
      alignment: 0.5,
      duration: const Duration(milliseconds: 280),
      curve: Curves.easeOutCubic,
    );
  }

  /// 视频模式顶部分类 Tab（与中间区内容独立，无任务时也保持显示）。
  Widget _buildCategoryTabRow(VideoHomeSnapshot video) {
    final catIdx = video.tabs.isEmpty
        ? 0
        : VideoHomeRuntime.selectedTabIndex.value
            .clamp(0, video.tabs.length - 1);
    if (video.tabs.length != _lastCategoryTabBarCount) {
      _lastCategoryTabBarCount = video.tabs.length;
      _lastCenteredCategoryTabIndex = -1;
    }
    _ensureCategoryTabKeys(video.tabs.length);
    if (_lastCenteredCategoryTabIndex != catIdx) {
      _lastCenteredCategoryTabIndex = catIdx;
      WidgetsBinding.instance.addPostFrameCallback((_) {
        if (!mounted) return;
        _scrollCategoryTabToCenter(catIdx);
      });
    }
    return Padding(
      padding: const EdgeInsets.only(top: 6, bottom: 12),
      child: SingleChildScrollView(
        controller: _categoryTabScrollController,
        scrollDirection: Axis.horizontal,
        child: Row(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            for (var i = 0; i < video.tabs.length; i++) ...[
              if (i > 0) ...[
                Text(
                  '|',
                  style: GoogleFonts.inter(
                    fontSize: 14,
                    color: PencilTheme.homeTabDivider,
                  ),
                ),
                const SizedBox(width: 14),
              ],
              GestureDetector(
                key: _categoryTabItemKeys[i],
                behavior: HitTestBehavior.opaque,
                onTap: () => _onCategoryTabTap(i),
                child: Text(
                  video.tabs[i].label,
                  style: GoogleFonts.inter(
                    fontSize: 15,
                    fontWeight: FontWeight.w700,
                    color: i == catIdx
                        ? PencilTheme.underlineGold
                        : PencilTheme.homeTextPrimary,
                  ),
                ),
              ),
              if (i < video.tabs.length - 1) const SizedBox(width: 14),
            ],
          ],
        ),
      ),
    );
  }

  void _clampFlatPage(int flatLength) {
    if (flatLength == 0) return;
    if (_selectedIndex >= flatLength) {
      final next = flatLength - 1;
      WidgetsBinding.instance.addPostFrameCallback((_) {
        if (!mounted) return;
        setState(() => _selectedIndex = next);
        if (_pageController.hasClients) {
          _pageController.jumpToPage(next);
        }
      });
    }
  }

  void _onFlatPageChanged(int i, List<_FlatHomePage> flat) {
    if (i < 0 || i >= flat.length) return;
    final t = flat[i].tabIndex;
    if (VideoHomeRuntime.selectedTabIndex.value != t) {
      VideoHomeRuntime.selectedTabIndex.value = t;
      unawaited(VideoHomeRuntime.ensureTabItems(t));
    }
    setState(() => _selectedIndex = i);
  }

  void _onCategoryTabTap(int tabIndex) {
    if (VideoHomeRuntime.selectedTabIndex.value == tabIndex) return;
    final ext = ExtConfigRuntime.data.value;
    final video = VideoHomeRuntime.snapshot.value;
    final flat = _buildFlatPages(ext, video);
    if (flat.isEmpty) return;
    final idx =
        _firstFlatIndexForTab(flat, tabIndex).clamp(0, flat.length - 1);
    VideoHomeRuntime.selectedTabIndex.value = tabIndex;
    unawaited(VideoHomeRuntime.ensureTabItems(tabIndex));
    setState(() => _selectedIndex = idx);
    if (_pageController.hasClients) {
      _pageController.animateToPage(
        idx,
        duration: const Duration(milliseconds: 280),
        curve: Curves.easeOutCubic,
      );
    }
  }

  @override
  void initState() {
    super.initState();
  }

  @override
  void dispose() {
    _pageController.dispose();
    _categoryTabScrollController.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: Colors.white,
      body: Stack(
        fit: StackFit.expand,
        children: [
          Positioned.fill(
            child: Image.asset(
              'assets/images/home_background.png',
              fit: BoxFit.cover,
              errorBuilder: (_, _, _) {
                return Container(
                  decoration: const BoxDecoration(
                    gradient: LinearGradient(
                      begin: Alignment.topLeft,
                      end: Alignment.bottomRight,
                      colors: [
                        Color(0xFF2A2318),
                        Color(0xFF141210),
                      ],
                    ),
                  ),
                );
              },
            ),
          ),
          Positioned.fill(
            child: ValueListenableBuilder<ExtConfigData?>(
              valueListenable: ExtConfigRuntime.data,
              builder: (context, ext, _) {
                return ValueListenableBuilder<VideoHomeSnapshot>(
                  valueListenable: VideoHomeRuntime.snapshot,
                  builder: (context, video, _) {
                    return ValueListenableBuilder<int>(
                      valueListenable: VideoHomeRuntime.selectedTabIndex,
                      builder: (context, _, _) {
                        return ValueListenableBuilder<bool?>(
                          valueListenable:
                              ExtConfigRuntime.commonInfoSucceeded,
                          builder: (context, ok, _) {
                            final flat = _buildFlatPages(ext, video);
                            _clampFlatPage(flat.length);
                            if (ok == null) {
                              return const SizedBox.shrink();
                            }
                            final videoTabs =
                                ext?.showVideoMenu == true &&
                                    video.tabs.isNotEmpty;
                            if (flat.isEmpty) {
                              if (videoTabs) {
                                return const ColoredBox(
                                  color: Colors.transparent,
                                  child: SizedBox.expand(),
                                );
                              }
                              return const SizedBox.shrink();
                            }
                            return PageView.builder(
                              controller: _pageController,
                              itemCount: flat.length,
                              onPageChanged: (i) {
                                final e = ExtConfigRuntime.data.value;
                                final v = VideoHomeRuntime.snapshot.value;
                                _onFlatPageChanged(i, _buildFlatPages(e, v));
                              },
                              itemBuilder: (context, i) {
                                final fp = flat[i];
                                if (fp.item == null) {
                                  return const ColoredBox(
                                    color: Colors.transparent,
                                    child: SizedBox.expand(),
                                  );
                                }
                                return AnimatedBuilder(
                                  animation: _pageController,
                                  builder: (context, _) {
                                    final page = _pageController.hasClients
                                        ? (_pageController.page ??
                                            _selectedIndex.toDouble())
                                        : _selectedIndex.toDouble();
                                    final videoActive = page.round() == i;
                                    return _HomeItemPageContent(
                                      item: fp.item!,
                                      videoActive: videoActive,
                                    );
                                  },
                                );
                              },
                            );
                          },
                        );
                      },
                    );
                  },
                );
              },
            ),
          ),
          SafeArea(
            bottom: false,
            child: Padding(
              padding: EdgeInsets.only(
                left: 16,
                right: 16,
                bottom: 16 + PencilTheme.mainTabBottomChromeReserve(context),
              ),
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.stretch,
                children: [
                  SizedBox(
                    height: 56,
                    child: Row(
                      mainAxisAlignment: MainAxisAlignment.end,
                      children: [
                        ValueListenableBuilder<int>(
                          valueListenable: UserState.credits,
                          builder: (_, credits, _) {
                            return PencilGlassCreditsPill(
                              amountText: credits.toStringAsFixed(2),
                              onTap: () => openPurchaseStore(context),
                            );
                          },
                        ),
                      ],
                    ),
                  ),
                  ValueListenableBuilder<bool?>(
                    valueListenable: ExtConfigRuntime.commonInfoSucceeded,
                    builder: (context, ok, _) {
                      if (ok != false) return const SizedBox.shrink();
                      return Padding(
                        padding: const EdgeInsets.only(top: 8, bottom: 4),
                        child: Container(
                          padding: const EdgeInsets.symmetric(
                            horizontal: 12,
                            vertical: 10,
                          ),
                          decoration: BoxDecoration(
                            color: Colors.black.withValues(alpha: 0.35),
                            borderRadius: BorderRadius.circular(10),
                            border: Border.all(
                              color: Colors.orangeAccent.withValues(alpha: 0.6),
                            ),
                          ),
                          child: Row(
                            children: [
                              Icon(Icons.cloud_off_rounded,
                                  color: Colors.orange.shade200, size: 20),
                              const SizedBox(width: 8),
                              Expanded(
                                child: Text(
                                  'Config failed to load. Some features may be unavailable. Check the network and restart the app.',
                                  style: GoogleFonts.inter(
                                    fontSize: 12,
                                    height: 1.35,
                                    color: Colors.white.withValues(alpha: 0.92),
                                  ),
                                ),
                              ),
                            ],
                          ),
                        ),
                      );
                    },
                  ),
                  Expanded(
                    child: ValueListenableBuilder<ExtConfigData?>(
                      valueListenable: ExtConfigRuntime.data,
                      builder: (context, ext, _) {
                        return ValueListenableBuilder<VideoHomeSnapshot>(
                          valueListenable: VideoHomeRuntime.snapshot,
                          builder: (context, video, _) {
                            return ValueListenableBuilder<int>(
                              valueListenable:
                                  VideoHomeRuntime.selectedTabIndex,
                              builder: (context, _, _) {
                            return ValueListenableBuilder<bool?>(
                              valueListenable:
                                  ExtConfigRuntime.commonInfoSucceeded,
                              builder: (context, ok, _) {
                            final flat = _buildFlatPages(ext, video);
                            _clampFlatPage(flat.length);
                            final showTabs = _showTopTabBar(ext);
                            final showCategoryTabs =
                                showTabs && video.tabs.isNotEmpty;

                            if (ok == null) {
                              return ValueListenableBuilder<bool>(
                                valueListenable: AuthService.isLoginComplete,
                                builder: (context, loginDone, _) {
                                  // [App] startup overlay already shows a spinner; hide
                                  // this duplicate until the overlay is dismissed.
                                  if (!loginDone) {
                                    return const SizedBox.shrink();
                                  }
                                  return Center(
                                    child: Row(
                                      mainAxisAlignment:
                                          MainAxisAlignment.center,
                                      children: [
                                        SizedBox(
                                          width: 18,
                                          height: 18,
                                          child: CircularProgressIndicator(
                                            strokeWidth: 2,
                                            color: PencilTheme.homeTextPrimary,
                                          ),
                                        ),
                                        const SizedBox(width: 10),
                                        Text(
                                          'Loading config…',
                                          style: GoogleFonts.inter(
                                            fontSize: 14,
                                            fontWeight: FontWeight.w600,
                                            color: PencilTheme.homeTextPrimary,
                                          ),
                                        ),
                                      ],
                                    ),
                                  );
                                },
                              );
                            }

                            if (flat.isEmpty) {
                              Widget loadingRow(String text) {
                                return Row(
                                  mainAxisAlignment: MainAxisAlignment.center,
                                  mainAxisSize: MainAxisSize.min,
                                  children: [
                                    SizedBox(
                                      width: 18,
                                      height: 18,
                                      child: CircularProgressIndicator(
                                        strokeWidth: 2,
                                        color: PencilTheme.homeTextPrimary,
                                      ),
                                    ),
                                    const SizedBox(width: 10),
                                    Text(
                                      text,
                                      style: GoogleFonts.inter(
                                        fontSize: 14,
                                        fontWeight: FontWeight.w600,
                                        color: PencilTheme.homeTextPrimary,
                                      ),
                                    ),
                                  ],
                                );
                              }

                              if (ok == true &&
                                  ext?.showVideoMenu == true &&
                                  video.loading) {
                                if (showCategoryTabs) {
                                  return Column(
                                    crossAxisAlignment:
                                        CrossAxisAlignment.stretch,
                                    children: [
                                      _buildCategoryTabRow(video),
                                      Expanded(
                                        child: IgnorePointer(
                                          child: Center(
                                            child: loadingRow(
                                              'Loading video categories…',
                                            ),
                                          ),
                                        ),
                                      ),
                                    ],
                                  );
                                }
                                return Center(
                                  child: loadingRow(
                                    'Loading video categories…',
                                  ),
                                );
                              }
                              if (ok == true &&
                                  ext?.showVideoMenu == true &&
                                  showCategoryTabs &&
                                  _currentNetworkTabLoading(video)) {
                                return Column(
                                  crossAxisAlignment:
                                      CrossAxisAlignment.stretch,
                                  children: [
                                    _buildCategoryTabRow(video),
                                    Expanded(
                                      child: IgnorePointer(
                                        child: Center(
                                          child: loadingRow(
                                            'Loading category templates…',
                                          ),
                                        ),
                                      ),
                                    ),
                                  ],
                                );
                              }
                              if (showCategoryTabs) {
                                return Column(
                                  crossAxisAlignment:
                                      CrossAxisAlignment.stretch,
                                  children: [
                                    _buildCategoryTabRow(video),
                                    Expanded(
                                      child: IgnorePointer(
                                        child: Center(
                                          child: Text(
                                            ok == false
                                                ? 'No templates (config not ready)'
                                                : 'No templates',
                                            textAlign: TextAlign.center,
                                            style: GoogleFonts.inter(
                                              fontSize: 14,
                                              fontWeight: FontWeight.w600,
                                              color: PencilTheme.homeTextPrimary,
                                            ),
                                          ),
                                        ),
                                      ),
                                    ),
                                  ],
                                );
                              }
                              return Center(
                                child: Text(
                                  ok == false
                                      ? 'No templates (config not ready)'
                                      : 'No templates',
                                  textAlign: TextAlign.center,
                                  style: GoogleFonts.inter(
                                    fontSize: 14,
                                    fontWeight: FontWeight.w600,
                                    color: PencilTheme.homeTextPrimary,
                                  ),
                                ),
                              );
                            }

                            return Column(
                              crossAxisAlignment: CrossAxisAlignment.stretch,
                              children: [
                                if (showCategoryTabs)
                                  _buildCategoryTabRow(video),
                                Expanded(
                                  child: IgnorePointer(
                                    child: SizedBox.expand(),
                                  ),
                                ),
                              ],
                            );
                              },
                            );
                          },
                        );
                      },
                    );
                  },
                ),
                  ),
                  Center(
                    child: ValueListenableBuilder<ExtConfigData?>(
                      valueListenable: ExtConfigRuntime.data,
                      builder: (context, ext, _) {
                        return ValueListenableBuilder<VideoHomeSnapshot>(
                          valueListenable: VideoHomeRuntime.snapshot,
                          builder: (context, video, _) {
                            return AnimatedBuilder(
                              animation: _pageController,
                              builder: (context, _) {
                                final flat = _buildFlatPages(ext, video);
                                final safe = flat.isEmpty
                                    ? 0
                                    : (_pageController.hasClients
                                            ? _pageController.page
                                                    ?.round() ??
                                                _selectedIndex
                                            : _selectedIndex)
                                        .clamp(0, flat.length - 1);
                                final template = flat.isEmpty
                                    ? null
                                    : flat[safe].item;
                                final cost = _homeCostDisplay480p(template);

                                return Column(
                                  mainAxisSize: MainAxisSize.min,
                                  children: [
                                    if (cost > 0) ...[
                                      Text(
                                        '$cost credits',
                                        style: GoogleFonts.inter(
                                          fontSize: 13,
                                          fontWeight: FontWeight.w600,
                                          color: PencilTheme.homeTextPrimary
                                              .withValues(alpha: 0.85),
                                          shadows:
                                              PencilTheme.homeCreditsTextShadows,
                                        ),
                                      ),
                                      const SizedBox(height: 12),
                                    ],
                                    PencilCreateNowButton(
                                      onPressed: () {
                                        final t = template;
                                        if (t == null) return;
                                        final need = _homeCostDisplay480p(t);
                                        if (need > 0 &&
                                            UserState.credits.value < need) {
                                          openPurchaseStore(context);
                                          return;
                                        }
                                        Navigator.of(context).push(
                                          MaterialPageRoute<void>(
                                            builder: (_) => GenerateScreen(
                                              template: t,
                                            ),
                                          ),
                                        );
                                      },
                                    ),
                                  ],
                                );
                              },
                            );
                          },
                        );
                      },
                    ),
                  ),
                ],
              ),
            ),
          ),
        ],
      ),
    );
  }
}

/// 全屏循环播放 [ExtConfigItem.videoUrl]（或 `image` 为视频 URL）；失败则回退为静态图。
///
/// [isActive] 为 false 时释放 [VideoPlayerController]，仅保留封面，避免 PageView 多路解码卡死。
class _HomeItemVideoBackground extends StatefulWidget {
  const _HomeItemVideoBackground({
    required this.item,
    this.isActive = true,
  });

  final ExtConfigItem item;

  /// 当前项是否在 [PageView] 可视页（与 [_pageController.page] 对齐）。
  final bool isActive;

  @override
  State<_HomeItemVideoBackground> createState() =>
      _HomeItemVideoBackgroundState();
}

class _HomeItemVideoBackgroundState extends State<_HomeItemVideoBackground> {
  VideoPlayerController? _controller;
  bool _failed = false;

  /// 含 ExoPlayer 错误（416、UnrecognizedInputFormat、坏缓存等）时的自动重试次数。
  static const int _maxOpenRetries = 6;
  int _openRetries = 0;

  /// 上一轮已判定磁盘缓存不可播：跳过后续 [getFileFromCache]，避免反复读坏文件卡住。
  bool _forceNetworkOnly = false;

  Timer? _retryTimer;
  bool _recovering = false;

  /// 封面解码完成监听（先封面后视频，避免长时间空白）。
  ImageStream? _coverImageStream;
  ImageStreamListener? _coverImageListener;

  String get _playUrl {
    final v = widget.item.videoUrl?.trim();
    if (v != null && v.isNotEmpty) return v;
    return widget.item.image.trim();
  }

  @override
  void initState() {
    super.initState();
    if (widget.isActive) {
      _preloadCoverThenStartVideo();
    }
  }

  @override
  void didUpdateWidget(_HomeItemVideoBackground oldWidget) {
    super.didUpdateWidget(oldWidget);
    if (oldWidget.isActive != widget.isActive) {
      if (!widget.isActive) {
        _retryTimer?.cancel();
        _retryTimer = null;
        _recovering = false;
        _openRetries = 0;
        _removeCoverListener();
        _disposePlayback();
        if (mounted) setState(() {});
        return;
      }
      _failed = false;
      _forceNetworkOnly = false;
      _preloadCoverThenStartVideo();
      return;
    }
    final oldUrl = _videoUrlForItem(oldWidget.item);
    final newUrl = _videoUrlForItem(widget.item);
    if (oldUrl != newUrl) {
      _openRetries = 0;
      _failed = false;
      _recovering = false;
      _forceNetworkOnly = false;
      _removeCoverListener();
      _disposePlayback();
      if (widget.isActive) {
        _preloadCoverThenStartVideo();
      }
    }
  }

  static String _videoUrlForItem(ExtConfigItem item) {
    final v = item.videoUrl?.trim();
    if (v != null && v.isNotEmpty) return v;
    return item.image.trim();
  }

  /// 与 [_HomeItemPageContent] 一致：主图 + 兜底图。
  static String _coverUrlForItem(ExtConfigItem item) {
    final u = item.image.trim();
    if (u.isNotEmpty) return u;
    return item.imageFix?.trim() ?? '';
  }

  void _removeCoverListener() {
    final stream = _coverImageStream;
    final listener = _coverImageListener;
    if (stream != null && listener != null) {
      stream.removeListener(listener);
    }
    _coverImageStream = null;
    _coverImageListener = null;
  }

  void _preloadCoverThenStartVideo() {
    if (!widget.isActive) return;
    _removeCoverListener();
    final coverUrl = _coverUrlForItem(widget.item);
    if (coverUrl.isEmpty) {
      unawaited(_startPlaybackAsync());
      return;
    }
    final u = Uri.tryParse(coverUrl);
    if (u == null || !(u.isScheme('http') || u.isScheme('https'))) {
      unawaited(_startPlaybackAsync());
      return;
    }
    final provider = CachedNetworkImageProvider(coverUrl);
    final stream = provider.resolve(const ImageConfiguration());
    _coverImageStream = stream;
    final listener = ImageStreamListener(
      (ImageInfo image, bool synchronousCall) {
        _removeCoverListener();
        unawaited(_startPlaybackAsync());
      },
      onError: (Object exception, StackTrace? stackTrace) {
        _removeCoverListener();
        unawaited(_startPlaybackAsync());
      },
    );
    _coverImageListener = listener;
    stream.addListener(listener);
  }

  /// 先 pause 再 dispose，避免 ExoPlayer 已释放后仍收到 [pause]/setPlayWhenReady（dead thread）。
  static Future<void> _pauseThenDispose(VideoPlayerController c) async {
    try {
      await c.pause();
    } catch (_) {}
    try {
      await c.dispose();
    } catch (_) {}
  }

  void _disposePlayback() {
    _retryTimer?.cancel();
    _retryTimer = null;
    final c = _controller;
    if (c != null) {
      c.removeListener(_onVideoValueChanged);
      _controller = null;
      unawaited(_pauseThenDispose(c));
    }
  }

  /// 磁盘已有有效缓存则 [VideoPlayerController.file]；否则网络流式播放。
  /// 仅在 [initialize] + [play] 成功后再 [downloadFile]，避免并行下载把 HTML/错包写入缓存导致 UnrecognizedInputFormat。
  Future<void> _startPlaybackAsync() async {
    if (!widget.isActive) return;
    final playUrl = _playUrl;
    final uri = Uri.tryParse(playUrl);
    if (uri == null || !(uri.isScheme('http') || uri.isScheme('https'))) {
      if (mounted) setState(() => _failed = true);
      return;
    }
    _disposePlayback();

    final cacheKey = videoCacheKeyForUrl(playUrl);
    VideoPlayerController? controller;
    try {
      if (!_forceNetworkOnly) {
        final cached = await funymeeVideoCacheManager.getFileFromCache(cacheKey);
        if (cached != null &&
            cached.validTill.isAfter(DateTime.now()) &&
            await cached.file.exists() &&
            await videoCachedFileLooksPlayable(cached.file)) {
          controller = VideoPlayerController.file(cached.file);
        } else if (cached != null && await cached.file.exists()) {
          await funymeeVideoCacheManager.removeFile(cacheKey);
        }
      }
      controller ??= VideoPlayerController.networkUrl(uri);
    } catch (_) {
      controller = VideoPlayerController.networkUrl(uri);
    }

    if (!mounted || playUrl != _playUrl || !widget.isActive) {
      unawaited(_pauseThenDispose(controller));
      return;
    }

    controller.addListener(_onVideoValueChanged);
    _controller = controller;

    try {
      await controller.initialize().timeout(
        const Duration(seconds: 20),
        onTimeout: () => throw TimeoutException('video init', const Duration(seconds: 20)),
      );
    } catch (_) {
      if (mounted) _scheduleRecoverFromError();
      return;
    }

    if (!mounted ||
        _controller != controller ||
        playUrl != _playUrl ||
        !widget.isActive) return;
    if (controller.value.hasError) {
      if (mounted) _scheduleRecoverFromError();
      return;
    }

    _openRetries = 0;
    controller.setLooping(true);
    try {
      await controller.play();
    } catch (_) {
      if (mounted) _scheduleRecoverFromError();
      return;
    }

    if (!mounted ||
        _controller != controller ||
        playUrl != _playUrl ||
        !widget.isActive) return;
    if (controller.value.hasError) {
      if (mounted) _scheduleRecoverFromError();
      return;
    }

    _forceNetworkOnly = false;
    unawaited(funymeeVideoCacheManager.downloadFile(playUrl, key: cacheKey));
    setState(() {});
  }

  void _onVideoValueChanged() {
    final c = _controller;
    if (c == null || !mounted || _recovering) return;
    if (!c.value.hasError) return;
    c.removeListener(_onVideoValueChanged);
    _scheduleRecoverFromError();
  }

  void _scheduleRecoverFromError() {
    if (!mounted || _failed || !widget.isActive) return;
    if (_recovering) return;
    if (_openRetries >= _maxOpenRetries) {
      setState(() => _failed = true);
      _disposePlayback();
      return;
    }
    _recovering = true;
    _openRetries += 1;
    final cacheKey = videoCacheKeyForUrl(_playUrl);
    unawaited(funymeeVideoCacheManager.removeFile(cacheKey));
    _forceNetworkOnly = true;
    _disposePlayback();
    setState(() {});

    _retryTimer?.cancel();
    _retryTimer = Timer(const Duration(milliseconds: 220), () {
      _retryTimer = null;
      if (!mounted) return;
      _recovering = false;
      unawaited(_startPlaybackAsync());
    });
  }

  @override
  void dispose() {
    _retryTimer?.cancel();
    _removeCoverListener();
    _disposePlayback();
    super.dispose();
  }

  Widget _coverPlaceholder() {
    return ColoredBox(
      color: Colors.white.withValues(alpha: 0.12),
      child: Center(
        child: SizedBox(
          width: 28,
          height: 28,
          child: CircularProgressIndicator(
            strokeWidth: 2,
            color: PencilTheme.homeTextPrimary.withValues(alpha: 0.7),
          ),
        ),
      ),
    );
  }

  Widget _buildCoverLayer() {
    final coverUrl = _coverUrlForItem(widget.item);
    if (coverUrl.isEmpty) return _coverPlaceholder();
    final u = Uri.tryParse(coverUrl);
    if (u == null || !(u.isScheme('http') || u.isScheme('https'))) {
      return _coverPlaceholder();
    }
    return CachedNetworkImage(
      imageUrl: coverUrl,
      fit: BoxFit.cover,
      width: double.infinity,
      height: double.infinity,
      placeholder: (_, _) => _coverPlaceholder(),
      errorWidget: (_, _, _) => _coverPlaceholder(),
      fadeInDuration: Duration.zero,
      fadeOutDuration: Duration.zero,
    );
  }

  @override
  Widget build(BuildContext context) {
    if (!widget.isActive) {
      return SizedBox.expand(
        child: Stack(
          fit: StackFit.expand,
          children: [
            Positioned.fill(child: _buildCoverLayer()),
          ],
        ),
      );
    }
    if (_failed) {
      return _HomeItemPageContent(item: widget.item, forceImage: true);
    }
    final c = _controller;
    return SizedBox.expand(
      child: LayoutBuilder(
        builder: (context, constraints) {
          final cw = constraints.maxWidth;
          final ch = constraints.maxHeight;
          if (c != null && c.value.isInitialized) {
            final w = c.value.size.width;
            final h = c.value.size.height;
            if (w > 0 &&
                h > 0 &&
                cw.isFinite &&
                ch.isFinite &&
                cw > 0 &&
                ch > 0) {
              // 视口固定为 cw×ch；FittedBox.cover 铺满裁切，避免 Transform.scale 只改绘制不改布局导致「画中画」。
              return Stack(
                fit: StackFit.expand,
                children: [
                  Positioned.fill(child: _buildCoverLayer()),
                  Positioned.fill(
                    child: ClipRect(
                      child: SizedBox(
                        width: cw,
                        height: ch,
                        child: FittedBox(
                          fit: BoxFit.cover,
                          alignment: Alignment.center,
                          clipBehavior: Clip.none,
                          child: SizedBox(
                            width: w,
                            height: h,
                            child: VideoPlayer(c),
                          ),
                        ),
                      ),
                    ),
                  ),
                ],
              );
            }
          }
          return Stack(
            fit: StackFit.expand,
            children: [
              Positioned.fill(child: _buildCoverLayer()),
            ],
          );
        },
      ),
    );
  }
}

/// 单个 extConfig item：全屏铺满（与底层背景同尺寸），无圆角。
class _HomeItemPageContent extends StatelessWidget {
  const _HomeItemPageContent({
    super.key,
    required this.item,
    this.forceImage = false,
    this.videoActive = true,
  });

  final ExtConfigItem item;

  /// 为 true 时跳过视频播放（用于视频解码失败回退为封面图）。
  final bool forceImage;

  /// 为 false 时不在 [PageView] 当前可视页，视频应释放解码器。
  final bool videoActive;

  @override
  Widget build(BuildContext context) {
    if (!forceImage && item.isVideoItem) {
      return _HomeItemVideoBackground(
        item: item,
        isActive: videoActive,
      );
    }
    final imageUrl = item.image.trim();
    final fixUrl = item.imageFix?.trim();

    if (imageUrl.isNotEmpty) {
      return SizedBox.expand(
        child: CachedNetworkImage(
          imageUrl: imageUrl,
          fit: BoxFit.cover,
          placeholder: (_, _) => Container(
            color: Colors.white.withValues(alpha: 0.12),
            alignment: Alignment.center,
            child: SizedBox(
              width: 28,
              height: 28,
              child: CircularProgressIndicator(
                strokeWidth: 2,
                color:
                    PencilTheme.homeTextPrimary.withValues(alpha: 0.7),
              ),
            ),
          ),
          errorWidget: (_, _, _) {
            if (fixUrl != null && fixUrl.isNotEmpty) {
              return CachedNetworkImage(
                imageUrl: fixUrl,
                fit: BoxFit.cover,
                errorWidget: (_, _, _) => _placeholder(),
              );
            }
            return _placeholder();
          },
        ),
      );
    }
    if (fixUrl != null && fixUrl.isNotEmpty) {
      return SizedBox.expand(
        child: CachedNetworkImage(
          imageUrl: fixUrl,
          fit: BoxFit.cover,
          errorWidget: (_, _, _) => _placeholder(),
        ),
      );
    }
    return _placeholder();
  }

  Widget _placeholder() {
    return SizedBox.expand(
      child: ColoredBox(
        color: Colors.white.withValues(alpha: 0.1),
        child: Center(
          child: Icon(
            Icons.image_outlined,
            size: 48,
            color: PencilTheme.homeTextPrimary.withValues(alpha: 0.45),
          ),
        ),
      ),
    );
  }
}