// Author: fruit.com.cn

import 'dart:async';

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

import '../../core/config/app_config.dart';
import '../../core/data/models/drama.dart';
import '../../core/data/services/home_feed_controller.dart';
import '../../core/data/services/catalog_controller.dart';
import '../../core/data/services/catalog_retry.dart';
import '../../core/data/services/category_controller.dart';
import '../../core/platform/haptics.dart';
import '../../core/theme/app_colors.dart';
import '../../core/theme/app_theme.dart';
import '../../core/widgets/app_bottom_nav.dart';
import '../../core/widgets/catalog_debug_info.dart';
import '../../core/widgets/catalog_endpoint_editor.dart';
import '../../core/widgets/empty_state.dart';
import '../../l10n/app_localizations.dart';
import '../discover/discover_types.dart';
import '../discover/discover_view.dart';
import '../create/create_view.dart';
import '../mine/mine_types.dart';
import '../player/widgets/home_feed_header.dart';
import '../player/player_view.dart';
import '../mine/mine_view.dart';
import 'home_feed_channel.dart';
import 'home_binding.dart';
import 'home_logic.dart';

class HomePage extends StatefulWidget {
  const HomePage({super.key});

  @override
  State<HomePage> createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> with WidgetsBindingObserver {
  static const _androidSplashAsset = 'assets/icon/splash_logo_android12.png';
  static const _defaultSplashAsset = 'assets/icon/splash_logo.png';
  static const _androidSplashSize = 288.0;
  static const _defaultSplashSize = 384.0;

  bool _resumeRetryInFlight = false;
  HomeFeedController? _homeFeed;
  bool _recommendSeeded = false;

  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addObserver(this);
  }

  @override
  void dispose() {
    _homeFeed?.dispose();
    WidgetsBinding.instance.removeObserver(this);
    super.dispose();
  }

  @override
  void didChangeAppLifecycleState(AppLifecycleState state) {
    if (state != AppLifecycleState.resumed || _resumeRetryInFlight) return;
    final catalog = context.read<CatalogController>();
    final categories = context.read<CategoryController>();
    if (catalog.error == null && categories.error == null) return;
    unawaited(_retryAfterResume(catalog, categories));
  }

  Future<void> _retryAfterResume(
    CatalogController catalog,
    CategoryController categories,
  ) async {
    _resumeRetryInFlight = true;
    try {
      await AppConfig.probeAndApplyBaseUrl();
      await Future.wait([
        if (catalog.error != null) catalog.load(),
        if (categories.error != null) categories.load(),
      ]);
    } finally {
      _resumeRetryInFlight = false;
    }
  }

  Future<void> _retryHome(CatalogController catalog) {
    return retryCatalogLoad(reload: catalog.load);
  }

  Future<void> _editHomeEndpoint(CatalogController catalog) {
    return showCatalogEndpointEditor(context, reload: catalog.load);
  }

  @override
  Widget build(BuildContext context) {
    final catalog = context.watch<CatalogController>();
    final l10n = AppLocalizations.of(context)!;
    return Theme(
      data: AppTheme.light(),
      child: _buildHome(context, catalog, l10n),
    );
  }

  Widget _buildHome(
    BuildContext context,
    CatalogController catalog,
    AppLocalizations l10n,
  ) {
    if (catalog.loading) {
      return catalog.settled ? _retryLoading() : _startupSplash();
    }
    if (catalog.error != null) {
      return Scaffold(
        backgroundColor: Colors.transparent,
        body: HomeFailureView(
          error: catalog.debugError ?? catalog.error,
          onRetry: () => unawaited(_retryHome(catalog)),
          onEditEndpoint: () => unawaited(_editHomeEndpoint(catalog)),
        ),
      );
    }
    if (catalog.dramas.isEmpty) {
      return Scaffold(
        backgroundColor: Colors.transparent,
        body: EmptyState(
          key: const Key('home-empty'),
          icon: Icons.movie_outlined,
          title: l10n.noStories,
          subtitle: l10n.emptyHint,
          actionLabel: l10n.retry,
          onAction: catalog.load,
        ),
      );
    }

    final homeFeed = _ensureHomeFeed(catalog);
    if (!_recommendSeeded) {
      _recommendSeeded = true;
      homeFeed.seedRecommend(catalog.dramas);
      WidgetsBinding.instance.addPostFrameCallback((_) {
        if (mounted) unawaited(_refreshRecommendAndPrefetch(homeFeed));
      });
    }
    return _HomeTabs(key: const Key('home-tabs'), feedController: homeFeed);
  }

  HomeFeedController _ensureHomeFeed(CatalogController catalog) {
    return _homeFeed ??= HomeFeedController(catalog.repository);
  }

  Future<void> _refreshRecommendAndPrefetch(HomeFeedController homeFeed) async {
    if (await homeFeed.refreshCurrent()) {
      await homeFeed.prefetchChannels();
    }
  }

  Widget _startupSplash() {
    final isAndroid = defaultTargetPlatform == TargetPlatform.android;
    final size = isAndroid ? _androidSplashSize : _defaultSplashSize;
    return AnnotatedRegion<SystemUiOverlayStyle>(
      value: SystemUiOverlayStyle.light,
      child: ColoredBox(
        color: AppColors.splashInk,
        child: Center(
          child: Image.asset(
            isAndroid ? _androidSplashAsset : _defaultSplashAsset,
            key: const Key('startup-splash'),
            width: size,
            height: size,
            fit: BoxFit.contain,
          ),
        ),
      ),
    );
  }

  Widget _retryLoading() {
    return AnnotatedRegion<SystemUiOverlayStyle>(
      value: SystemUiOverlayStyle.light,
      child: const Scaffold(
        backgroundColor: AppColors.splashInk,
        body: Center(child: CircularProgressIndicator(color: AppColors.blue)),
      ),
    );
  }
}

/// 首页目录加载失败与重试入口。
class HomeFailureView extends StatelessWidget {
  const HomeFailureView({
    super.key,
    this.error,
    required this.onRetry,
    this.onEditEndpoint,
  });

  final String? error;
  final VoidCallback onRetry;
  final VoidCallback? onEditEndpoint;

  @override
  Widget build(BuildContext context) {
    final l10n = AppLocalizations.of(context)!;
    return EmptyState(
      icon: Icons.cloud_off_rounded,
      title: l10n.catalogError,
      actionLabel: l10n.retry,
      onAction: onRetry,
      footer: kDebugMode
          ? CatalogDebugInfo(error: error, onEditEndpoint: onEditEndpoint)
          : null,
    );
  }
}

/// 四个根页面共享同一路由并保持各自状态。
class _HomeTabs extends StatefulWidget {
  const _HomeTabs({super.key, required this.feedController});

  final HomeFeedController feedController;

  @override
  State<_HomeTabs> createState() => _HomeTabsState();
}

class _HomeTabsState extends State<_HomeTabs> {
  late final HomeLogic logic;
  List<Drama>? _visibleDramas;
  HomeFeedChannel? _visibleChannel;

  @override
  void initState() {
    super.initState();
    logic = HomeBinding().create(widget.feedController.dramas);
    _visibleDramas = widget.feedController.dramas;
    _visibleChannel = widget.feedController.channel;
    widget.feedController.addListener(_onFeedChanged);
  }

  @override
  void dispose() {
    widget.feedController.removeListener(_onFeedChanged);
    logic.dispose();
    super.dispose();
  }

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

  @override
  Widget build(BuildContext context) {
    return ListenableBuilder(
      listenable: logic,
      builder: (context, _) => _scaffold(context),
    );
  }

  Widget _scaffold(BuildContext context) {
    final l10n = AppLocalizations.of(context)!;
    final feed = logic.tab == 0;
    final content = PopScope(
      canPop: false,
      onPopInvokedWithResult: (didPop, _) {
        if (didPop) return;
        logic.onSystemBack();
      },
      child: Scaffold(
        key: logic.scaffoldKey,
        backgroundColor: Colors.transparent,
        resizeToAvoidBottomInset: false,
        body: _body(context),
        bottomNavigationBar: logic.videoImmersive ? null : _nav(context, l10n),
      ),
    );
    return AnnotatedRegion<SystemUiOverlayStyle>(
      value: feed ? SystemUiOverlayStyle.light : SystemUiOverlayStyle.dark,
      child: feed
          ? content
          : DecoratedBox(
              key: const Key('home-page-gradient'),
              decoration: const BoxDecoration(gradient: AppTheme.pageGradient),
              child: content,
            ),
    );
  }

  Widget _body(BuildContext context) {
    return IndexedStack(
      index: logic.tab,
      children: [
        _home(context),
        _discover(context),
        const CreatePage(),
        _my(context),
      ],
    );
  }

  Widget _home(BuildContext context) {
    final currentDramas = widget.feedController.dramas;
    final currentChannel = widget.feedController.channel;
    if (currentDramas.isNotEmpty) {
      _visibleDramas = currentDramas;
      _visibleChannel = currentChannel;
    }
    if (currentDramas.isEmpty && !widget.feedController.loadingFirstPage) {
      return _feedChannelPlaceholder(context);
    }
    final visibleDramas = _visibleDramas;
    final visibleChannel = _visibleChannel;
    final switching =
        currentDramas.isEmpty && widget.feedController.loadingFirstPage;
    if (visibleDramas == null ||
        visibleDramas.isEmpty ||
        visibleChannel == null) {
      return _feedChannelPlaceholder(context);
    }
    final playerDramas = currentDramas.isEmpty ? visibleDramas : currentDramas;
    final playerChannel = currentDramas.isEmpty
        ? visibleChannel
        : currentChannel;
    return Stack(
      fit: StackFit.expand,
      children: [
        PlayerPage(
          homeMode: true,
          embedded: true,
          active: logic.tab == 0,
          drama: playerDramas.first,
          initialIndex: 0,
          feedDramas: playerDramas,
          feedChannel: playerChannel,
          headerChannel: currentChannel,
          onOpenFullPlayer: (drama, episode) =>
              logic.playDrama(context, drama, episodeId: episode.id),
          onRefreshFeed: widget.feedController.refreshCurrent,
          onLoadMore: widget.feedController.loadMore,
          onChannelSelected: _selectFeedChannel,
          onDramaChanged: logic.onDramaChanged,
          onImmersiveChanged: logic.onImmersiveChanged,
          onSearch: () => logic.select(1, search: true),
          onDiscover: () => logic.select(1),
          onMy: () => logic.select(3),
        ),
        if (switching)
          Positioned.fill(
            child: IgnorePointer(
              key: const Key('home-feed-channel-loading'),
              child: ColoredBox(
                color: Colors.black26,
                child: Center(
                  child: SizedBox.square(
                    dimension: 24,
                    child: CircularProgressIndicator(
                      strokeWidth: 2.4,
                      color: Colors.white70,
                    ),
                  ),
                ),
              ),
            ),
          ),
      ],
    );
  }

  Widget _feedChannelPlaceholder(BuildContext context) {
    final l10n = AppLocalizations.of(context)!;
    return Stack(
      fit: StackFit.expand,
      children: [
        const ColoredBox(color: Colors.black),
        SafeArea(
          bottom: false,
          child: Column(
            children: [
              HomeFeedHeader(
                l10n: l10n,
                channel: widget.feedController.channel,
                onChannelSelected: _selectFeedChannel,
                onRefresh: () => _refreshPlaceholder(context),
                onSearch: () => logic.select(1, search: true),
                onMore: () {},
              ),
              Expanded(
                child: widget.feedController.loadingFirstPage
                    ? const Center(
                        child: SizedBox.square(
                          dimension: 24,
                          child: CircularProgressIndicator(
                            key: Key('home-feed-channel-loading'),
                            strokeWidth: 2.4,
                            color: Colors.white70,
                          ),
                        ),
                      )
                    : EmptyState(
                        icon: Icons.movie_outlined,
                        title: l10n.noStories,
                        actionLabel: l10n.retry,
                        onAction: () =>
                            unawaited(widget.feedController.refreshCurrent()),
                      ),
              ),
            ],
          ),
        ),
      ],
    );
  }

  Future<bool> _refreshPlaceholder(BuildContext context) async {
    final ok = await widget.feedController.refreshCurrent();
    if (!ok && context.mounted) {
      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(content: Text(AppLocalizations.of(context)!.catalogError)),
      );
    }
    return ok;
  }

  void _selectFeedChannel(HomeFeedChannel channel) {
    unawaited(widget.feedController.selectChannel(channel));
  }

  Widget _discover(BuildContext context) {
    return DiscoverPage(
      active: logic.tab == 1,
      searchRequest: logic.searchRequest,
      callbacks: DiscoverPageCallbacks(
        onAction: logic.discoverAction,
        onDramaSelected: (drama) => logic.playDrama(context, drama),
        onProfile: logic.openProfile,
      ),
    );
  }

  Widget _my(BuildContext context) {
    return MyPage(
      active: logic.tab == 3,
      callbacks: MyPageCallbacks(
        onAction: logic.myAction,
        onDramaSelected: (drama) => logic.openDrama(context, drama),
      ),
    );
  }

  Widget _nav(BuildContext context, AppLocalizations l10n) {
    return AppBottomNav(
      barKey: const Key('home-tabs-bar'),
      dark: logic.tab == 0,
      items: [
        _navItem(context, l10n, 0),
        _navItem(context, l10n, 1),
        _navItem(context, l10n, 2),
        _navItem(context, l10n, 3),
      ],
    );
  }

  AppBottomNavItem _navItem(
    BuildContext context,
    AppLocalizations l10n,
    int index,
  ) {
    final selected = logic.tab == index;
    return switch (index) {
      0 => AppBottomNavItem(
        tabKey: const Key('tab-home'),
        icon: Icons.home_outlined,
        selectedIcon: Icons.home_rounded,
        label: l10n.homeTab,
        selected: selected,
        onTap: () => _selectTab(context, index),
      ),
      1 => AppBottomNavItem(
        tabKey: const Key('tab-theater'),
        icon: Icons.explore_outlined,
        selectedIcon: Icons.explore_rounded,
        label: l10n.theaterTab,
        selected: selected,
        onTap: () => _selectTab(context, index),
      ),
      2 => AppBottomNavItem(
        tabKey: const Key('tab-create'),
        icon: Icons.add_box_outlined,
        selectedIcon: Icons.add_box_rounded,
        label: l10n.createTab,
        selected: selected,
        onTap: () => _selectTab(context, index),
      ),
      _ => AppBottomNavItem(
        tabKey: const Key('tab-mine'),
        icon: Icons.person_outline_rounded,
        selectedIcon: Icons.person_rounded,
        label: l10n.myTab,
        selected: selected,
        onTap: () => _selectTab(context, index),
      ),
    };
  }

  void _selectTab(BuildContext context, int tab) {
    final same = logic.tab == tab;
    if (!same) {
      unawaited(context.read<Haptics>().selectionClick());
    }
    logic.select(tab);
  }
}