// Author: fruit.com.cn

import 'dart:async';

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

import '../../core/config/app_config.dart';
import '../../core/data/remote/catalog_api.dart';
import '../../core/data/services/home_feed_controller.dart';
import '../../core/data/services/catalog_controller.dart';
import '../../core/data/services/category_controller.dart';
import '../../core/data/services/favorite_controller.dart';
import '../../core/data/services/wallet_controller.dart';
import '../../core/platform/haptics.dart';
import '../../core/theme/app_colors.dart';
import '../../core/theme/app_theme.dart';
import '../../core/widgets/auth_gate.dart';
import '../../core/widgets/app_root_tab.dart';
import '../discover/search_page.dart';
import '../following/following_page.dart';
import '../filter/filter_page.dart';
import '../mine/mine_types.dart';
import '../recommend/recommend_page.dart';
import '../mine/mine_view.dart';
import '../store/vip_page.dart';
import '../wallet/wallet_page.dart';
import 'home_binding.dart';
import 'home_logic.dart';
import 'widgets/home_feed_grid.dart';
import 'widgets/home_grid_header.dart';

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

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

class _HomePageState extends State<HomePage> with WidgetsBindingObserver {
  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;
    }
  }

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

  Widget _buildHome(BuildContext context, CatalogController catalog) {
    final homeFeed = _ensureHomeFeed(catalog);
    if (!_recommendSeeded && catalog.dramas.isNotEmpty) {
      _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();
    }
  }
}

/// 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;

  @override
  void initState() {
    super.initState();
    logic = HomeBinding().create(widget.feedController.dramas);
  }

  @override
  void dispose() {
    logic.dispose();
    super.dispose();
  }

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

  Widget _scaffold(BuildContext context) {
    final mediaTab = logic.tab == 0 || logic.tab == 1;
    final content = PopScope(
      canPop: false,
      onPopInvokedWithResult: (didPop, _) {
        if (didPop) return;
        logic.onSystemBack();
      },
      child: Scaffold(
        key: logic.scaffoldKey,
        backgroundColor: AppColors.transparent,
        resizeToAvoidBottomInset: false,
        body: _body(context),
        bottomNavigationBar: logic.videoImmersive ? null : _nav(context),
      ),
    );
    return AnnotatedRegion<SystemUiOverlayStyle>(
      value: SystemUiOverlayStyle.light,
      child: mediaTab
          ? content
          : DecoratedBox(
              key: const Key('home-page-gradient'),
              decoration: const BoxDecoration(gradient: AppTheme.pageGradient),
              child: content,
            ),
    );
  }

  Widget _body(BuildContext context) {
    final pages = <Widget>[
      _homeGrid(context),
      _recommend(context),
      FollowingPage(
        onGoHome: () => logic.select(0),
        favoriteController: context.read<FavoriteController>(),
        historyRequest: logic.followingHistoryRequest,
      ),
      _my(context),
    ];
    return IndexedStack(
      index: logic.tab,
      children: [
        for (var index = 0; index < pages.length; index++)
          TickerMode(enabled: logic.tab == index, child: pages[index]),
      ],
    );
  }

  Widget _homeGrid(BuildContext context) {
    return HomeFeedGrid(
      feedController: widget.feedController,
      callbacks: HomeGridCallbacks(
        onSearch: () => _openSearch(context),
        onOpenVip: () => unawaited(_openVip(context)),
        onOpenWallet: () => unawaited(_openWallet(context)),
        onOpenFilter: () => _pushPage(context, const FilterPage()),
      ),
      onOpenDrama: (drama) => unawaited(logic.playDrama(context, drama)),
    );
  }

  Widget _recommend(BuildContext context) {
    return RecommendPage(
      feedController: widget.feedController,
      catalogApi: _catalogApi(context),
      active: logic.tab == 1,
      videoOnly: logic.videoImmersive,
      onImmersiveChanged: logic.onImmersiveChanged,
      onSearch: () => _openSearch(context),
    );
  }

  CatalogApi? _catalogApi(BuildContext context) {
    try {
      return context.read<CatalogApi>();
    } on ProviderNotFoundException {
      return null;
    }
  }

  void _openSearch(BuildContext context) {
    Navigator.of(
      context,
    ).push<void>(MaterialPageRoute(builder: (_) => const SearchPage()));
  }

  void _pushPage(BuildContext context, Widget page) {
    Navigator.of(context).push<void>(MaterialPageRoute(builder: (_) => page));
  }

  Future<void> _openVip(BuildContext context) async {
    if (!await ensureSignedIn(context) || !context.mounted) return;
    final wallet = context.read<WalletController>();
    await Navigator.of(context).push<void>(
      MaterialPageRoute(
        builder: (_) => VipPage(onPurchased: () => unawaited(wallet.load())),
      ),
    );
  }

  Future<void> _openWallet(BuildContext context) async {
    if (!await ensureSignedIn(context) || !context.mounted) return;
    await Navigator.of(
      context,
    ).push<void>(MaterialPageRoute(builder: (_) => const WalletPage()));
  }

  Widget _my(BuildContext context) {
    return MyPage(
      active: logic.tab == 3,
      callbacks: MyPageCallbacks(
        onAction: logic.myAction,
        onOpenHistoryTab: logic.openFollowingHistory,
      ),
    );
  }

  Widget _nav(BuildContext context) {
    return AppRootBottomNav(
      barKey: const Key('home-tabs-bar'),
      selected: AppRootTab.values[logic.tab],
      onSelected: (tab) => _selectTab(context, tab.index),
    );
  }

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