import 'dart:async';

import 'package:file_selector/file_selector.dart';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:webview_flutter/webview_flutter.dart';
import 'package:webview_flutter_android/webview_flutter_android.dart';

import 'config.dart';

Future<void> main() async {
  WidgetsFlutterBinding.ensureInitialized();
  // 全面屏：内容延伸到状态栏/导航栏之下，刘海与手势区交给 SafeArea 处理
  await SystemChrome.setEnabledSystemUIMode(SystemUiMode.edgeToEdge);
  runApp(const DshApp());
}

class DshApp extends StatelessWidget {
  const DshApp({super.key});

  @override
  Widget build(BuildContext context) {
    return AnnotatedRegion<SystemUiOverlayStyle>(
      // 站点为深色主题：状态栏透明、图标反白
      value: const SystemUiOverlayStyle(
        statusBarColor: Colors.transparent,
        statusBarIconBrightness: Brightness.light,
        systemNavigationBarColor: Colors.transparent,
        systemNavigationBarIconBrightness: Brightness.light,
      ),
      child: MaterialApp(
        title: 'DSH 工作台',
        debugShowCheckedModeBanner: false,
        theme: ThemeData(
          useMaterial3: true,
          colorScheme: ColorScheme.fromSeed(
            seedColor: const Color(kThemeColorValue),
            brightness: Brightness.dark,
          ),
          scaffoldBackgroundColor: const Color(kThemeColorValue),
        ),
        home: const HomePage(),
      ),
    );
  }
}

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

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

class _HomePageState extends State<HomePage> {
  /// 原生下载通道（MainActivity 中用系统 DownloadManager 实现）
  static const MethodChannel _downloadsChannel = MethodChannel(
    'dsh.workbench/downloads',
  );

  static final Uri _siteUri = Uri.parse(kSiteUrl);

  late final WebViewController _controller;
  bool _loading = true;
  String? _loadError;

  @override
  void initState() {
    super.initState();
    _controller = _buildController();
  }

  WebViewController _buildController() {
    final controller = WebViewController()
      ..setJavaScriptMode(JavaScriptMode.unrestricted)
      ..setBackgroundColor(const Color(kThemeColorValue))
      ..setNavigationDelegate(
        NavigationDelegate(
          onPageStarted: (_) {
            if (mounted) {
              setState(() {
                _loading = true;
                _loadError = null;
              });
            }
          },
          onPageFinished: (_) {
            if (mounted) setState(() => _loading = false);
          },
          onWebResourceError: (error) {
            // 只把主文档加载失败视作页面错误；子资源错误（图片等）
            // 以及被新导航打断（ERR_ABORTED）的情况交给页面自行处理
            if (!(error.isForMainFrame ?? false)) return;
            if (error.description.contains('ERR_ABORTED')) return;
            if (mounted) {
              setState(() {
                _loading = false;
                _loadError = error.description;
              });
            }
          },
          onNavigationRequest: _onNavigationRequest,
        ),
      )
      ..loadRequest(Uri.parse(kSiteUrl));

    // Android 专属能力：文件选择器（上传）、原生 JS 对话框（alert/confirm）
    final platform = controller.platform;
    if (platform is AndroidWebViewController) {
      platform
        ..setOnShowFileSelector(_onShowFileSelector)
        ..setOnJavaScriptAlertDialog(_onJavaScriptAlert)
        ..setOnJavaScriptConfirmDialog(_onJavaScriptConfirm);
    }
    return controller;
  }

  /// 面板用 window.location.assign 触发下载（文件/目录 ZIP/备份包），
  /// 这里拦下来交给原生 DownloadManager（携带登录 Cookie），WebView 停留原页。
  NavigationDecision _onNavigationRequest(NavigationRequest request) {
    final uri = Uri.tryParse(request.url);
    if (uri != null && _isPanelDownload(uri)) {
      _startDownload(uri);
      return NavigationDecision.prevent;
    }
    return NavigationDecision.navigate;
  }

  bool _isPanelDownload(Uri uri) {
    if (uri.host != _siteUri.host) return false;
    // 工作区文件/目录 ZIP 下载
    if (uri.path.endsWith('/api/ws/download')) return true;
    // 配置备份包下载
    if (uri.path.endsWith('/backups') &&
        uri.queryParameters.containsKey('download')) {
      return true;
    }
    return false;
  }

  Future<void> _startDownload(Uri uri) async {
    try {
      await _downloadsChannel.invokeMethod<bool>('download', {
        'url': uri.toString(),
      });
    } on PlatformException catch (e) {
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(content: Text('下载失败：${e.message ?? '未知错误'}')),
        );
      }
    }
  }

  /// WebView 里的 <input type="file"> 上传（工作区上传/备份导入）。
  /// Android 的类型过滤一次只支持单一 MIME 或单一扩展名，
  /// 多约束时退化为不限类型，避免选择器异常。
  Future<List<String>> _onShowFileSelector(FileSelectorParams params) async {
    final typeGroups = <XTypeGroup>[];
    final mimes = params.acceptTypes.where((t) => t.contains('/')).toList();
    if (mimes.length == 1) {
      typeGroups.add(XTypeGroup(mimeTypes: mimes));
    } else {
      final exts = params.acceptTypes
          .where((t) => t.startsWith('.'))
          .map((t) => t.toLowerCase())
          .toList();
      if (exts.length == 1) typeGroups.add(XTypeGroup(extensions: exts));
    }

    if (params.mode == FileSelectorMode.openMultiple) {
      final files = await openFiles(acceptedTypeGroups: typeGroups);
      return files.map((f) => f.path).toList();
    }
    final file = await openFile(acceptedTypeGroups: typeGroups);
    return file == null ? const <String>[] : [file.path];
  }

  /// 面板少量路径仍使用 window.alert / window.confirm，
  /// 未注册回调时 WebView 会静默返回 false，必须在这里补上。
  Future<void> _onJavaScriptAlert(JavaScriptAlertDialogRequest request) async {
    if (!mounted) return;
    await showDialog<void>(
      context: context,
      builder: (context) => AlertDialog(
        content: Text(request.message),
        actions: [
          TextButton(
            onPressed: () => Navigator.of(context).pop(),
            child: const Text('确定'),
          ),
        ],
      ),
    );
  }

  Future<bool> _onJavaScriptConfirm(
    JavaScriptConfirmDialogRequest request,
  ) async {
    if (!mounted) return false;
    final confirmed = await showDialog<bool>(
      context: context,
      builder: (context) => AlertDialog(
        content: Text(request.message),
        actions: [
          TextButton(
            onPressed: () => Navigator.of(context).pop(false),
            child: const Text('取消'),
          ),
          FilledButton(
            onPressed: () => Navigator.of(context).pop(true),
            child: const Text('确定'),
          ),
        ],
      ),
    );
    return confirmed ?? false;
  }

  Future<void> _onPopInvoked(bool didPop, Object? result) async {
    if (didPop) return;
    // 先回退 WebView 历史（SPA 内部导航），没有历史再退出应用
    if (await _controller.canGoBack()) {
      await _controller.goBack();
    } else {
      await SystemNavigator.pop();
    }
  }

  void _retry() {
    setState(() {
      _loadError = null;
      _loading = true;
    });
    unawaited(_controller.reload());
  }

  @override
  Widget build(BuildContext context) {
    return PopScope(
      canPop: false,
      onPopInvokedWithResult: _onPopInvoked,
      child: Scaffold(
        backgroundColor: const Color(kThemeColorValue),
        body: SafeArea(
          child: Stack(
            children: [
              WebViewWidget(controller: _controller),
              if (_loadError != null)
                _ErrorView(message: _loadError!, onRetry: _retry)
              else if (_loading)
                const _LoadingView(),
            ],
          ),
        ),
      ),
    );
  }
}

class _LoadingView extends StatelessWidget {
  const _LoadingView();

  @override
  Widget build(BuildContext context) {
    return const ColoredBox(
      color: Color(kThemeColorValue),
      child: Center(
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            CircularProgressIndicator(color: Colors.white70),
            SizedBox(height: 16),
            Text('正在加载…', style: TextStyle(color: Colors.white70)),
          ],
        ),
      ),
    );
  }
}

class _ErrorView extends StatelessWidget {
  const _ErrorView({required this.message, required this.onRetry});

  final String message;
  final VoidCallback onRetry;

  @override
  Widget build(BuildContext context) {
    return ColoredBox(
      color: const Color(kThemeColorValue),
      child: Center(
        child: Padding(
          padding: const EdgeInsets.all(32),
          child: Column(
            mainAxisSize: MainAxisSize.min,
            children: [
              const Icon(Icons.cloud_off, size: 56, color: Colors.white54),
              const SizedBox(height: 16),
              const Text(
                '无法连接到服务器',
                style: TextStyle(color: Colors.white, fontSize: 16),
              ),
              const SizedBox(height: 8),
              Text(
                message,
                textAlign: TextAlign.center,
                maxLines: 3,
                overflow: TextOverflow.ellipsis,
                style: const TextStyle(color: Colors.white38, fontSize: 12),
              ),
              const SizedBox(height: 20),
              FilledButton.icon(
                onPressed: onRetry,
                icon: const Icon(Icons.refresh),
                label: const Text('重试'),
              ),
            ],
          ),
        ),
      ),
    );
  }
}