import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:pad_scanner/services/app_config_service.dart';
import 'package:pad_scanner/pages/settings_page.dart';
import 'package:pad_scanner/pages/registration_page.dart';
import 'package:pad_scanner/pages/boxing_page.dart';
import 'package:pad_scanner/services/api_service.dart';

/// Module type enum for each available feature card
enum ModuleType { registration, boxing, shelfQuery }

/// Module status for PRD state tracking
enum ModuleStatus { online, developing, planning }

/// Function card data model per PRD §3.3
class FeatureCard {
  final ModuleType type;
  final String shortcut;
  final IconData icon;
  final String title;
  final ModuleStatus status;
  final String route;

  const FeatureCard({
    required this.type,
    required this.shortcut,
    required this.icon,
    required this.title,
    required this.status,
    required this.route,
  });
}

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

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

class _HomePageState extends State<HomePage> {
  final _apiService = ApiService();
  final _focusNode = FocusNode();
  bool _isCheckingConnection = false;
  bool _isConnected = false;
  String _apiAddress = '';

  /// Module registry from PRD §3.4
  static const _modules = [
    FeatureCard(
      type: ModuleType.registration,
      shortcut: '1',
      icon: Icons.local_shipping_outlined,
      title: '上架登记',
      status: ModuleStatus.online,
      route: '/registration',
    ),
    FeatureCard(
      type: ModuleType.boxing,
      shortcut: '2',
      icon: Icons.view_list_outlined,
      title: '装箱编号',
      status: ModuleStatus.online,
      route: '/boxing',
    ),
    FeatureCard(
      type: ModuleType.shelfQuery,
      shortcut: '3',
      icon: Icons.search_outlined,
      title: '货架查询',
      status: ModuleStatus.planning,
      route: '',
    ),
  ];

  @override
  void initState() {
    super.initState();
    _checkConnection();
    WidgetsBinding.instance.addPostFrameCallback((_) => _requestFocus());
  }

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

  void _requestFocus() {
    if (mounted) {
      _focusNode.requestFocus();
    }
  }

  void _onKeyEvent(KeyEvent event) {
    if (event is! KeyDownEvent) return;
    final module = _moduleFromShortcut(event);
    if (module == null) return;
    _onCardTap(module);
  }

  FeatureCard? _moduleFromShortcut(KeyEvent event) {
    final shortcut = _shortcutNumberFromKeyEvent(event);
    if (shortcut == 1) {
      return _modules[0];
    }
    if (shortcut == 2) {
      return _modules[1];
    }
    if (shortcut == 3) {
      return _modules[2];
    }
    return null;
  }

  int? _shortcutNumberFromKeyEvent(KeyEvent event) {
    final key = event.logicalKey;
    if (key == LogicalKeyboardKey.digit1 ||
        key == LogicalKeyboardKey.numpad1 ||
        event.character == '1') {
      return 1;
    }
    if (key == LogicalKeyboardKey.digit2 ||
        key == LogicalKeyboardKey.numpad2 ||
        event.character == '2') {
      return 2;
    }
    if (key == LogicalKeyboardKey.digit3 ||
        key == LogicalKeyboardKey.numpad3 ||
        event.character == '3') {
      return 3;
    }
    return null;
  }

  Future<void> _checkConnection() async {
    final configService = AppConfigService();
    final url = await configService.getString('api_url') ?? '';
    if (url.isEmpty) {
      setState(() {
        _isConnected = false;
        _apiAddress = '';
        _isCheckingConnection = false;
      });
      return;
    }

    setState(() => _isCheckingConnection = true);
    final ok = await _apiService.testConnection(url);
    if (!mounted) return;
    setState(() {
      _isConnected = ok;
      _apiAddress = url;
      _isCheckingConnection = false;
    });
  }

  void _onCardTap(FeatureCard card) {
    switch (card.status) {
      case ModuleStatus.online:
        _navigateToModule(card.type);
      case ModuleStatus.developing:
        _showToast('该功能正在开发中');
      case ModuleStatus.planning:
        _showToast('该功能规划中');
    }
  }

  void _showToast(String message) {
    ScaffoldMessenger.of(context).showSnackBar(
      SnackBar(content: Text(message), duration: const Duration(seconds: 2)),
    );
  }

  void _navigateToModule(ModuleType type) {
    late Widget targetPage;
    switch (type) {
      case ModuleType.registration:
        targetPage = const RegistrationPage();
        break;
      case ModuleType.boxing:
        targetPage = const BoxingPage();
        break;
      case ModuleType.shelfQuery:
        return; // 规划中，不导航
    }
    Navigator.push(context, MaterialPageRoute(builder: (_) => targetPage)).then(
      (_) {
        _checkConnection();
        _requestFocus();
      },
    );
  }

  void _navigateToSettings() {
    Navigator.push(
      context,
      MaterialPageRoute(builder: (_) => const SettingsPage()),
    ).then((_) {
      _checkConnection();
      _requestFocus();
    });
  }

  Color _getConnectionStatusColor() {
    if (_isCheckingConnection) return Colors.orange;
    return _isConnected ? Colors.green : Colors.red;
  }

  String _getConnectionStatusText() {
    if (_isCheckingConnection) return '● 正在检测连接...';
    if (!_isConnected || _apiAddress.isEmpty) return '● 未连接，请检查设置';
    return '● 已连接 $_apiAddress';
  }

  @override
  Widget build(BuildContext context) {
    final colorScheme = Theme.of(context).colorScheme;

    return KeyboardListener(
      focusNode: _focusNode,
      onKeyEvent: _onKeyEvent,
      child: Scaffold(
        appBar: AppBar(
          title: const SizedBox.shrink(),
          toolbarHeight: 44,
          actions: [
            Padding(
              padding: const EdgeInsets.only(right: 8),
              child: IconButton(
                icon: const Icon(Icons.settings),
                onPressed: _navigateToSettings,
              ),
            ),
          ],
        ),
        body: Column(
          children: [
            // Function cards area
            Expanded(
              child: ListView.builder(
                padding: const EdgeInsets.fromLTRB(16, 14, 16, 4),
                itemCount: _modules.length,
                itemBuilder: (context, index) {
                  final card = _modules[index];
                  return _buildFeatureCard(context, card);
                },
              ),
            ),

            // Bottom connection status bar
            Container(
              width: double.infinity,
              padding: const EdgeInsets.symmetric(vertical: 10, horizontal: 16),
              color: colorScheme.surfaceContainerHighest,
              child: Row(
                children: [
                  Container(
                    width: 8,
                    height: 8,
                    decoration: BoxDecoration(
                      color: _getConnectionStatusColor(),
                      shape: BoxShape.circle,
                    ),
                  ),
                  const SizedBox(width: 8),
                  Expanded(
                    child: Text(
                      _getConnectionStatusText(),
                      style: const TextStyle(fontSize: 13),
                      overflow: TextOverflow.ellipsis,
                    ),
                  ),
                ],
              ),
            ),
          ],
        ),
      ),
    );
  }

  Widget _buildFeatureCard(BuildContext context, FeatureCard card) {
    final canNavigate = card.status == ModuleStatus.online;

    return Padding(
      padding: const EdgeInsets.only(bottom: 16),
      child: InkWell(
        onTap: () => _onCardTap(card),
        borderRadius: BorderRadius.circular(8),
        child: Container(
          padding: const EdgeInsets.all(14),
          decoration: BoxDecoration(
            color: canNavigate ? Colors.white : Colors.grey.shade200,
            borderRadius: BorderRadius.circular(8),
            boxShadow: [
              BoxShadow(
                color: Colors.black.withValues(alpha: 0.05),
                blurRadius: 4,
                offset: const Offset(0, 2),
              ),
            ],
          ),
          child: Row(
            children: [
              Icon(
                card.icon,
                size: 22,
                color: canNavigate ? Colors.blue : Colors.grey,
              ),
              const SizedBox(width: 8),
              Text(
                card.title,
                style: TextStyle(
                  fontSize: 18,
                  fontWeight: FontWeight.bold,
                  color: canNavigate ? Colors.black87 : Colors.grey,
                ),
              ),
              const Spacer(),
              _buildShortcutHint(card, canNavigate),
            ],
          ),
        ),
      ),
    );
  }

  Widget _buildShortcutHint(FeatureCard card, bool canNavigate) {
    return Container(
      padding: const EdgeInsets.symmetric(horizontal: 8, vertical: 4),
      decoration: BoxDecoration(
        color: canNavigate ? Colors.blue.shade50 : Colors.grey.shade300,
        border: Border.all(
          color: canNavigate ? Colors.blue.shade200 : Colors.grey.shade400,
        ),
        borderRadius: BorderRadius.circular(6),
      ),
      child: Text(
        '按 ${card.shortcut} 进入',
        style: TextStyle(
          fontSize: 13,
          fontWeight: FontWeight.w700,
          color: canNavigate ? Colors.blue.shade800 : Colors.grey.shade600,
        ),
      ),
    );
  }
}