import 'package:flutter/material.dart';
import 'config/strings.dart';
import 'config/title_server_config.dart';
import 'services/api_service.dart';
import 'services/file_picker_service.dart';
import 'services/qr_service.dart';
import 'pages/home_page.dart';
import 'pages/settings_page.dart';

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await TitleServerConfigHolder().init();
  runApp(const MyApp());
}

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

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: AppStrings.appTitle,
      debugShowCheckedModeBanner: false,
      themeMode: ThemeMode.system,
      theme: ThemeData(
        colorScheme: ColorScheme.fromSeed(
          seedColor: Colors.blue,
          brightness: Brightness.light,
        ),
      ),
      darkTheme: ThemeData(
        colorScheme: ColorScheme.fromSeed(
          seedColor: Colors.blue,
          brightness: Brightness.dark,
        ),
      ),
      home: const LoginPage(),
    );
  }
}

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

  @override
  State<LoginPage> createState() => _LoginPageState();
}

class _LoginPageState extends State<LoginPage> {
  final _qrController = TextEditingController();
  final _apiService = ApiService();
  String _qrCode = '';
  bool _loading = false;

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

  void _onQRContentChanged(String value) {
    setState(() {
      _qrCode = _apiService.extractQRCode(value.trim());
    });
  }

  Future<void> _onUploadQR() async {
    try {
      final bytes = await pickImageBytes();
      if (bytes == null) return;

      final result = await decodeQRFromBytes(bytes);

      if (result != null && result.isNotEmpty) {
        _qrController.text = result;
        setState(() {
          _qrCode = _apiService.extractQRCode(result);
        });
        if (mounted) {
          ScaffoldMessenger.of(context).showSnackBar(
            const SnackBar(content: Text(AppStrings.qrScanSuccess)),
          );
        }
      } else {
        if (mounted) {
          ScaffoldMessenger.of(context).showSnackBar(
            const SnackBar(content: Text(AppStrings.qrScanFailed)),
          );
        }
      }
    } catch (e) {
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(content: Text('${AppStrings.qrScanError}: $e')),
        );
      }
    }
  }

  Future<void> _onLogin() async {
    if (_qrCode.isEmpty) return;

    setState(() => _loading = true);

    try {
      final result = await _apiService.login(_qrCode);

      if (!mounted) return;

      if (result.success) {
        if (!mounted) return;
        Navigator.of(context).push(
          MaterialPageRoute(
            builder: (_) => HomePage(
              userId: result.userId,
              token: result.token,
            ),
          ),
        );
      } else {
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(content: Text('${AppStrings.loginFailed} (errorID: ${result.errorId})')),
        );
      }
    } catch (e) {
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(content: Text('${AppStrings.requestFailed}: $e')),
        );
      }
    } finally {
      if (mounted) {
        setState(() => _loading = false);
      }
    }
  }

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

    return Scaffold(
      appBar: AppBar(
        title: const Text(AppStrings.appTitle),
        actions: [
          IconButton(
            icon: const Icon(Icons.settings),
            tooltip: AppStrings.settingsTooltip,
            onPressed: () {
              Navigator.of(context).push(
                MaterialPageRoute(builder: (_) => const SettingsPage()),
              );
            },
          ),
        ],
      ),
      body: Center(
        child: SingleChildScrollView(
          padding: const EdgeInsets.symmetric(horizontal: 24, vertical: 48),
          child: ConstrainedBox(
            constraints: const BoxConstraints(maxWidth: 440),
            child: Column(
              mainAxisSize: MainAxisSize.min,
              children: [
                Icon(
                  Icons.qr_code_scanner,
                  size: 64,
                  color: theme.colorScheme.primary,
                ),
                const SizedBox(height: 16),
                Text(
                  AppStrings.appTitle,
                  style: theme.textTheme.headlineMedium?.copyWith(
                    fontWeight: FontWeight.bold,
                    color: theme.colorScheme.primary,
                  ),
                ),
                const SizedBox(height: 8),
                Text(
                  AppStrings.loginSubtitle,
                  style: theme.textTheme.bodyMedium?.copyWith(
                    color: theme.colorScheme.onSurfaceVariant,
                  ),
                ),
                const SizedBox(height: 40),

                Card(
                  elevation: 0,
                  shape: RoundedRectangleBorder(
                    borderRadius: BorderRadius.circular(16),
                    side: BorderSide(
                      color: theme.colorScheme.outline.withValues(alpha: 0.3),
                    ),
                  ),
                  child: Padding(
                    padding: const EdgeInsets.all(20),
                    child: Column(
                      crossAxisAlignment: CrossAxisAlignment.start,
                      children: [
                        Row(
                          children: [
                            Icon(
                              Icons.key,
                              size: 18,
                              color: theme.colorScheme.primary,
                            ),
                            const SizedBox(width: 8),
                            Text(
                              AppStrings.qrCodeToken,
                              style: theme.textTheme.labelLarge?.copyWith(
                                color: theme.colorScheme.primary,
                                fontWeight: FontWeight.w600,
                              ),
                            ),
                          ],
                        ),
                        const SizedBox(height: 12),
                        TextField(
                          controller: _qrController,
                          maxLines: 3,
                          onChanged: _onQRContentChanged,
                          style: theme.textTheme.bodyMedium?.copyWith(
                            fontFamily: 'monospace',
                            letterSpacing: 0.5,
                          ),
                          decoration: InputDecoration(
                            hintText: AppStrings.qrHint,
                            hintStyle: theme.textTheme.bodyMedium?.copyWith(
                              color: theme.colorScheme.onSurfaceVariant
                                  .withValues(alpha: 0.5),
                              fontFamily: 'monospace',
                            ),
                            border: OutlineInputBorder(
                              borderRadius: BorderRadius.circular(10),
                            ),
                            contentPadding: const EdgeInsets.all(14),
                          ),
                        ),
                      ],
                    ),
                  ),
                ),

                if (_qrCode.isNotEmpty) ...[
                  const SizedBox(height: 12),
                  Container(
                    width: double.infinity,
                    padding: const EdgeInsets.all(12),
                    decoration: BoxDecoration(
                      color: theme.colorScheme.surfaceContainerHighest
                          .withValues(alpha: 0.5),
                      borderRadius: BorderRadius.circular(10),
                    ),
                    child: Column(
                      crossAxisAlignment: CrossAxisAlignment.start,
                      children: [
                        Text(
                          AppStrings.qrParsedResult,
                          style: theme.textTheme.labelSmall?.copyWith(
                            color: theme.colorScheme.onSurfaceVariant,
                          ),
                        ),
                        const SizedBox(height: 6),
                        Text(
                          _qrCode,
                          style: theme.textTheme.bodySmall?.copyWith(
                            fontFamily: 'monospace',
                            color: theme.colorScheme.onSurface,
                          ),
                        ),
                      ],
                    ),
                  ),
                ],

                const SizedBox(height: 28),

                Row(
                  children: [
                    Expanded(
                      child: OutlinedButton.icon(
                        onPressed: _loading ? null : _onUploadQR,
                        icon: const Icon(Icons.image, size: 20),
                        label: const Text(AppStrings.uploadQR),
                        style: OutlinedButton.styleFrom(
                          padding: const EdgeInsets.symmetric(vertical: 14),
                          shape: RoundedRectangleBorder(
                            borderRadius: BorderRadius.circular(12),
                          ),
                        ),
                      ),
                    ),
                    const SizedBox(width: 16),
                    Expanded(
                      child: FilledButton.icon(
                        onPressed:
                            (_qrCode.isNotEmpty && !_loading) ? _onLogin : null,
                        icon: _loading
                            ? const SizedBox(
                                width: 20,
                                height: 20,
                                child: CircularProgressIndicator(
                                  strokeWidth: 2,
                                  color: Colors.white,
                                ),
                              )
                            : const Icon(Icons.arrow_forward, size: 20),
                        label: Text(_loading ? AppStrings.loggingIn : AppStrings.login),
                        style: FilledButton.styleFrom(
                          padding: const EdgeInsets.symmetric(vertical: 14),
                          shape: RoundedRectangleBorder(
                            borderRadius: BorderRadius.circular(12),
                          ),
                        ),
                      ),
                    ),
                  ],
                ),
              ],
            ),
          ),
        ),
      ),
    );
  }
}