import 'dart:async';
import 'dart:ui';

import 'package:flutter/material.dart';
import 'package:firebase_core/firebase_core.dart';
import 'package:firebase_messaging/firebase_messaging.dart';
import 'package:flutter/foundation.dart';
import 'app/injection_container.dart';
import 'app/app.dart';
import 'core/constants/app_constants.dart';
import 'core/utils/init_guard.dart';

@pragma('vm:entry-point')
Future<void> _firebaseMessagingBackgroundHandler(RemoteMessage message) async {
  await Firebase.initializeApp();
}

Future<void> main() async {
  await runZonedGuarded(
    () async {
      WidgetsFlutterBinding.ensureInitialized();
      _installGlobalErrorUi();
      await AppConstants.clearServerUrl();

      if (!kIsWeb) {
        final firebaseApp = await ignoreInitFailure(
          () => Firebase.initializeApp(),
          label: 'Firebase init',
        );
        if (firebaseApp != null) {
          FirebaseMessaging.onBackgroundMessage(
            _firebaseMessagingBackgroundHandler,
          );
        }
      }

      try {
        await initDependencies();
      } catch (error, stackTrace) {
        debugPrint('WalkGuide startup failed: $error\n$stackTrace');
        runApp(WalkGuideFatalApp(error: error, stackTrace: stackTrace));
        return;
      }

      runApp(const WalkGuideApp());
    },
    (error, stackTrace) {
      debugPrint('WalkGuide uncaught error: $error\n$stackTrace');
      runApp(WalkGuideFatalApp(error: error, stackTrace: stackTrace));
    },
  );
}

void _installGlobalErrorUi() {
  FlutterError.onError = (details) {
    FlutterError.presentError(details);
    debugPrint('WalkGuide Flutter error: ${details.exceptionAsString()}');
  };

  PlatformDispatcher.instance.onError = (error, stackTrace) {
    debugPrint('WalkGuide platform error: $error\n$stackTrace');
    return true;
  };

  ErrorWidget.builder = (details) {
    return WalkGuideErrorPanel(
      title: 'WalkGuide UI Error',
      message:
          'A screen failed to render. Please report this message to the developer.',
      details: details.exceptionAsString(),
    );
  };
}

class WalkGuideFatalApp extends StatelessWidget {
  final Object error;
  final StackTrace? stackTrace;

  const WalkGuideFatalApp({
    super.key,
    required this.error,
    this.stackTrace,
  });

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      home: WalkGuideErrorPanel(
        title: 'WalkGuide Startup Error',
        message:
            'The app could not finish startup. Please report this screen to the developer.',
        details: error.toString(),
        stackTrace: stackTrace?.toString(),
      ),
    );
  }
}

class WalkGuideErrorPanel extends StatelessWidget {
  final String title;
  final String message;
  final String details;
  final String? stackTrace;

  const WalkGuideErrorPanel({
    super.key,
    required this.title,
    required this.message,
    required this.details,
    this.stackTrace,
  });

  @override
  Widget build(BuildContext context) {
    final textTheme = Theme.of(context).textTheme;
    return Scaffold(
      backgroundColor: const Color(0xFFF8FAFC),
      body: SafeArea(
        child: Center(
          child: SingleChildScrollView(
            padding: const EdgeInsets.all(24),
            child: ConstrainedBox(
              constraints: const BoxConstraints(maxWidth: 520),
              child: DecoratedBox(
                decoration: BoxDecoration(
                  color: Colors.white,
                  borderRadius: BorderRadius.circular(16),
                  border: Border.all(color: const Color(0xFFE2E8F0)),
                  boxShadow: const [
                    BoxShadow(
                      blurRadius: 24,
                      offset: Offset(0, 12),
                      color: Color(0x1A0F172A),
                    ),
                  ],
                ),
                child: Padding(
                  padding: const EdgeInsets.all(22),
                  child: Column(
                    mainAxisSize: MainAxisSize.min,
                    crossAxisAlignment: CrossAxisAlignment.start,
                    children: [
                      const Icon(
                        Icons.error_outline,
                        color: Color(0xFFDC2626),
                        size: 42,
                      ),
                      const SizedBox(height: 16),
                      Text(
                        title,
                        style: textTheme.headlineSmall?.copyWith(
                          fontWeight: FontWeight.w800,
                          color: const Color(0xFF0F172A),
                        ),
                      ),
                      const SizedBox(height: 8),
                      Text(
                        message,
                        style: textTheme.bodyMedium?.copyWith(
                          color: const Color(0xFF475569),
                        ),
                      ),
                      const SizedBox(height: 18),
                      Container(
                        width: double.infinity,
                        padding: const EdgeInsets.all(14),
                        decoration: BoxDecoration(
                          color: const Color(0xFFF1F5F9),
                          borderRadius: BorderRadius.circular(10),
                          border: Border.all(color: const Color(0xFFE2E8F0)),
                        ),
                        child: SelectableText(
                          _formatDetails(),
                          style: const TextStyle(
                            fontFamily: 'monospace',
                            fontSize: 12,
                            color: Color(0xFF334155),
                          ),
                        ),
                      ),
                      const SizedBox(height: 16),
                      const Text(
                        'Tip: close the app and open it again after fixing the configuration.',
                        style: TextStyle(
                          color: Color(0xFF64748B),
                          fontSize: 12,
                        ),
                      ),
                    ],
                  ),
                ),
              ),
            ),
          ),
        ),
      ),
    );
  }

  String _formatDetails() {
    final stack = stackTrace;
    if (stack == null || stack.isEmpty) return details;
    final shortStack = stack.split('\n').take(8).join('\n');
    return '$details\n\n$shortStack';
  }
}