import 'dart:math' as math;
import 'package:flutter/material.dart';
import 'package:go_router/go_router.dart';
import 'package:permission_handler/permission_handler.dart';
import '../../../core/constants/app_colors.dart';
import '../../../core/constants/app_typography.dart';
import '../../../core/constants/app_constants.dart';
import '../../../core/services/permission_service.dart';

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

  @override
  State<SplashScreen> createState() => _SplashScreenState();
}

class _SplashScreenState extends State<SplashScreen>
    with TickerProviderStateMixin {
  late List<AnimationController> _foodControllers;
  late AnimationController _questionMarkController;
  late AnimationController _centerIconController;
  List<Offset>? _iconPositions;
  Size? _lastScreenSize;

  final List<IconData> foodIcons = [
    Icons.rice_bowl,
    Icons.ramen_dining,
    Icons.lunch_dining,
    Icons.fastfood,
    Icons.local_pizza,
    Icons.cake,
    Icons.coffee,
    Icons.icecream,
    Icons.bakery_dining,
  ];

  @override
  void initState() {
    super.initState();
    _initializeAnimations();
    _navigateToHome();
  }

  void _initializeAnimations() {
    // 음식 아이콘 애니메이션 (여러 개)
    _foodControllers = List.generate(
      foodIcons.length,
      (index) => AnimationController(
        duration: Duration(seconds: 2 + index % 3),
        vsync: this,
      )..repeat(reverse: true),
    );

    // 물음표 애니메이션
    _questionMarkController = AnimationController(
      duration: const Duration(milliseconds: 500),
      vsync: this,
    )..repeat();

    // 중앙 아이콘 애니메이션
    _centerIconController = AnimationController(
      duration: const Duration(seconds: 1),
      vsync: this,
    )..repeat(reverse: true);
  }

  List<Offset> _generateIconPositions(Size screenSize) {
    final random = math.Random();
    const iconSize = 40.0;
    const maxScale = 1.5;
    const margin = iconSize * maxScale;
    const overlapThreshold = 0.3;
    final effectiveSize = iconSize * maxScale;
    final center = Offset(screenSize.width / 2, screenSize.height / 2);
    final centerSafeRadius =
        math.min(screenSize.width, screenSize.height) * 0.18;

    Offset randomPosition() {
      final x =
          margin +
          random.nextDouble() * (screenSize.width - margin * 2).clamp(1, 9999);
      final y =
          margin +
          random.nextDouble() * (screenSize.height - margin * 2).clamp(1, 9999);
      return Offset(x, y);
    }

    final positions = <Offset>[];
    var attempts = 0;
    const maxAttempts = 500;

    while (positions.length < foodIcons.length && attempts < maxAttempts) {
      attempts++;
      final candidate = randomPosition();
      if ((candidate - center).distance < centerSafeRadius) {
        continue;
      }
      final hasHeavyOverlap = positions.any(
        (p) => _isOverlapTooHigh(p, candidate, effectiveSize, overlapThreshold),
      );
      if (hasHeavyOverlap) {
        continue;
      }
      positions.add(candidate);
    }

    while (positions.length < foodIcons.length) {
      positions.add(randomPosition());
    }

    return positions;
  }

  bool _isOverlapTooHigh(Offset a, Offset b, double size, double maxRatio) {
    final dx = (a.dx - b.dx).abs();
    final dy = (a.dy - b.dy).abs();
    final overlapX = math.max(0.0, size - dx);
    final overlapY = math.max(0.0, size - dy);
    final overlapArea = overlapX * overlapY;
    final maxArea = size * size;
    if (maxArea == 0) return false;
    return overlapArea / maxArea > maxRatio;
  }

  @override
  Widget build(BuildContext context) {
    final isDark = Theme.of(context).brightness == Brightness.dark;

    return Scaffold(
      backgroundColor: isDark
          ? AppColors.darkBackground
          : AppColors.lightBackground,
      body: Stack(
        children: [
          // 랜덤 위치 음식 아이콘들
          ..._buildFoodIcons(),

          // 중앙 컨텐츠
          Center(
            child: Column(
              mainAxisAlignment: MainAxisAlignment.center,
              children: [
                // 선택 아이콘
                ScaleTransition(
                  scale: Tween(begin: 0.8, end: 1.2).animate(
                    CurvedAnimation(
                      parent: _centerIconController,
                      curve: Curves.easeInOut,
                    ),
                  ),
                  child: Icon(
                    Icons.restaurant_menu,
                    size: 80,
                    color: isDark
                        ? AppColors.darkPrimary
                        : AppColors.lightPrimary,
                  ),
                ),
                const SizedBox(height: 20),

                // 앱 타이틀
                Row(
                  mainAxisAlignment: MainAxisAlignment.center,
                  children: [
                    Text('오늘 뭐 먹Z', style: AppTypography.heading1(isDark)),
                    AnimatedBuilder(
                      animation: _questionMarkController,
                      builder: (context, child) {
                        final questionMarks =
                            '?' *
                            (((_questionMarkController.value * 3).floor() % 3) +
                                1);
                        return Text(
                          questionMarks,
                          style: AppTypography.heading1(isDark),
                        );
                      },
                    ),
                  ],
                ),
              ],
            ),
          ),

          // 하단 카피라이트
          Positioned(
            bottom: 30,
            left: 0,
            right: 0,
            child: Text(
              AppConstants.appCopyright,
              style: AppTypography.caption(isDark).copyWith(
                color:
                    (isDark
                            ? AppColors.darkTextSecondary
                            : AppColors.lightTextSecondary)
                        .withOpacity(0.5),
              ),
              textAlign: TextAlign.center,
            ),
          ),
        ],
      ),
    );
  }

  List<Widget> _buildFoodIcons() {
    final screenSize = MediaQuery.of(context).size;
    final sameSize =
        _lastScreenSize != null &&
        (_lastScreenSize!.width - screenSize.width).abs() < 1 &&
        (_lastScreenSize!.height - screenSize.height).abs() < 1;
    if (_iconPositions == null || !sameSize) {
      _iconPositions = _generateIconPositions(screenSize);
      _lastScreenSize = screenSize;
    }

    return List.generate(foodIcons.length, (index) {
      final position = _iconPositions![index];

      return Positioned(
        left: position.dx,
        top: position.dy,
        child: FadeTransition(
          opacity: Tween(begin: 0.2, end: 0.8).animate(
            CurvedAnimation(
              parent: _foodControllers[index],
              curve: Curves.easeInOut,
            ),
          ),
          child: ScaleTransition(
            scale: Tween(begin: 0.5, end: 1.5).animate(
              CurvedAnimation(
                parent: _foodControllers[index],
                curve: Curves.easeInOut,
              ),
            ),
            child: Icon(
              foodIcons[index],
              size: 40,
              color: AppColors.lightPrimary.withOpacity(0.3),
            ),
          ),
        ),
      );
    });
  }

  void _navigateToHome() {
    // 권한 요청이 지연되어도 스플래시(Splash) 화면이 멈추지 않도록 최대 5초만 대기한다.
    final permissionFuture = _ensurePermissions().timeout(
      const Duration(seconds: 5),
      onTimeout: () {},
    );

    Future.wait([
      permissionFuture,
      Future.delayed(AppConstants.splashAnimationDuration),
    ]).whenComplete(() {
      if (!mounted) return;
      context.go('/home');
    });
  }

  Future<void> _ensurePermissions() async {
    try {
      await Permission.notification.request();
      await Permission.location.request();
      await PermissionService.checkAndRequestBluetoothPermission();
    } catch (_) {
      // 권한 요청 중 예외가 발생해도 앱 흐름을 막지 않는다.
    }
  }

  @override
  void dispose() {
    for (final controller in _foodControllers) {
      controller.dispose();
    }
    _questionMarkController.dispose();
    _centerIconController.dispose();
    super.dispose();
  }
}