import 'dart:async';
import 'dart:convert';
import 'dart:math';

import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:lunchpick/core/constants/app_colors.dart';
import 'package:lunchpick/core/constants/app_typography.dart';
import 'package:lunchpick/core/services/permission_service.dart';
import 'package:lunchpick/domain/entities/restaurant.dart';
import 'package:lunchpick/domain/entities/share_device.dart';
import 'package:lunchpick/presentation/providers/ad_provider.dart';
import 'package:lunchpick/presentation/providers/bluetooth_provider.dart';
import 'package:lunchpick/presentation/providers/restaurant_provider.dart';
import 'package:uuid/uuid.dart';

class ShareScreen extends ConsumerStatefulWidget {
  const ShareScreen({super.key});

  @override
  ConsumerState<ShareScreen> createState() => _ShareScreenState();
}

class _ShareScreenState extends ConsumerState<ShareScreen> {
  String? _shareCode;
  bool _isScanning = false;
  List<ShareDevice>? _nearbyDevices;
  StreamSubscription<String>? _dataSubscription;
  final _uuid = const Uuid();

  @override
  void initState() {
    super.initState();
    final bluetoothService = ref.read(bluetoothServiceProvider);
    _dataSubscription = bluetoothService.onDataReceived.listen((payload) {
      _handleIncomingData(payload);
    });
  }

  @override
  void dispose() {
    _dataSubscription?.cancel();
    ref.read(bluetoothServiceProvider).stopListening();
    super.dispose();
  }

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

    return Scaffold(
      backgroundColor: isDark
          ? AppColors.darkBackground
          : AppColors.lightBackground,
      appBar: AppBar(
        title: const Text('리스트 공유'),
        backgroundColor: isDark
            ? AppColors.darkPrimary
            : AppColors.lightPrimary,
        foregroundColor: Colors.white,
        elevation: 0,
      ),
      body: SingleChildScrollView(
        padding: const EdgeInsets.all(16),
        child: Column(
          children: [
            // 공유받기 섹션
            Card(
              color: isDark ? AppColors.darkSurface : AppColors.lightSurface,
              elevation: 2,
              shape: RoundedRectangleBorder(
                borderRadius: BorderRadius.circular(16),
              ),
              child: Padding(
                padding: const EdgeInsets.all(24),
                child: Column(
                  children: [
                    Container(
                      padding: const EdgeInsets.all(16),
                      decoration: BoxDecoration(
                        color: AppColors.lightPrimary.withOpacity(0.1),
                        shape: BoxShape.circle,
                      ),
                      child: const Icon(
                        Icons.download_rounded,
                        size: 48,
                        color: AppColors.lightPrimary,
                      ),
                    ),
                    const SizedBox(height: 16),
                    Text('리스트 공유받기', style: AppTypography.heading2(isDark)),
                    const SizedBox(height: 8),
                    Text(
                      '다른 사람의 맛집 리스트를 받아보세요',
                      style: AppTypography.body2(isDark),
                      textAlign: TextAlign.center,
                    ),
                    const SizedBox(height: 20),
                    if (_shareCode != null) ...[
                      Container(
                        padding: const EdgeInsets.symmetric(
                          horizontal: 24,
                          vertical: 16,
                        ),
                        decoration: BoxDecoration(
                          color: AppColors.lightPrimary.withOpacity(0.1),
                          borderRadius: BorderRadius.circular(12),
                          border: Border.all(
                            color: AppColors.lightPrimary.withOpacity(0.3),
                            width: 2,
                          ),
                        ),
                        child: Text(
                          _shareCode!,
                          style: const TextStyle(
                            fontSize: 36,
                            fontWeight: FontWeight.bold,
                            letterSpacing: 6,
                            color: AppColors.lightPrimary,
                          ),
                        ),
                      ),
                      const SizedBox(height: 12),
                      Text(
                        '이 코드를 상대방에게 알려주세요',
                        style: AppTypography.caption(isDark),
                      ),
                      const SizedBox(height: 16),
                      TextButton.icon(
                        onPressed: () {
                          setState(() {
                            _shareCode = null;
                          });
                          ref.read(bluetoothServiceProvider).stopListening();
                        },
                        icon: const Icon(Icons.close),
                        label: const Text('취소'),
                        style: TextButton.styleFrom(
                          foregroundColor: AppColors.lightError,
                        ),
                      ),
                    ] else
                      ElevatedButton.icon(
                        onPressed: () {
                          _generateShareCode();
                        },
                        icon: const Icon(Icons.qr_code),
                        label: const Text('공유 코드 생성'),
                        style: ElevatedButton.styleFrom(
                          backgroundColor: AppColors.lightPrimary,
                          foregroundColor: Colors.white,
                          padding: const EdgeInsets.symmetric(
                            horizontal: 24,
                            vertical: 12,
                          ),
                          shape: RoundedRectangleBorder(
                            borderRadius: BorderRadius.circular(8),
                          ),
                        ),
                      ),
                  ],
                ),
              ),
            ),

            const SizedBox(height: 16),

            // 공유하기 섹션
            Card(
              color: isDark ? AppColors.darkSurface : AppColors.lightSurface,
              elevation: 2,
              shape: RoundedRectangleBorder(
                borderRadius: BorderRadius.circular(16),
              ),
              child: Padding(
                padding: const EdgeInsets.all(24),
                child: Column(
                  children: [
                    Container(
                      padding: const EdgeInsets.all(16),
                      decoration: BoxDecoration(
                        color: AppColors.lightSecondary.withOpacity(0.1),
                        shape: BoxShape.circle,
                      ),
                      child: const Icon(
                        Icons.upload_rounded,
                        size: 48,
                        color: AppColors.lightSecondary,
                      ),
                    ),
                    const SizedBox(height: 16),
                    Text('내 리스트 공유하기', style: AppTypography.heading2(isDark)),
                    const SizedBox(height: 8),
                    Text(
                      '내 맛집 리스트를 다른 사람과 공유하세요',
                      style: AppTypography.body2(isDark),
                      textAlign: TextAlign.center,
                    ),
                    const SizedBox(height: 20),
                    if (_isScanning && _nearbyDevices != null) ...[
                      Container(
                        constraints: const BoxConstraints(maxHeight: 220),
                        child: _nearbyDevices!.isEmpty
                            ? Column(
                                children: [
                                  const CircularProgressIndicator(
                                    color: AppColors.lightSecondary,
                                  ),
                                  const SizedBox(height: 16),
                                  Text(
                                    '주변 기기를 검색 중...',
                                    style: AppTypography.caption(isDark),
                                  ),
                                ],
                              )
                            : ListView.builder(
                                itemCount: _nearbyDevices!.length,
                                shrinkWrap: true,
                                itemBuilder: (context, index) {
                                  final device = _nearbyDevices![index];
                                  return Card(
                                    margin: const EdgeInsets.only(bottom: 8),
                                    child: ListTile(
                                      leading: const Icon(
                                        Icons.phone_android,
                                        color: AppColors.lightSecondary,
                                      ),
                                      title: Text(
                                        device.code,
                                        style: AppTypography.body1(
                                          isDark,
                                        ).copyWith(fontWeight: FontWeight.bold),
                                      ),
                                      subtitle: Text(
                                        '기기 ID: ${device.deviceId}',
                                      ),
                                      trailing: const Icon(
                                        Icons.send,
                                        color: AppColors.lightSecondary,
                                      ),
                                      onTap: () {
                                        _sendList(device.code);
                                      },
                                    ),
                                  );
                                },
                              ),
                      ),
                      const SizedBox(height: 16),
                      TextButton.icon(
                        onPressed: () {
                          setState(() {
                            _isScanning = false;
                            _nearbyDevices = null;
                          });
                        },
                        icon: const Icon(Icons.stop),
                        label: const Text('스캔 중지'),
                        style: TextButton.styleFrom(
                          foregroundColor: AppColors.lightError,
                        ),
                      ),
                    ] else
                      ElevatedButton.icon(
                        onPressed: () {
                          _scanDevices();
                        },
                        icon: const Icon(Icons.radar),
                        label: const Text('주변 기기 스캔'),
                        style: ElevatedButton.styleFrom(
                          backgroundColor: AppColors.lightSecondary,
                          foregroundColor: Colors.white,
                          padding: const EdgeInsets.symmetric(
                            horizontal: 24,
                            vertical: 12,
                          ),
                          shape: RoundedRectangleBorder(
                            borderRadius: BorderRadius.circular(8),
                          ),
                        ),
                      ),
                  ],
                ),
              ),
            ),
          ],
        ),
      ),
    );
  }

  Future<void> _generateShareCode() async {
    final adService = ref.read(adServiceProvider);
    final adWatched = await adService.showInterstitialAd(context);
    if (!mounted) return;
    if (!adWatched) {
      _showErrorSnackBar('광고를 끝까지 시청해야 공유 코드를 생성할 수 있어요.');
      return;
    }

    final random = Random();
    final code = List.generate(6, (_) => random.nextInt(10)).join();

    setState(() {
      _shareCode = code;
    });

    await ref.read(bluetoothServiceProvider).startListening(code);
    _showSuccessSnackBar('공유 코드가 생성되었습니다.');
  }

  Future<void> _scanDevices() async {
    final hasPermission =
        await PermissionService.checkAndRequestBluetoothPermission();
    if (!hasPermission) {
      if (!mounted) return;
      _showErrorSnackBar('블루투스 권한이 필요합니다.');
      return;
    }

    setState(() {
      _isScanning = true;
      _nearbyDevices = [];
    });

    try {
      final devices = await ref
          .read(bluetoothServiceProvider)
          .scanNearbyDevices();
      if (!mounted) return;
      setState(() {
        _nearbyDevices = devices;
      });
    } catch (e) {
      if (!mounted) return;
      setState(() {
        _isScanning = false;
      });
      _showErrorSnackBar('스캔 중 오류가 발생했습니다.');
    }
  }

  Future<void> _sendList(String targetCode) async {
    final restaurants = await ref.read(restaurantListProvider.future);
    if (!mounted) return;

    _showLoadingDialog('리스트 전송 중...');
    try {
      await ref
          .read(bluetoothServiceProvider)
          .sendRestaurantList(targetCode, restaurants);
      if (!mounted) return;
      Navigator.pop(context);
      _showSuccessSnackBar('리스트 전송 완료!');
      setState(() {
        _isScanning = false;
        _nearbyDevices = null;
      });
    } catch (e) {
      if (!mounted) return;
      Navigator.pop(context);
      _showErrorSnackBar('전송 실패: $e');
    }
  }

  Future<void> _handleIncomingData(String payload) async {
    if (!mounted) return;
    final adWatched = await ref
        .read(adServiceProvider)
        .showInterstitialAd(context);
    if (!mounted) return;
    if (!adWatched) {
      _showErrorSnackBar('광고를 시청해야 리스트를 받을 수 있어요.');
      return;
    }

    try {
      final restaurants = _parseReceivedData(payload);
      await _mergeRestaurantList(restaurants);
    } catch (_) {
      _showErrorSnackBar('전송된 데이터를 처리하는 데 실패했습니다.');
    }
  }

  List<Restaurant> _parseReceivedData(String data) {
    final jsonList = jsonDecode(data) as List<dynamic>;
    return jsonList
        .map((item) => _restaurantFromJson(item as Map<String, dynamic>))
        .toList();
  }

  Restaurant _restaurantFromJson(Map<String, dynamic> json) {
    return Restaurant(
      id: json['id'] as String,
      name: json['name'] as String,
      category: json['category'] as String,
      subCategory: json['subCategory'] as String,
      description: json['description'] as String?,
      phoneNumber: json['phoneNumber'] as String?,
      roadAddress: json['roadAddress'] as String,
      jibunAddress: json['jibunAddress'] as String,
      latitude: (json['latitude'] as num).toDouble(),
      longitude: (json['longitude'] as num).toDouble(),
      lastVisitDate: json['lastVisitDate'] != null
          ? DateTime.parse(json['lastVisitDate'] as String)
          : null,
      source: DataSource.values.firstWhere(
        (source) =>
            source.name ==
            (json['source'] as String? ?? DataSource.USER_INPUT.name),
        orElse: () => DataSource.USER_INPUT,
      ),
      createdAt: DateTime.parse(json['createdAt'] as String),
      updatedAt: DateTime.parse(json['updatedAt'] as String),
      naverPlaceId: json['naverPlaceId'] as String?,
      naverUrl: json['naverUrl'] as String?,
      businessHours: json['businessHours'] as String?,
      lastVisited: json['lastVisited'] != null
          ? DateTime.parse(json['lastVisited'] as String)
          : null,
      visitCount: (json['visitCount'] as num?)?.toInt() ?? 0,
    );
  }

  Future<void> _mergeRestaurantList(List<Restaurant> receivedList) async {
    final currentList = await ref.read(restaurantListProvider.future);
    final notifier = ref.read(restaurantNotifierProvider.notifier);

    final newRestaurants = <Restaurant>[];
    for (final restaurant in receivedList) {
      final exists = currentList.any(
        (existing) =>
            existing.name == restaurant.name &&
            existing.roadAddress == restaurant.roadAddress,
      );
      if (!exists) {
        newRestaurants.add(
          restaurant.copyWith(
            id: _uuid.v4(),
            createdAt: DateTime.now(),
            updatedAt: DateTime.now(),
            source: DataSource.USER_INPUT,
          ),
        );
      }
    }

    for (final restaurant in newRestaurants) {
      await notifier.addRestaurantDirect(restaurant);
    }

    if (!mounted) return;
    if (newRestaurants.isEmpty) {
      _showSuccessSnackBar('이미 등록된 맛집과 동일한 항목만 전송되었습니다.');
    } else {
      _showSuccessSnackBar('${newRestaurants.length}개의 새로운 맛집이 추가되었습니다!');
    }

    setState(() {
      _shareCode = null;
    });
    ref.read(bluetoothServiceProvider).stopListening();
  }

  void _showLoadingDialog(String message) {
    final isDark = Theme.of(context).brightness == Brightness.dark;

    showDialog(
      context: context,
      barrierDismissible: false,
      builder: (context) => Dialog(
        backgroundColor: isDark
            ? AppColors.darkSurface
            : AppColors.lightSurface,
        child: Padding(
          padding: const EdgeInsets.all(20),
          child: Row(
            mainAxisSize: MainAxisSize.min,
            children: [
              const CircularProgressIndicator(color: AppColors.lightPrimary),
              const SizedBox(width: 20),
              Flexible(
                child: Text(message, style: AppTypography.body2(isDark)),
              ),
            ],
          ),
        ),
      ),
    );
  }

  void _showSuccessSnackBar(String message) {
    if (!mounted) return;
    ScaffoldMessenger.of(context).showSnackBar(
      SnackBar(content: Text(message), backgroundColor: AppColors.lightPrimary),
    );
  }

  void _showErrorSnackBar(String message) {
    if (!mounted) return;
    ScaffoldMessenger.of(context).showSnackBar(
      SnackBar(content: Text(message), backgroundColor: AppColors.lightError),
    );
  }
}