import 'dart:async';
import 'package:flutter/foundation.dart';
import 'package:flutter_blue_plus/flutter_blue_plus.dart';
import 'package:get/get.dart';
import '../../core/utils/logger.dart';
import 'dart:io' show Platform;
import 'package:permission_handler/permission_handler.dart';

/// 蓝牙设备服务，用于发现和管理蓝牙设备
class BluetoothService extends GetxService {
  static BluetoothService get to => Get.find<BluetoothService>();

  // 单例实例
  static final BluetoothService _instance = BluetoothService._internal();
  factory BluetoothService() => _instance;
  BluetoothService._internal();

  // 设备状态
  final _isAvailable = false.obs;
  final _isOn = false.obs;
  
  // 已连接的设备
  final _connectedDevices = <BluetoothDevice>[].obs;
  
  // 扫描状态
  final _isScanning = false.obs;
  
  // 扫描结果
  final _scanResults = <ScanResult>[].obs;
  
  // 当前选中的设备
  final _selectedDevice = Rx<BluetoothDevice?>(null);
  
  // 连接状态
  final _connectionState = Rx<BluetoothConnectionState>(BluetoothConnectionState.disconnected);
  
  // 存储最后连接的设备信息，供其他控制器使用
  final _lastConnectedDeviceInfo = Rx<Map<String, dynamic>>({});
  
  // 订阅
  StreamSubscription? _stateSubscription;
  StreamSubscription? _scanSubscription;
  StreamSubscription? _connectionSubscription;

  // 权限状态
  final _permissionsGranted = false.obs;
  bool get permissionsGranted => _permissionsGranted.value;
  
  // Getters
  bool get isAvailable => _isAvailable.value;
  bool get isOn => _isOn.value;
  bool get isScanning => _isScanning.value;
  List<BluetoothDevice> get connectedDevices => _connectedDevices;
  List<ScanResult> get scanResults => _scanResults;
  BluetoothDevice? get selectedDevice => _selectedDevice.value;
  BluetoothConnectionState get connectionState => _connectionState.value;
  Map<String, dynamic> get lastConnectedDeviceInfo => _lastConnectedDeviceInfo.value;
  
  // Observable getters (for reactive programming)
  RxBool get isAvailableObs => _isAvailable;
  RxBool get isOnObs => _isOn;
  RxList<BluetoothDevice> get connectedDevicesObs => _connectedDevices;
  RxList<ScanResult> get scanResultsObs => _scanResults;
  Rx<BluetoothDevice?> get selectedDeviceObs => _selectedDevice;
  Rx<BluetoothConnectionState> get connectionStateObs => _connectionState;
  Rx<Map<String, dynamic>> get lastConnectedDeviceInfoObs => _lastConnectedDeviceInfo;
  
  /// 初始化蓝牙服务
  Future<BluetoothService> init() async {
    try {
      // 不在初始化时检查权限，改为在需要时才检查
      // await _checkAndRequestPermissions();
      
      // 在后台线程初始化蓝牙状态监听，避免主线程阻塞
      Future.microtask(() {
        // 监听蓝牙状态
        _stateSubscription = FlutterBluePlus.adapterState.listen((state) {
          _isOn.value = state == BluetoothAdapterState.on;
          _isAvailable.value = state != BluetoothAdapterState.unavailable;
          
          if (state == BluetoothAdapterState.on) {
            // 蓝牙打开时，获取已连接设备，但不请求权限
            // 只有在用户主动扫描时才请求权限
            // 在后台线程执行，避免主线程阻塞
            Future.microtask(() => _getConnectedDevices());
          } else if (state == BluetoothAdapterState.off) {
            // 蓝牙关闭时，清空设备列表
            _connectedDevices.clear();
            _scanResults.clear();
            _selectedDevice.value = null;
            _lastConnectedDeviceInfo.value = {};
          }
        });
      });
      
      // 不在初始化时立即检查蓝牙状态，而是延迟到UI渲染完成后
      // 这样可以避免启动时卡顿
      Future.delayed(const Duration(milliseconds: 800), () async {
        try {
          // 使用超时机制，避免无限等待蓝牙
          bool isOn = await FlutterBluePlus.isOn
              .timeout(const Duration(seconds: 3), onTimeout: () {
            Logger.error('检查蓝牙状态超时');
            return false;
          });
          
          _isOn.value = isOn;
          _isAvailable.value = isOn;
          
          if (isOn) {
            // 在后台线程获取设备，避免主线程阻塞
            Future.microtask(() => _getConnectedDevices());
          }
        } catch (e) {
          Logger.error('延迟检查蓝牙状态失败: $e');
        }
      });
      
      return this;
    } catch (e) {
      Logger.error('初始化蓝牙服务失败: $e');
      return this;
    }
  }
  
  /// 检查并请求蓝牙所需权限
  Future<bool> _checkAndRequestPermissions() async {
    // 暂时跳过权限检查，直接返回true
    _permissionsGranted.value = true;
    return true;
  }
  
  /// 再次请求权限
  Future<bool> requestPermissions() async {
    // 暂时跳过权限检查，直接返回true
    _permissionsGranted.value = true;
    return true;
  }
  
  /// 获取已连接的设备
  Future<void> _getConnectedDevices() async {
    try {
      // 使用超时机制，避免无限等待
      List<BluetoothDevice> devices = await FlutterBluePlus.connectedSystemDevices
          .timeout(const Duration(seconds: 3), onTimeout: () {
        Logger.error('获取已连接设备超时');
        return <BluetoothDevice>[];
      });
      
      _connectedDevices.value = devices;
      
      // 如果有已连接的设备但没有选中设备，则选中第一个
      if (_connectedDevices.isNotEmpty && _selectedDevice.value == null) {
        _selectedDevice.value = _connectedDevices[0];
        _monitorConnectionState(_selectedDevice.value!);
        // 更新最后连接的设备信息
        _updateLastConnectedDeviceInfo();
      }
      
      Logger.info('已连接设备数量: ${_connectedDevices.length}');
    } catch (e) {
      Logger.error('获取已连接设备失败: $e');
    }
  }
  
  /// 获取系统中已配对的设备
  Future<List<BluetoothDevice>> getPairedDevices() async {
    try {
      // 获取已配对的设备（系统已知设备）
      List<BluetoothDevice> systemDevices = await FlutterBluePlus.bondedDevices;
      return systemDevices;
    } catch (e) {
      Logger.error('获取已配对设备失败: $e');
      return [];
    }
  }
  
  /// 开始扫描附近的蓝牙设备并尝试连接最强信号设备
  Future<BluetoothDevice?> scanAndConnectToDevice({Duration? timeout}) async {
    if (_isScanning.value) {
      await stopScan();
    }
    
    // 清空旧的扫描结果
    _scanResults.clear();
    
    try {
      // 设置扫描监听
      _scanSubscription?.cancel();
      _scanSubscription = FlutterBluePlus.scanResults.listen((results) {
        _scanResults.value = results;
      });
      
      // 设置扫描中状态
      _isScanning.value = true;
      
      // 开始扫描
      await FlutterBluePlus.startScan(
        timeout: timeout ?? const Duration(seconds: 5),
      );
      
      // 扫描完成
      _isScanning.value = false;
      Logger.info('蓝牙扫描完成，发现 ${_scanResults.length} 个设备');
      
      // 如果找到设备，尝试连接信号最强的
      if (_scanResults.isNotEmpty) {
        // 按信号强度排序
        List<ScanResult> sortedResults = List.from(_scanResults);
        sortedResults.sort((a, b) => b.rssi.compareTo(a.rssi));
        
        // 尝试连接信号最强的设备
        final topDevice = sortedResults.first.device;
        Logger.info('尝试连接信号最强的设备: ${topDevice.platformName}');
        bool success = await connectToDevice(topDevice);
        
        if (success) {
          return topDevice;
        }
      }
      
      return null;
    } catch (e) {
      _isScanning.value = false;
      Logger.error('蓝牙扫描或连接失败: $e');
      return null;
    }
  }
  
  /// 停止扫描
  Future<void> stopScan() async {
    if (!_isScanning.value) return;
    
    try {
      await FlutterBluePlus.stopScan();
      _isScanning.value = false;
    } catch (e) {
      Logger.error('停止蓝牙扫描失败: $e');
    }
  }
  
  /// 连接到指定的蓝牙设备 - 简化版本
  Future<bool> connectToDevice(BluetoothDevice device) async {
    Logger.info('尝试连接设备: ${device.platformName} (${device.remoteId.str})');
    
    try {
      // 如果是当前已连接设备，直接返回成功
      if (_selectedDevice.value == device && 
          _connectionState.value == BluetoothConnectionState.connected) {
        Logger.info('设备已连接，无需重新连接');
        return true;
      }
      
      // 断开当前连接
      if (_selectedDevice.value != null && _selectedDevice.value != device) {
        await disconnectFromDevice();
      }
      
      // 直接尝试连接
      Logger.info('直接连接设备 ${device.platformName}');
      await device.connect();
      
      // 更新设备信息
      _selectedDevice.value = device;
      _monitorConnectionState(device);
      _updateLastConnectedDeviceInfo();
      
      Logger.info('设备 ${device.platformName} 连接成功');
      return true;
    } catch (e) {
      Logger.error('连接设备 ${device.platformName} 失败: $e');
      return false;
    }
  }
  
  /// 断开与当前设备的连接
  Future<bool> disconnectFromDevice() async {
    if (_selectedDevice.value == null) {
      Logger.info('没有当前选中的设备，无需断开连接');
      return true;
    }
    
    try {
      Logger.info('正在断开设备 ${_selectedDevice.value!.platformName} 的连接');
      await _selectedDevice.value!.disconnect();
      Logger.info('设备连接已断开，取消连接状态监听');
      _connectionSubscription?.cancel();
      _connectionSubscription = null;
      _selectedDevice.value = null;
      // 清除最后连接的设备信息
      _lastConnectedDeviceInfo.value = {};
      
      return true;
    } catch (e) {
      Logger.error('断开蓝牙设备连接失败: $e');
      return false;
    }
  }
  
  /// 监控连接状态
  void _monitorConnectionState(BluetoothDevice device) {
    Logger.info('设置设备 ${device.platformName} 的连接状态监听');
    // 取消之前的监听
    if (_connectionSubscription != null) {
      Logger.info('取消之前的连接状态监听');
      _connectionSubscription!.cancel();
      _connectionSubscription = null;
    }
    
    // 设置新的监听
    _connectionSubscription = device.connectionState.listen((state) {
      Logger.info('设备 ${device.platformName} 连接状态变更为: $state');
      _connectionState.value = state;
      
      if (state == BluetoothConnectionState.disconnected) {
        Logger.info('设备 ${device.platformName} 已断开连接');
        _selectedDevice.value = null;
        // 设备断开连接时，不清除最后连接的设备信息，以便下次可以重新连接
      } else if (state == BluetoothConnectionState.connected) {
        Logger.info('设备 ${device.platformName} 已成功连接');
        // 设备连接成功时，更新最后连接的设备信息
        _updateLastConnectedDeviceInfo();
      } else if (state == BluetoothConnectionState.connecting) {
        Logger.info('设备 ${device.platformName} 正在连接中...');
      } else if (state == BluetoothConnectionState.disconnecting) {
        Logger.info('设备 ${device.platformName} 正在断开连接...');
      }
    });
    
    Logger.info('设备 ${device.platformName} 的连接状态监听已设置');
  }
  
  /// 获取已连接设备的信息
  Map<String, dynamic> getConnectedDeviceInfo() {
    if (_selectedDevice.value == null) {
      return {
        'connected': false,
        'device': null,
      };
    }
    
    final deviceInfo = {
      'connected': _connectionState.value == BluetoothConnectionState.connected,
      'device': {
        'name': _selectedDevice.value!.platformName.isEmpty ? 
                '未命名设备' : _selectedDevice.value!.platformName,
        'id': _selectedDevice.value!.remoteId.str,
        'isConnected': _connectionState.value == BluetoothConnectionState.connected,
        'rssi': _scanResults
            .firstWhereOrNull((r) => r.device.remoteId == _selectedDevice.value!.remoteId)
            ?.rssi
      }
    };
    
    // 更新最后连接的设备信息
    _lastConnectedDeviceInfo.value = deviceInfo;
    
    return deviceInfo;
  }
  
  /// 更新最后连接的设备信息
  void _updateLastConnectedDeviceInfo() {
    if (_selectedDevice.value != null) {
      _lastConnectedDeviceInfo.value = {
        'connected': _connectionState.value == BluetoothConnectionState.connected,
        'device': {
          'name': _selectedDevice.value!.platformName.isEmpty ? 
                  '未命名设备' : _selectedDevice.value!.platformName,
          'id': _selectedDevice.value!.remoteId.str,
          'isConnected': _connectionState.value == BluetoothConnectionState.connected,
          'rssi': _scanResults
              .firstWhereOrNull((r) => r.device.remoteId == _selectedDevice.value!.remoteId)
              ?.rssi
        }
      };
    }
  }
  
  /// 一个综合方法，执行自动查找并连接设备的完整流程
  Future<BluetoothDevice?> autoConnectDevice() async {
    try {
      // 1. 先检查当前已连接设备
      if (_selectedDevice.value != null && 
          _connectionState.value == BluetoothConnectionState.connected) {
        Logger.info('使用当前已连接设备: ${_selectedDevice.value!.platformName}');
        return _selectedDevice.value;
      }
      
      // 2. 检查系统中已连接的设备
      try {
        List<BluetoothDevice> connectedDevices = await FlutterBluePlus.connectedSystemDevices
            .timeout(const Duration(seconds: 3));
        
        if (connectedDevices.isNotEmpty) {
          // 有已连接的设备，直接使用第一个
          Logger.info('发现系统已连接设备: ${connectedDevices.first.platformName}');
          
          // 连接设备并更新服务状态
          await connectToDevice(connectedDevices.first);
          return connectedDevices.first;
        }
      } catch (e) {
        Logger.error('检查系统连接设备失败: $e');
      }
      
      // 3. 尝试连接之前用过的设备(从已配对设备中寻找)
      List<BluetoothDevice> pairedDevices = await FlutterBluePlus.bondedDevices;
      
      // 如果有配对设备，尝试连接第一个
      if (pairedDevices.isNotEmpty) {
        Logger.info('尝试连接已配对设备: ${pairedDevices.first.platformName}');
        bool success = await connectToDevice(pairedDevices.first);
        if (success) {
          return pairedDevices.first;
        }
      }
      
      // 4. 没有找到可用设备
      return null;
    } catch (e) {
      Logger.error('自动连接设备流程失败: $e');
      return null;
    }
  }
  
  /// 获取设备连接状态的简化方法 (用于兼容现有代码)
  Future<BluetoothConnectionState> getReliableConnectionState(BluetoothDevice device) async {
    try {
      // 直接获取设备当前状态
      BluetoothConnectionState state = await device.connectionState.first
          .timeout(const Duration(seconds: 2), onTimeout: () {
        Logger.info('获取设备 ${device.platformName} 连接状态超时');
        return BluetoothConnectionState.disconnected;
      });
      
      // 如果获取到的状态是已连接，直接返回
      if (state == BluetoothConnectionState.connected) {
        return BluetoothConnectionState.connected;
      }
      
      // 作为备用检查，看设备是否在系统已连接列表中
      try {
        List<BluetoothDevice> connectedDevices = await FlutterBluePlus.connectedSystemDevices
            .timeout(const Duration(seconds: 2));
        
        for (var connectedDevice in connectedDevices) {
          if (connectedDevice.remoteId.str == device.remoteId.str) {
            return BluetoothConnectionState.connected;
          }
        }
      } catch (e) {
        // 忽略检查系统设备列表的错误
      }
      
      return state;
    } catch (e) {
      Logger.error('获取设备 ${device.platformName} 连接状态失败: $e');
      return BluetoothConnectionState.disconnected;
    }
  }
  
  @override
  void onClose() {
    _stateSubscription?.cancel();
    _scanSubscription?.cancel();
    _connectionSubscription?.cancel();
    disconnectFromDevice();
    super.onClose();
  }
}