using Microsoft.VisualBasic;
using MQTTnet;
using MQTTnet.Protocol;
using NLog;
using Proto;

namespace IotManager.services
{
    public class MqttClientHostedService : BackgroundService
    {
        public static IMqttClient? _mqttClient;
        public MqttClientOptions? _options;
        public static bool IsConnectioned { get; set; }

        public IConfiguration? Configuration { get; set; }

        private static Logger _logger = LogManager.GetCurrentClassLogger();

        // 重连相关变量
        private readonly SemaphoreSlim _reconnectLock = new(1, 1);
        private bool _isReconnecting = false;
        private int _reconnectAttempts = 0;
        private const int MAX_RECONNECT_ATTEMPTS = 10;
        private const int RECONNECT_DELAY_SECONDS = 5;

        public MqttClientHostedService(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        protected override async Task ExecuteAsync(CancellationToken stoppingToken)
        {
            await InitializeMqttClient();

            // 主循环，持续监控连接状态
            while (!stoppingToken.IsCancellationRequested)
            {
                try
                {
                    if (!IsConnectioned && !_isReconnecting)
                    {
                        await ReconnectWithRetry();
                    }

                    // 每30秒检查一次连接状态
                    await Task.Delay(TimeSpan.FromSeconds(30), stoppingToken);
                }
                catch (OperationCanceledException)
                {
                    // 服务停止
                    break;
                }
                catch (Exception ex)
                {
                    _logger.Error($"MQTT监控循环异常: {ex.Message}");
                    await Task.Delay(TimeSpan.FromSeconds(10), stoppingToken);
                }
            }

            // 清理资源
            await DisposeAsync();
        }

        private async Task InitializeMqttClient()
        {
            try
            {
                var factory = new MQTTnet.MqttClientFactory();
                _mqttClient = factory.CreateMqttClient();


                var IP = Configuration["MQTT:IP"];
                int Port = 1883;
                int.TryParse(Configuration["MQTT:Port"], out Port);
                var UserName = Configuration["MQTT:UserName"];
                var PWD = Configuration["MQTT:PassWord"];
                string clientId = "IOTConsumer#" + Guid.NewGuid().ToString("N");

                _options = new MqttClientOptionsBuilder()
                    .WithTcpServer(IP, Port)
                    .WithClientId(clientId)
                    .WithCredentials(UserName, PWD)
                    .WithWillQualityOfServiceLevel(MqttQualityOfServiceLevel.AtMostOnce)
                    .WithProtocolVersion(MQTTnet.Formatter.MqttProtocolVersion.V500)
                    .Build();

                // 注册事件
                _mqttClient.ConnectedAsync += OnConnectedAsync;
                _mqttClient.DisconnectedAsync += OnDisconnectedAsync;
                _mqttClient.ApplicationMessageReceivedAsync += OnApplicationMessageReceivedAsync;

                await ConnectAsync();
            }
            catch (Exception ex)
            {
                _logger.Error($"MQTT初始化错误: {ex.Message}");
                _logger.Error(ex.StackTrace);
            }
        }

        private async Task ConnectAsync()
        {
            try
            {
                if (_mqttClient == null || _options == null)
                    return;

                _logger.Info("正在连接MQTT服务器...");
                await _mqttClient.ConnectAsync(_options);
            }
            catch (Exception ex)
            {
                _logger.Error($"MQTT连接失败: {ex.Message}");
                IsConnectioned = false;
            }
        }

        private async Task OnConnectedAsync(MqttClientConnectedEventArgs arg)
        {
            _logger.Info("MQTT连接成功");
            IsConnectioned = true;
            _reconnectAttempts = 0; // 重置重连计数

            // 重新订阅主题（如果需要）
            await ResubscribeTopics();

            await Task.CompletedTask;
        }

        private async Task OnDisconnectedAsync(MqttClientDisconnectedEventArgs e)
        {
            _logger.Warn($"MQTT连接断开，原因: {e.Reason}");
            IsConnectioned = false;

            // 如果不是正常断开，启动重连
            if (e.Reason != MqttClientDisconnectReason.NormalDisconnection)
            {
                await ReconnectWithRetry();
            }

            await Task.CompletedTask;
        }

        private async Task ReconnectWithRetry()
        {
            // 使用锁防止多个重连同时进行
            if (!await _reconnectLock.WaitAsync(0))
                return;

            try
            {
                if (_isReconnecting || IsConnectioned)
                    return;

                _isReconnecting = true;
                _reconnectAttempts++;

                _logger.Info($"尝试重连MQTT服务器 (第{_reconnectAttempts}次)...");

                // 指数退避策略：重连间隔逐渐增加
                int delaySeconds = Math.Min(RECONNECT_DELAY_SECONDS * _reconnectAttempts, 300); // 最大5分钟

                await Task.Delay(TimeSpan.FromSeconds(delaySeconds));

                await ConnectAsync();

                // 如果超过最大重连次数，重置计数器
                if (_reconnectAttempts >= MAX_RECONNECT_ATTEMPTS)
                {
                    _reconnectAttempts = 0;
                    _logger.Warn("已达到最大重连次数，将重新开始重连计数");
                }
            }
            catch (Exception ex)
            {
                _logger.Error($"重连失败: {ex.Message}");
            }
            finally
            {
                _isReconnecting = false;
                _reconnectLock.Release();
            }
        }

        private async Task ResubscribeTopics()
        {
            try
            {
                // 这里重新订阅您需要的主题
                // 例如：await SubscribeAsync("your/topic");
                _logger.Info("MQTT主题重新订阅完成");
            }
            catch (Exception ex)
            {
                _logger.Error($"重新订阅主题失败: {ex.Message}");
            }
        }

        private async Task OnApplicationMessageReceivedAsync(MqttApplicationMessageReceivedEventArgs arg)
        {
            try
            {
                var topic = arg.ApplicationMessage.Topic;
                var payload = arg.ApplicationMessage.ConvertPayloadToString();

                _logger.Debug($"收到MQTT消息 - 主题: {topic}, 负载: {payload}");

                // 处理消息的业务逻辑
                await ProcessMessage(topic, payload);
            }
            catch (Exception ex)
            {
                _logger.Error($"处理MQTT消息异常: {ex.Message}");
            }
        }

        private async Task ProcessMessage(string topic, string payload)
        {
            // 实现您的消息处理逻辑
            await Task.CompletedTask;
        }

        public async Task SubscribeAsync(string topic)
        {
            try
            {
                if (_mqttClient?.IsConnected == true)
                {
                    var subscribeOptions = new MqttClientSubscribeOptionsBuilder()
                        .WithTopicFilter(topic)
                        .Build();

                    await _mqttClient.SubscribeAsync(subscribeOptions);
                    _logger.Info($"成功订阅主题: {topic}");
                }
            }
            catch (Exception ex)
            {
                _logger.Error($"订阅主题失败 {topic}: {ex.Message}");
            }
        }

        public static async Task PublishAsync(string topic, string payload)
        {
            try
            {
                if (_mqttClient?.IsConnected == true)
                {
                    var message = new MqttApplicationMessageBuilder()
                        .WithTopic(topic)
                        .WithPayload(payload)
                        .WithQualityOfServiceLevel(MqttQualityOfServiceLevel.AtMostOnce)
                        .Build();

                    await _mqttClient.PublishAsync(message);
                    _logger.Debug($"MQTT消息发送成功 - 主题: {topic}");
                }
                else
                {
                    _logger.Warn("MQTT客户端未连接，消息发送失败");
                }
            }
            catch (Exception ex)
            {
                _logger.Error($"MQTT消息发送失败: {ex.Message}");
            }
        }

        public async ValueTask DisposeAsync()
        {
            try
            {
                if (_mqttClient != null)
                {
                    _mqttClient.ConnectedAsync -= OnConnectedAsync;
                    _mqttClient.DisconnectedAsync -= OnDisconnectedAsync;
                    _mqttClient.ApplicationMessageReceivedAsync -= OnApplicationMessageReceivedAsync;

                    if (_mqttClient.IsConnected)
                    {
                        await _mqttClient.DisconnectAsync();
                    }
                    _mqttClient.Dispose();
                }
                _logger.Info("MQTT客户端已释放");
            }
            catch (Exception ex)
            {
                _logger.Error($"释放MQTT客户端时出错: {ex.Message}");
            }
        }
    }
}