using System;
using System.Linq;
using System.Text;
using System.Text.Json;
using System.Threading;
using System.Threading.Tasks;
using Infrastructure.Extensions;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using MQTTnet;
using MQTTnet.Client;
using MQTTnet.Protocol;
using ZR.Common.MqttHelper;
using ZR.Model.dc;
using ZR.Model.Dto;
using ZR.Model.mes.md;

namespace ZR.Service.mqtt
{
    public class MqttService : BaseService<DeviceUploadData>, IHostedService, IDisposable
    {
        private readonly ILogger<MqttService> _logger;
        private readonly IConfiguration _configuration;
        private readonly IMqttClient _mqttClient;
        private readonly MyMqttConfig _mqttConfig; // 注入配置类
        private readonly SemaphoreSlim _connectionLock = new SemaphoreSlim(1, 1);
        private readonly CancellationTokenSource _disposeCts = new CancellationTokenSource();
        private Timer _reconnectTimer;
        private bool _disposed = false;
        private int _reconnectAttempts = 0;

        // 配置常量
        private const string MqttConfigSection = "MqttConfig";
        private const string TopicsConfigKey = "Topics";
        private const int DefaultReconnectDelaySeconds = 5;
        private const int MaxReconnectAttempts = 10;
        private const int MaxReconnectDelaySeconds = 60;

        public MqttService(
            ILogger<MqttService> logger,
            IConfiguration configuration,
            MyMqttConfig mqttConfig
        )
        {
            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
            _configuration =
                configuration ?? throw new ArgumentNullException(nameof(configuration));
            _mqttConfig = mqttConfig ?? throw new ArgumentNullException(nameof(mqttConfig)); // 注入配置类
            // 创建MQTT客户端
            var factory = new MqttFactory();
            _mqttClient = factory.CreateMqttClient();

            // 注册事件处理程序
            _mqttClient.ConnectedAsync += OnConnectedAsync;
            _mqttClient.DisconnectedAsync += OnDisconnectedAsync;
            _mqttClient.ApplicationMessageReceivedAsync += OnMessageReceivedAsync;
            _logger.LogInformation($"MqttService 实例已创建，哈希值: {GetHashCode()}");
        }

        public async Task StartAsync(CancellationToken cancellationToken)
        {
            _logger.LogInformation("MQTT服务正在启动...");

            try
            {
                await ConnectAsync(cancellationToken);
                _logger.LogInformation("MQTT服务已成功启动");
            }
            catch (Exception ex)
            {
                _logger.LogCritical(ex, "MQTT服务启动失败，将在后台尝试重连");
                ScheduleReconnect(); // 即使启动失败，也应该尝试重连
            }
        }

        public async Task StopAsync(CancellationToken cancellationToken)
        {
            _logger.LogInformation("MQTT服务正在停止...");

            // 取消所有计划的重连
            _disposeCts.Cancel();
            _reconnectTimer?.Dispose();

            await DisconnectAsync(cancellationToken);
            _logger.LogInformation("MQTT服务已停止");
        }

        private async Task ConnectAsync(CancellationToken cancellationToken)
        {
            await _connectionLock.WaitAsync(cancellationToken);
            try
            {
                if (_mqttClient.IsConnected)
                {
                    _logger.LogDebug("MQTT客户端已连接，跳过连接操作");
                    return;
                }
                // 直接使用MyMqttConfig获取客户端选项
                var options = _mqttConfig.BuildMqttClientOptions();
                _logger.LogInformation($"正在连接到MQTT代理服务器 {options.ChannelOptions}...");
                try
                {
                    await _mqttClient.ConnectAsync(options, cancellationToken);
                    _reconnectAttempts = 0; // 重置重连计数
                    _logger.LogInformation("已成功连接到MQTT代理服务器");
                }
                catch (OperationCanceledException)
                {
                    _logger.LogWarning("MQTT连接操作被取消");
                    throw;
                }
                catch (Exception ex)
                {
                    _reconnectAttempts++;
                    _logger.LogError(
                        ex,
                        $"连接MQTT代理服务器失败 (尝试次数: {_reconnectAttempts}/{MaxReconnectAttempts})"
                    );

                    if (_reconnectAttempts >= MaxReconnectAttempts)
                    {
                        _logger.LogCritical("达到最大重连次数，停止尝试");
                        return;
                    }

                    ScheduleReconnect();
                    throw;
                }
            }
            finally
            {
                _connectionLock.Release();
            }
        }

        private MqttClientOptions BuildMqttClientOptions(IConfigurationSection config)
        {
            var builder = new MqttClientOptionsBuilder()
                .WithClientId(config["ClientId"] ?? Guid.NewGuid().ToString())
                .WithTcpServer(config["Server"], config.GetValue<int>("Port", 1883))
                .WithCleanSession();
            return builder.Build();
        }

        private async Task DisconnectAsync(CancellationToken cancellationToken)
        {
            if (!_mqttClient.IsConnected)
            {
                _logger.LogDebug("MQTT客户端未连接，跳过断开操作");
                return;
            }

            try
            {
                await _mqttClient.DisconnectAsync(cancellationToken: cancellationToken);
                _logger.LogInformation("已成功断开与MQTT代理服务器的连接");
            }
            catch (OperationCanceledException)
            {
                _logger.LogWarning("MQTT断开操作被取消");
                throw;
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "断开MQTT连接时出错");
                // 即使断开连接失败，也应该释放资源
                CleanupClientResources();
            }
        }

        private async Task OnConnectedAsync(MqttClientConnectedEventArgs e)
        {
            _logger.LogInformation($"MQTT连接已建立，会话是否存在: {e.ConnectResult.IsSessionPresent}");

            // 无论会话是否存在，都检查并确保订阅配置的主题
            // 这解决了配置文件修改后重启服务不订阅新主题的问题
            await SubscribeToTopicsAsync();
        }

        private async Task OnDisconnectedAsync(MqttClientDisconnectedEventArgs e)
        {
            _logger.LogWarning($"MQTT连接已断开 - 客户端是否之前已连接: {e.ClientWasConnected}");

            if (_disposed || _disposeCts.IsCancellationRequested)
            {
                _logger.LogDebug("MQTT断开连接是预期行为，正在关闭服务");
                return;
            }

            if (e.ClientWasConnected)
            {
                ScheduleReconnect();
            }
        }

        private async Task OnMessageReceivedAsync(MqttApplicationMessageReceivedEventArgs e)
        {
            try
            {
                var payload = Encoding.UTF8.GetString(e.ApplicationMessage.PayloadSegment);
                /*_logger.LogInformation(
                    $"收到MQTT消息 - 主题: {e.ApplicationMessage.Topic}, QoS: {e.ApplicationMessage.QualityOfServiceLevel}"
                );*/

                // 消息处理委托给专用的处理器
                await ProcessMessageAsync(e.ApplicationMessage.Topic, payload);
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "处理MQTT消息时出错");
            }
        }

        private async Task ProcessMessageAsync(string topic, string payload)
        {
            try
            {
                // 这里可以根据主题路由消息到不同的处理程序
                switch (topic)
                {
                    case string t when t.StartsWith("shgx_tz/device/"):
                        await HandleDeviceMessage(topic, payload);
                        break;
                    case "system/alert":
                        await HandleSystemAlert(payload);
                        break;
                    default:
                        _logger.LogDebug($"未处理的MQTT主题: {topic}");
                        break;
                }
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, $"处理主题 '{topic}' 的消息时出错");
            }
        }

        private readonly HashSet<string> _subscribedTopics = new HashSet<string>(); // 线程安全可加锁

        private async Task SubscribeToTopicsAsync()
        {
            if (!_mqttClient.IsConnected)
            {
                _logger.LogWarning("无法订阅：客户端未连接");
                return;
            }

            var subscribeOptions = _mqttConfig.GetSubscribeToTopicsAsync();
            if (subscribeOptions == null || !subscribeOptions.TopicFilters.Any())
            {
                _logger.LogInformation("无订阅主题配置");
                return;
            }

            // 提取需要订阅的主题
            var topicsToSubscribe = subscribeOptions.TopicFilters.Select(f => f.Topic).ToList();
            var topicFilters = subscribeOptions.TopicFilters.ToList();

            // 获取当前已订阅的主题
            HashSet<string> currentlySubscribedTopics;
            lock (_subscribedTopics)
            {
                currentlySubscribedTopics = new HashSet<string>(_subscribedTopics);
            }

            // 检查是否有新的主题需要订阅
            var newTopics = topicsToSubscribe.Except(currentlySubscribedTopics).ToList();
            var removedTopics = currentlySubscribedTopics.Except(topicsToSubscribe).ToList();

            if (!newTopics.Any() && !removedTopics.Any())
            {
                _logger.LogInformation("所有主题已正确订阅，无需变更");
                return;
            }

            // 处理新增的主题
            if (newTopics.Any())
            {
                var newTopicFilters = topicFilters.Where(f => newTopics.Contains(f.Topic)).ToList();
                if (newTopicFilters.Any())
                {
                    var newSubscribeOptionsBuilder = new MqttClientSubscribeOptionsBuilder();

                    foreach (var topicFilter in newTopicFilters)
                    {
                        newSubscribeOptionsBuilder.WithTopicFilter(topicFilter);
                    }

                    var newSubscribeOptions = newSubscribeOptionsBuilder.Build();

                    _logger.LogInformation($"订阅新主题: {string.Join(", ", newTopics)}");
                    var result = await _mqttClient.SubscribeAsync(newSubscribeOptions);

                    foreach (var item in result.Items)
                    {
                        _logger.LogInformation(
                            $"订阅结果：{item.TopicFilter.Topic} -> {item.ResultCode}"
                        );
                    }
                }
            }

            // 处理移除的主题（可选，根据业务需求决定是否取消订阅）
            if (removedTopics.Any())
            {
                _logger.LogInformation($"配置中移除的主题: {string.Join(", ", removedTopics)}");
                // 注意：这里没有执行取消订阅操作，因为有些场景下可能希望保留历史订阅
                // 如果需要取消订阅，请取消注释下面的代码

                // 使用构建器模式创建取消订阅选项
                var unsubscribeOptionsBuilder = new MqttClientUnsubscribeOptionsBuilder();

                // 为每个要取消订阅的主题调用WithTopic方法
                foreach (var topic in removedTopics)
                {
                    unsubscribeOptionsBuilder.WithTopicFilter(topic);
                }

                var unsubscribeOptions = unsubscribeOptionsBuilder.Build();
                await _mqttClient.UnsubscribeAsync(unsubscribeOptions);
                _logger.LogInformation($"已取消订阅: {string.Join(", ", removedTopics)}");
            }

            // 更新本地已订阅主题列表
            lock (_subscribedTopics)
            {
                _subscribedTopics.Clear();
                _subscribedTopics.UnionWith(topicsToSubscribe);
            }
        }

        private void ScheduleReconnect()
        {
            // 实现指数退避算法
            var delaySeconds = Math.Min(
                DefaultReconnectDelaySeconds * (int)Math.Pow(2, Math.Min(_reconnectAttempts, 5)),
                MaxReconnectDelaySeconds
            );

            _logger.LogInformation($"计划在 {delaySeconds} 秒后尝试重新连接MQTT代理服务器");

            // 使用Timer替代Task.Run，更好地控制资源
            _reconnectTimer?.Dispose();
            _reconnectTimer = new Timer(
                async _ =>
                {
                    if (_disposed || _disposeCts.IsCancellationRequested)
                    {
                        _logger.LogDebug("跳过重连：服务正在关闭");
                        return;
                    }

                    try
                    {
                        await ConnectAsync(_disposeCts.Token);
                    }
                    catch (Exception ex)
                    {
                        _logger.LogError(ex, "计划的MQTT重连失败");
                    }
                },
                null,
                TimeSpan.FromSeconds(delaySeconds),
                Timeout.InfiniteTimeSpan
            );
        }

        private Task HandleDeviceMessage(string topic, string payload)
        {
            //_logger.LogInformation($"处理设备消息: {topic} - {payload}");
            // plc网关抓取数据上传
            if (topic.Contains("device/data/push"))
            {
                DeviceUploadDataGatWayDto deviceUploadDataGatWayDto =
                    JsonSerializer.Deserialize<DeviceUploadDataGatWayDto>(payload);
                // 这里添加设备消息处理逻辑
                string deviceCode = topic.Split("/")[2];

                DeviceUploadData lastDeviceUploadData = Context
                    .Queryable<DeviceUploadData>()
                    .Where(it => it.DeviceCode == deviceCode)
                    .OrderByDescending(it => it.UploadTime)
                    .First();
                DateTime lastTime =  lastDeviceUploadData.UploadTime;

                // 每一小时上传一下

                DeviceUploadData deviceUploadData =
                    new()
                    {
                        FactoryCode = "上海干巷",
                        WorkshopCode = "涂装车间",
                        LineCode = "涂装生产线",
                        DeviceCode = deviceCode,
                        DictCode = "device_dict_plc_001",
                        Remark = "网关采集设备数据",
                        UploadTime = DateTime.Now,
                        CollectionTime = DateTimeOffset
                            .FromUnixTimeMilliseconds(deviceUploadDataGatWayDto.Time)
                            .LocalDateTime,
                        Value01 = deviceUploadDataGatWayDto.DeviceParams.Value01.ToString(),
                        Value02 = deviceUploadDataGatWayDto.DeviceParams.Value02.ToString(),
                        Value03 = deviceUploadDataGatWayDto.DeviceParams.Value03.ToString(),
                        Value04 = deviceUploadDataGatWayDto.DeviceParams.Value04.ToString(),
                        Value05 = deviceUploadDataGatWayDto.DeviceParams.Value05.ToString(),
                        Value06 = deviceUploadDataGatWayDto.DeviceParams.Value06.ToString(),
                        Value07 = deviceUploadDataGatWayDto.DeviceParams.Value07.ToString(),
                        Value08 = deviceUploadDataGatWayDto.DeviceParams.Value08.ToString(),
                        Value09 = deviceUploadDataGatWayDto.DeviceParams.Value09.ToString(),
                        Value10 = deviceUploadDataGatWayDto.DeviceParams.Value10.ToString()
                    };
                Context.Insertable(deviceUploadData).ExecuteCommand();
            }

            return Task.CompletedTask;
        }

        private Task HandleSystemAlert(string payload)
        {
            _logger.LogWarning($"系统警报: {payload}");
            // 这里添加系统警报处理逻辑
            return Task.CompletedTask;
        }

        public async Task PublishAsync(
            string topic,
            string payload,
            MqttQualityOfServiceLevel qos = MqttQualityOfServiceLevel.AtLeastOnce,
            bool retain = false
        )
        {
            if (string.IsNullOrEmpty(topic))
            {
                throw new ArgumentNullException(nameof(topic), "MQTT主题不能为空");
            }

            if (payload == null)
            {
                throw new ArgumentNullException(nameof(payload), "MQTT消息内容不能为空");
            }

            await _connectionLock.WaitAsync(_disposeCts.Token);
            try
            {
                if (!_mqttClient.IsConnected)
                {
                    _logger.LogWarning("发布消息前需要连接MQTT代理服务器");
                    //await ConnectAsync(_disposeCts.Token);
                    throw new Exception("发布消息前需要连接MQTT代理服务器");
                }

                var message = new MqttApplicationMessageBuilder()
                    .WithTopic(topic)
                    .WithPayload(payload)
                    .WithQualityOfServiceLevel(qos)
                    .WithRetainFlag(retain)
                    .Build();

                _logger.LogDebug($"准备发布MQTT消息 - 主题: {topic}, QoS: {qos}, 保留: {retain}");

                try
                {
                    var result = await _mqttClient.PublishAsync(message, _disposeCts.Token);
                    _logger.LogInformation($"已发布MQTT消息 - 主题: {topic}, 结果: {result.ReasonCode}");
                }
                catch (OperationCanceledException)
                {
                    _logger.LogWarning("MQTT发布操作被取消");
                    throw;
                }
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, $"发布MQTT消息失败 - 主题: {topic}");
                throw;
            }
            finally
            {
                _connectionLock.Release();
            }
        }

        private void CleanupClientResources()
        {
            try
            {
                _mqttClient.ApplicationMessageReceivedAsync -= OnMessageReceivedAsync;
                _mqttClient.ConnectedAsync -= OnConnectedAsync;
                _mqttClient.DisconnectedAsync -= OnDisconnectedAsync;

                if (_mqttClient.IsConnected)
                {
                    _mqttClient.DisconnectAsync().GetAwaiter().GetResult();
                }

                _mqttClient.Dispose();
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "清理MQTT客户端资源时出错");
            }
        }

        public void Dispose()
        {
            Dispose(true);
            GC.SuppressFinalize(this);
        }

        protected virtual void Dispose(bool disposing)
        {
            if (!_disposed)
            {
                if (disposing)
                {
                    _disposeCts.Cancel();
                    _reconnectTimer?.Dispose();
                    _connectionLock.Dispose();
                    CleanupClientResources();
                    _disposeCts.Dispose();
                }

                _disposed = true;
                _logger.LogDebug("MQTT服务已释放所有资源");
            }
        }
    }
}