using MQTTnet;
using MQTTnet.Client;
using MQTTnet.Formatter;
using MQTTnet.Protocol;
using System;
using System.Collections.Concurrent;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace linesider_screen_tool
{
    public class MQTTHepler 
    {
        public IMqttClient _mqttClient;
        private MqttClientOptions _options;
        private readonly string _clientId;
        private readonly string _server;
        private readonly int _port;
        private readonly string _username;
        private readonly string _password;
        private readonly bool _cleanSession;

        
        /// <summary>
        /// 初始化 MQTT 客户端
        /// </summary>
        public MQTTHepler(string server, int port = 1883, string clientId = null,
                         string username = null, string password = null, bool cleanSession = true)
        {
            _server = server;
            _port = port;
            _clientId = clientId;
            _username = username;
            _password = password;
            _cleanSession = cleanSession;
        }

        /// <summary>
        /// 连接到 MQTT 服务器
        /// </summary>
        public async Task ConnectAsync()
        {
            if (_mqttClient != null && _mqttClient.IsConnected)
                return;

            var factory = new MqttFactory();
            _mqttClient = factory.CreateMqttClient();

            // 先注册事件处理器
            //_mqttClient.ApplicationMessageReceivedAsync += HandleReceivedApplicationMessage;

            var builder = new MqttClientOptionsBuilder()
                .WithTcpServer(_server, _port)
                .WithClientId(_clientId) // 确保指定了 ClientId
                .WithCleanSession(_cleanSession);

            if (!string.IsNullOrEmpty(_username))
                builder.WithCredentials(_username, _password);

            _options = builder.Build();

            _mqttClient.DisconnectedAsync += async e =>
            {
                Console.WriteLine($"MQTT 断开: {e.Reason}");
                await Task.Delay(5000);
                await ReconnectAsync();
            };

            await _mqttClient.ConnectAsync(_options, CancellationToken.None);
            Console.WriteLine("MQTT 连接成功");
        }

        /// <summary>
        /// 订阅主题
        /// </summary>
        public async Task SubscribeAsync(string topic, MqttQualityOfServiceLevel qos = MqttQualityOfServiceLevel.AtLeastOnce)
        {
            if (_mqttClient == null || !_mqttClient.IsConnected)
                await ConnectAsync();

            var topicFilter = new MqttTopicFilterBuilder()
                .WithTopic(topic)
                .WithQualityOfServiceLevel(qos)
                .Build();

            var result = await _mqttClient.SubscribeAsync(topicFilter, CancellationToken.None);
            Console.WriteLine($"订阅结果: {result.Items.First().ResultCode}");
        }

        /// <summary>
        /// 发布消息
        /// </summary>
        public async Task PublishAsync(string topic, string payload,MqttQualityOfServiceLevel qos = MqttQualityOfServiceLevel.AtLeastOnce,
        bool retain = false)
        {
            if (_mqttClient == null || !_mqttClient.IsConnected)
                await ConnectAsync();

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

            try
            {
                await _mqttClient.PublishAsync(message, CancellationToken.None);
                Console.WriteLine($"已发布消息到主题 {topic}: {payload}");
            }
            catch (Exception ex)
            {
                Console.WriteLine($"发布消息失败: {ex.Message}");
                throw;
            }
        }

        /// <summary>
        /// 取消订阅主题
        /// </summary>
        public async Task UnsubscribeAsync(string topic)
        {
            if (_mqttClient == null || !_mqttClient.IsConnected)
                return;

            try
            {
                await _mqttClient.UnsubscribeAsync(topic, CancellationToken.None);
                Console.WriteLine($"已取消订阅主题: {topic}");
            }
            catch (Exception ex)
            {
                Console.WriteLine($"取消订阅主题失败: {ex.Message}");
                throw;
            }
        }

        private async Task ReconnectAsync()
        {
            try
            {
                await _mqttClient.ConnectAsync(_options, CancellationToken.None);
                Console.WriteLine("MQTT 重新连接成功");
            }
            catch (Exception ex)
            {
                Console.WriteLine($"MQTT 重新连接失败: {ex.Message}");
            }
        }

        public async Task DisconnectAsync()
        {
            if (_mqttClient == null || !_mqttClient.IsConnected)
                return;

            try
            {
                await _mqttClient.DisconnectAsync();
                DisconnectAsync().Wait();
                _mqttClient?.Dispose();
                GC.SuppressFinalize(this);
                Console.WriteLine("MQTT 已断开连接");
            }
            catch (Exception ex)
            {
                Console.WriteLine($"断开连接失败: {ex.Message}");
            }
        }
    }
}