using System;
using System.Net;
using System.Net.Sockets;
using System.Text;
using System.Threading;

namespace Infrastructure
{


    /// <summary>
    /// Socket 服务端工具类（你的“接受端”）
    /// 功能：监听端口，与网关（客户端）建立长连接，支持收发字节数据（byte[]）
    /// </summary>
    public class SocketGatewayServer : IDisposable
    {
        private TcpListener _listener;
        private bool _isRunning;
        private Thread _acceptThread;

        private TcpClient _connectedClient;
        private NetworkStream _clientStream;
        private bool _clientConnected;

        private readonly string _listenIp;
        private readonly int _listenPort;

        /// <summary>
        /// 构造函数
        /// </summary>
        /// <param name="listenIp">监听的IP，如 "127.0.0.1" 或 "0.0.0.0"</param>
        /// <param name="listenPort">监听的端口，如 8888</param>
        public SocketGatewayServer(string listenIp = "127.0.0.1", int listenPort = 8888)
        {
            _listenIp = listenIp;
            _listenPort = listenPort;
        }

        /// <summary>
        /// 启动服务端，开始监听网关（客户端）连接
        /// </summary>
        public void Start()
        {
            if (_isRunning) return;

            try
            {
                IPAddress ipAddress = string.IsNullOrEmpty(_listenIp) || _listenIp == "0.0.0.0"
                    ? IPAddress.Any
                    : IPAddress.Parse(_listenIp);

                _listener = new TcpListener(ipAddress, _listenPort);
                _listener.Start();
                _isRunning = true;

                Console.WriteLine($"Socket 服务端已启动，正在监听 [{_listenIp}]:{_listenPort}");

                _acceptThread = new Thread(AcceptClient);
                _acceptThread.IsBackground = true;
                _acceptThread.Start();
            }
            catch (Exception ex)
            {
                Console.WriteLine($"❌ 启动服务端失败: {ex.Message}");
                Stop();
            }
        }

        /// <summary>
        /// 等待并接受一个客户端（网关）连接
        /// </summary>
        private void AcceptClient()
        {
            try
            {
                while (_isRunning)
                {
                    Console.WriteLine(" 等待网关（客户端）连接...");

                    TcpClient client = _listener.AcceptTcpClient(); // 阻塞直到客户端连接
                    Console.WriteLine($"网关（客户端）已连接: {client.Client.RemoteEndPoint}");
                    StartReceiving();

                    lock (this)
                    {
                        // 断开之前的连接（如果存在）
                        _connectedClient?.Close();
                        _connectedClient = client;
                        _clientStream = client.GetStream();
                        _clientConnected = true;

                        Console.WriteLine("已建立长连接，可以开始收发字节数据");
                    }
                }
            }
            catch (Exception ex)
            {
                if (_isRunning)
                    Console.WriteLine($"接受客户端时出错: {ex.Message}");
            }
        }

        /// <summary>
        /// 向网关（客户端）发送字节数据（byte[]）
        /// </summary>
        /// <param name="data">要发送的字节数据</param>
        /// <returns>是否发送成功</returns>
        public bool SendToGateway(byte[] data)
        {
           if (!_clientConnected || _clientStream == null || _connectedClient == null)
            {
                Console.WriteLine(" 未连接到网关，无法发送数据");
                return false;
            }

            try
            {
                _clientStream.Write(data, 0, data.Length);
                Console.WriteLine($" 已发送 {data.Length} 字节数据给网关");
                return true;
            }
            catch (Exception ex)
            {
                Console.WriteLine($"发送数据失败: {ex.Message}");
                DisconnectClient();
                return false;
            }
        }

        /// <summary>
        /// （可选）接收来自网关的字节数据
        /// </summary>
        public void StartReceiving()
        {
            Thread receiveThread = new Thread(ReceiveLoop);
            receiveThread.IsBackground = true;
            receiveThread.Start();
        }

        private void ReceiveLoop()
        {
            byte[] buffer = new byte[4096]; // 可根据需求调整缓冲区大小

            try
            {
                while (_clientConnected && _connectedClient != null && _clientStream != null)
                {
                    if (_clientStream.DataAvailable)
                    {
                        int bytesRead = _clientStream.Read(buffer, 0, buffer.Length);
                        if (bytesRead > 0)
                        {
                            byte[] receivedData = new byte[bytesRead];
                            Buffer.BlockCopy(buffer, 0, receivedData, 0, bytesRead);

                            Console.WriteLine($"收到来自网关的 {bytesRead} 字节数据");

                            // 🔧 新增：将收到的 byte[] 使用 GBK 编码转换为字符串
                          //  string receivedText = Encoding.GetEncoding("GBK").GetString(receivedData);

                         //   Console.WriteLine($"GBK 解码后的报文内容: {receivedText}");
                            PrintBytesAsHex(receivedData);
                            // TODO: 你可以在这里进一步处理 receivedText 或 receivedData
                        }
                    }
                    else
                    {
                        Thread.Sleep(100); // 避免空转消耗 CPU
                    }
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine($"接收数据时出错: {ex.Message}");
            }
            finally
            {
                Console.WriteLine("接收线程已退出");
            }
        }
        /// <summary>
        /// 将字节数组转换为十六进制字符串并打印
        /// </summary>
        /// <param name="bytes">要转换的字节数组</param>
        static void PrintBytesAsHex(byte[] bytes)
        {
            if (bytes == null || bytes.Length == 0)
            {
                Console.WriteLine("字节数组为空或长度为0。");
                return;
            }

            // 使用 StringBuilder 或直接拼接，这里使用 String.Join 和格式化
            string hexString = BitConverter.ToString(bytes).Replace("-", " "); // 可选：用空格分隔每个字节
                                                                               // 或者不替换，就是用 "-" 分隔：string hexString = BitConverter.ToString(bytes);

            Console.WriteLine("字节数据的十六进制表示为："+ hexString);
         
        }

        private void DisconnectClient()
        {
            lock (this)
            {
                _clientConnected = false;
                _clientStream?.Close();
                _connectedClient?.Close();
                _clientStream = null;
                _connectedClient = null;
                Console.WriteLine("🔌 已断开与网关的连接");
            }
        }

        public void Stop()
        {
            _isRunning = false;
            DisconnectClient();
            _listener?.Stop();
            Console.WriteLine("🛑 Socket 服务端已停止");
        }

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


        /// <summary>
        /// 计算多个 byte[] 数组中所有字节之和，然后对 256 取余，返回校验字节（0~255）
        /// </summary>
        /// <param name="byteArrays">多个 byte[] 数组，可以是任意数量</param>
        /// <returns>校验和，一个字节（0~255），即：所有字节之和 % 256</returns>
        public static byte CalculateChecksum(params byte[][] byteArrays)
        {
            int sum = 0;

            // 遍历每一个 byte[] 数组
            foreach (byte[] bytes in byteArrays)
            {
                if (bytes == null)
                    continue; // 如果某个数组为空，跳过（你也可以选择抛异常）

                // 累加该数组中的每一个字节
                foreach (byte b in bytes)
                {
                    sum += b; // byte 自动提升为 int，安全累加
                }
            }

            // 计算校验和：总和 % 256，然后转为 byte（范围保证是 0~255）
            return (byte)(sum % 256);
        }
    }
}