public class NetAsyncMgr : MonoBehaviour
{
    private static NetAsyncMgr instance;
    public static NetAsyncMgr Instance => instance;
    //和服务器进行链接的Socket
    private Socket socket;
    //接收消息的用的 缓存容器
    private byte[] cacheByte = new byte[1024*1024];
    private int cacheNum = 0;
    
    // Start is called before the first frame update
    void Awake()
    {
        instance = this;
        //过场景不移除
        DontDestroyOnLoad(this.gameObject);
    }

    // Update is called once per frame
    void Update()
    {
        
    }
    //链接服务器
    public void Connect(string ip, int port)
    {
        if(socket!=null&&socket.Connected)
            return;
        IPEndPoint ipPoint = new IPEndPoint(IPAddress.Parse(ip), port);
        socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
        SocketAsyncEventArgs args = new SocketAsyncEventArgs();
        args.RemoteEndPoint = ipPoint;
        args.Completed += (socket, args) =>
        {
            if (args.SocketError == SocketError.Success)
            {
                print("链接成功");
                //收消息
                SocketAsyncEventArgs receiveArgs = new SocketAsyncEventArgs();
                receiveArgs.SetBuffer(cacheByte, 0, cacheByte.Length);
                receiveArgs.Completed += ReceiveCallback;
                this.socket.ReceiveAsync(receiveArgs);
            }
            else
            {
                print("链接失败"+args.SocketError);
            }
        };
        socket.ConnectAsync(args);
        
        
    }
    //收消息完成的回调函数
    private void ReceiveCallback(object sender, SocketAsyncEventArgs args)
    {
        if (args.SocketError == SocketError.Success)
        {
            //解析消息 暂时用字符串规则
            print(Encoding.UTF8.GetString(args.Buffer, 0, args.BytesTransferred));
            //继续去接收消息
            args.SetBuffer(cacheByte, 0, cacheByte.Length);
            //继续异步接收消息
            if (socket!=null && this.socket.Connected) 
                socket.ReceiveAsync(args);
            else
                Close();
            
        }
        else
        {
            print("接收消息出错"+args.SocketError);
            //关闭客户端链接
            Close();
        }
    }
    public void Close()
    {
        if (socket != null)
        {
            socket.Shutdown(SocketShutdown.Both);
            socket.Disconnect(false);
            socket.Close();
            socket = null;
        }
    }

    public void Send(string str)
    {
        if (socket != null && this.socket.Connected)
        {
            byte[] bytes = Encoding.UTF8.GetBytes(str);
            SocketAsyncEventArgs args = new SocketAsyncEventArgs();
            args.SetBuffer(bytes, 0, bytes.Length);
            args.Completed += (socket, args) =>
            {
                if (args.SocketError != SocketError.Success)
                {
                    print("发送消息失败"+args.SocketError);
                    Close();
                }
            };
            this.socket.SendAsync(args);
        }
        else
        {
            Close();
        }
    }
}