using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net;
using System.Threading.Tasks;
using System.Net.Sockets;

namespace HDLMonitorService.UDP
{
    public class UDPServer
    {
        private static Socket udpSocket;

        /// <summary>
        /// 启动Socket接收和发送功能
        /// </summary>
        /// <param name="port"></param>
        public static void Start()
        {
            if (IsRunning)
            {
                return;
            }
            udpSocket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
            udpSocket.Bind(new IPEndPoint(IPAddress.Any, 0));
            asyncBeginReceive();
        }

        public static void Close()
        {
            if (!IsRunning)
            {
                return;
            }
            udpSocket.Close();
            udpSocket = null;
            System.Threading.Thread.Sleep(100);
        }

        private static bool IsRunning
        {
            get
            {
                return null == udpSocket ? false : true;
            }
        }

        private static void asyncBeginReceive()
        {
            if (!IsRunning)
            {
                return;
            }

            try
            {
                var tempPacket = new Packet { };
                udpSocket.BeginReceiveFrom(tempPacket.Bytes, 0, tempPacket.Bytes.Length, SocketFlags.None, ref tempPacket.RemoteEndPoint, new AsyncCallback(asyncEndReceive), tempPacket);
            }
            catch
            {
                System.Threading.Thread.Sleep(1);
                asyncBeginReceive();
            }
        }

        private static void asyncEndReceive(IAsyncResult iar)
        {
            if (!IsRunning)
            {
                return;
            }

            try
            {
                var tempPacket = (Packet)iar.AsyncState;
                var len = udpSocket.EndReceiveFrom(iar, ref tempPacket.RemoteEndPoint);
                var bytes = new byte[len];
                System.Array.Copy(tempPacket.Bytes, 0, bytes, 0, bytes.Length);
                tempPacket.Bytes = bytes;
                asyncBeginReceive();
                tempPacket.Manager();
            }
            catch
            {
                asyncBeginReceive();
            }
        }

        public static void AsyncBeginSend(Packet tempPacket)
        {
            try
            {
                udpSocket.BeginSendTo(tempPacket.Bytes, 0, tempPacket.Bytes.Length, SocketFlags.None, tempPacket.RemoteEndPoint, new AsyncCallback(asyncEndSend), tempPacket);
            }
            catch { }
        }

        private static void asyncEndSend(IAsyncResult iar)
        {
            try
            {
                int bytesSent = udpSocket.EndSendTo(iar);
            }
            catch { }
        }
    }
}