using System;
using global::System.Net;
using global::System.Net.Sockets;
using global::System.Threading;
using System.Threading.Tasks;

namespace Pilz.Networking
{
    public class UDPManager : ConnectionManagerBase
    {
        public UDPManager(int port) : base(port)
        {
            cancelToken = cancelTokenSource.Token;
            client = new UdpClient(port);
        }

        private readonly UdpClient client;
        private Task listenTask = null;
        private readonly CancellationTokenSource cancelTokenSource = new CancellationTokenSource();
        private readonly CancellationToken cancelToken;

        public int MaxBufferSize { get; private set; } = 8192;

        ~UDPManager()
        {
            client.Client.Shutdown(SocketShutdown.Both);
            client.Close();
        }

        public override void Start()
        {
            if (!IsListening)
            {
                StartInternal();
            }
        }

        private void StartInternal()
        {
            IsListening = true;
            listenTask = Task.Run(() => { try { RetriveAnyData(cancelToken); } catch (Exception ex) { IsListening = false; } });
        }

        public override void Stop()
        {
            if (IsListening)
            {
                IsListening = false;
                cancelTokenSource.Cancel();
                listenTask.Wait();
            }
        }

        protected override int GetBufferSize()
        {
            return MaxBufferSize;
        }

        private void RetriveAnyData(CancellationToken ct)
        {
            void doExit() => ct.ThrowIfCancellationRequested();
            var receiveTask = client.ReceiveAsync();

            // Wait for the data and cancel if requested
            receiveTask.Wait(ct);
            var buf = receiveTask.Result.Buffer;
            string ip = receiveTask.Result.RemoteEndPoint.Address.ToString();
            doExit();
            ProcessRetrivedData(ip, buf);
            doExit();
            StartInternal();
        }

        protected override void SendData(IPEndPoint ep, byte[] buf)
        {
            var udp = new UdpClient();
            udp.Connect(ep);
            udp.Send(buf, buf.Length);
            udp.Client.Shutdown(SocketShutdown.Both);
            udp.Close();
        }
    }
}