using System;
using System.Collections;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Diagnostics;
using System.Net;
using System.Net.Sockets;
using System.Threading;
using LiteNetLib.Layers;
using LiteNetLib.Utils;

namespace LiteNetLib
{
    public sealed class NetPacketReader : NetDataReader
    {
        private NetPacket _packet;
        private readonly NetManager _manager;
        private readonly NetEvent _evt;

        internal NetPacketReader(NetManager manager, NetEvent evt)
        {
            _manager = manager;
            _evt = evt;
        }

        internal void SetSource(NetPacket packet, int headerSize)
        {
            if (packet == null)
                return;
            _packet = packet;
            SetSource(packet.RawData, headerSize, packet.Size);
        }

        internal void RecycleInternal()
        {
            Clear();
            if (_packet != null)
                _manager.PoolRecycle(_packet);
            _packet = null;
            _manager.RecycleEvent(_evt);
        }

        public void Recycle()
        {
            if (_manager.AutoRecycle)
                return;
            RecycleInternal();
        }
    }

    internal sealed class NetEvent
    {
        public NetEvent Next;

        public enum EType
        {
            Connect,
            Disconnect,
            Receive,
            ReceiveUnconnected,
            Error,
            ConnectionLatencyUpdated,
            Broadcast,
            ConnectionRequest,
            MessageDelivered,
            PeerAddressChanged
        }
        public EType Type;

        public NetPeer Peer;
        public IPEndPoint RemoteEndPoint;
        public object UserData;
        public int Latency;
        public SocketError ErrorCode;
        public DisconnectReason DisconnectReason;
        public ConnectionRequest ConnectionRequest;
        public DeliveryMethod DeliveryMethod;
        public byte ChannelNumber;
        public readonly NetPacketReader DataReader;

        public NetEvent(NetManager manager)
        {
            DataReader = new NetPacketReader(manager, this);
        }
    }

    /// <summary>
    /// Main class for all network operations. Can be used as client and/or server.
    /// </summary>
    public partial class NetManager : IEnumerable<NetPeer>
    {
        public struct NetPeerEnumerator : IEnumerator<NetPeer>
        {
            private readonly NetPeer _initialPeer;
            private NetPeer _p;

            public NetPeerEnumerator(NetPeer p)
            {
                _initialPeer = p;
                _p = null;
            }

            public void Dispose()
            {

            }

            public bool MoveNext()
            {
                _p = _p == null ? _initialPeer : _p.NextPeer;
                return _p != null;
            }

            public void Reset()
            {
                throw new NotSupportedException();
            }

            public NetPeer Current => _p;
            object IEnumerator.Current => _p;
        }

#if DEBUG
        private struct IncomingData
        {
            public NetPacket Data;
            public IPEndPoint EndPoint;
            public DateTime TimeWhenGet;
        }
        private readonly List<IncomingData> _pingSimulationList = new List<IncomingData>();
        private readonly Random _randomGenerator = new Random();
        private const int MinLatencyThreshold = 5;
#endif

        private Thread _logicThread;
        private bool _manualMode;
        private readonly AutoResetEvent _updateTriggerEvent = new AutoResetEvent(true);

        private NetEvent _pendingEventHead;
        private NetEvent _pendingEventTail;

        private NetEvent _netEventPoolHead;
        private readonly INetEventListener _netEventListener;
        private readonly IDeliveryEventListener _deliveryEventListener;
        private readonly INtpEventListener _ntpEventListener;
        private readonly IPeerAddressChangedListener _peerAddressChangedListener;

        private readonly Dictionary<IPEndPoint, ConnectionRequest> _requestsDict = new Dictionary<IPEndPoint, ConnectionRequest>();
        private readonly ConcurrentDictionary<IPEndPoint, NtpRequest> _ntpRequests = new ConcurrentDictionary<IPEndPoint, NtpRequest>();
        private int _connectedPeersCount;
        private readonly List<NetPeer> _connectedPeerListCache = new List<NetPeer>();
        private readonly PacketLayerBase _extraPacketLayer;
        private int _lastPeerId;
        private ConcurrentQueue<int> _peerIds = new ConcurrentQueue<int>();
        private byte _channelsCount = 1;
        private readonly object _eventLock = new object();

        //config section
        /// <summary>
        /// Enable messages receiving without connection. (with SendUnconnectedMessage method)
        /// </summary>
        public bool UnconnectedMessagesEnabled = false;

        /// <summary>
        /// Enable nat punch messages
        /// </summary>
        public bool NatPunchEnabled = false;

        /// <summary>
        /// Library logic update and send period in milliseconds
        /// Lowest values in Windows doesn't change much because of Thread.Sleep precision
        /// To more frequent sends (or sends tied to your game logic) use <see cref="TriggerUpdate"/>
        /// </summary>
        public int UpdateTime = 15;

        /// <summary>
        /// Interval for latency detection and checking connection (in milliseconds)
        /// </summary>
        public int PingInterval = 1000;

        /// <summary>
        /// If NetManager doesn't receive any packet from remote peer during this time (in milliseconds) then connection will be closed
        /// (including library internal keepalive packets)
        /// </summary>
        public int DisconnectTimeout = 5000;

        /// <summary>
        /// Simulate packet loss by dropping random amount of packets. (Works only in DEBUG mode)
        /// </summary>
        public bool SimulatePacketLoss = false;

        /// <summary>
        /// Simulate latency by holding packets for random time. (Works only in DEBUG mode)
        /// </summary>
        public bool SimulateLatency = false;

        /// <summary>
        /// Chance of packet loss when simulation enabled. value in percents (1 - 100).
        /// </summary>
        public int SimulationPacketLossChance = 10;

        /// <summary>
        /// Minimum simulated latency (in milliseconds)
        /// </summary>
        public int SimulationMinLatency = 30;

        /// <summary>
        /// Maximum simulated latency (in milliseconds)
        /// </summary>
        public int SimulationMaxLatency = 100;

        /// <summary>
        /// Events automatically will be called without PollEvents method from another thread
        /// </summary>
        public bool UnsyncedEvents = false;

        /// <summary>
        /// If true - receive event will be called from "receive" thread immediately otherwise on PollEvents call
        /// </summary>
        public bool UnsyncedReceiveEvent = false;

        /// <summary>
        /// If true - delivery event will be called from "receive" thread immediately otherwise on PollEvents call
        /// </summary>
        public bool UnsyncedDeliveryEvent = false;

        /// <summary>
        /// Allows receive broadcast packets
        /// </summary>
        public bool BroadcastReceiveEnabled = false;

        /// <summary>
        /// Delay between initial connection attempts (in milliseconds)
        /// </summary>
        public int ReconnectDelay = 500;

        /// <summary>
        /// Maximum connection attempts before client stops and call disconnect event.
        /// </summary>
        public int MaxConnectAttempts = 10;

        /// <summary>
        /// Enables socket option "ReuseAddress" for specific purposes
        /// </summary>
        public bool ReuseAddress = false;

        /// <summary>
        /// UDP Only Socket Option
        /// Normally IP sockets send packets of data through routers and gateways until they reach the final destination.
        /// If the DontRoute flag is set to True, then data will be delivered on the local subnet only.
        /// </summary>
        public bool DontRoute = false;

        /// <summary>
        /// Statistics of all connections
        /// </summary>
        public readonly NetStatistics Statistics = new NetStatistics();

        /// <summary>
        /// Toggles the collection of network statistics for the instance and all known peers
        /// </summary>
        public bool EnableStatistics = false;

        /// <summary>
        /// NatPunchModule for NAT hole punching operations
        /// </summary>
        public readonly NatPunchModule NatPunchModule;

        /// <summary>
        /// Returns true if socket listening and update thread is running
        /// </summary>
        public bool IsRunning { get; private set; }

        /// <summary>
        /// Local EndPoint (host and port)
        /// </summary>
        public int LocalPort { get; private set; }

        /// <summary>
        /// Automatically recycle NetPacketReader after OnReceive event
        /// </summary>
        public bool AutoRecycle;

        /// <summary>
        /// IPv6 support
        /// </summary>
        public bool IPv6Enabled = true;

        /// <summary>
        /// Override MTU for all new peers registered in this NetManager, will ignores MTU Discovery!
        /// </summary>
        public int MtuOverride = 0;

        /// <summary>
        /// Sets initial MTU to lowest possible value according to RFC1191 (576 bytes)
        /// </summary>
        public bool UseSafeMtu = false;

        /// <summary>
        /// First peer. Useful for Client mode
        /// </summary>
        public NetPeer FirstPeer => _headPeer;

        /// <summary>
        /// Experimental feature mostly for servers. Only for Windows/Linux
        /// use direct socket calls for send/receive to drastically increase speed and reduce GC pressure
        /// </summary>
        public bool UseNativeSockets = false;

        /// <summary>
        /// Disconnect peers if HostUnreachable or NetworkUnreachable spawned (old behaviour 0.9.x was true)
        /// </summary>
        public bool DisconnectOnUnreachable = false;

        /// <summary>
        /// Allows peer change it's ip (lte to wifi, wifi to lte, etc). Use only on server
        /// </summary>
        public bool AllowPeerAddressChange = false;

        /// <summary>
        /// QoS channel count per message type (value must be between 1 and 64 channels)
        /// </summary>
        public byte ChannelsCount
        {
            get => _channelsCount;
            set
            {
                if (value < 1 || value > 64)
                    throw new ArgumentException("Channels count must be between 1 and 64");
                _channelsCount = value;
            }
        }

        /// <summary>
        /// Returns connected peers list (with internal cached list)
        /// </summary>
        public List<NetPeer> ConnectedPeerList
        {
            get
            {
                GetPeersNonAlloc(_connectedPeerListCache, ConnectionState.Connected);
                return _connectedPeerListCache;
            }
        }

        /// <summary>
        /// Returns connected peers count
        /// </summary>
        public int ConnectedPeersCount => Interlocked.CompareExchange(ref _connectedPeersCount,0,0);

        public int ExtraPacketSizeForLayer => _extraPacketLayer?.ExtraPacketSizeForLayer ?? 0;

        /// <summary>
        /// NetManager constructor
        /// </summary>
        /// <param name="listener">Network events listener (also can implement IDeliveryEventListener)</param>
        /// <param name="extraPacketLayer">Extra processing of packages, like CRC checksum or encryption. All connected NetManagers must have same layer.</param>
        public NetManager(INetEventListener listener, PacketLayerBase extraPacketLayer = null)
        {
            _netEventListener = listener;
            _deliveryEventListener = listener as IDeliveryEventListener;
            _ntpEventListener = listener as INtpEventListener;
            _peerAddressChangedListener = listener as IPeerAddressChangedListener;
            NatPunchModule = new NatPunchModule(this);
            _extraPacketLayer = extraPacketLayer;
        }

        internal void ConnectionLatencyUpdated(NetPeer fromPeer, int latency)
        {
            CreateEvent(NetEvent.EType.ConnectionLatencyUpdated, fromPeer, latency: latency);
        }

        internal void MessageDelivered(NetPeer fromPeer, object userData)
        {
            if(_deliveryEventListener != null)
                CreateEvent(NetEvent.EType.MessageDelivered, fromPeer, userData: userData);
        }

        internal void DisconnectPeerForce(NetPeer peer,
            DisconnectReason reason,
            SocketError socketErrorCode,
            NetPacket eventData)
        {
            DisconnectPeer(peer, reason, socketErrorCode, true, null, 0, 0, eventData);
        }

        private void DisconnectPeer(
            NetPeer peer,
            DisconnectReason reason,
            SocketError socketErrorCode,
            bool force,
            byte[] data,
            int start,
            int count,
            NetPacket eventData)
        {
            var shutdownResult = peer.Shutdown(data, start, count, force);
            if (shutdownResult == ShutdownResult.None)
                return;
            if(shutdownResult == ShutdownResult.WasConnected)
                Interlocked.Decrement(ref _connectedPeersCount);
            CreateEvent(
                NetEvent.EType.Disconnect,
                peer,
                errorCode: socketErrorCode,
                disconnectReason: reason,
                readerSource: eventData);
        }

        private void CreateEvent(
            NetEvent.EType type,
            NetPeer peer = null,
            IPEndPoint remoteEndPoint = null,
            SocketError errorCode = 0,
            int latency = 0,
            DisconnectReason disconnectReason = DisconnectReason.ConnectionFailed,
            ConnectionRequest connectionRequest = null,
            DeliveryMethod deliveryMethod = DeliveryMethod.Unreliable,
            byte channelNumber = 0,
            NetPacket readerSource = null,
            object userData = null)
        {
            NetEvent evt;
            bool unsyncEvent = UnsyncedEvents;

            if (type == NetEvent.EType.Connect)
                Interlocked.Increment(ref _connectedPeersCount);
            else if (type == NetEvent.EType.MessageDelivered)
                unsyncEvent = UnsyncedDeliveryEvent;

            lock(_eventLock)
            {
                evt = _netEventPoolHead;
                if (evt == null)
                    evt = new NetEvent(this);
                else
                    _netEventPoolHead = evt.Next;
            }

            evt.Next = null;
            evt.Type = type;
            evt.DataReader.SetSource(readerSource, readerSource?.GetHeaderSize() ?? 0);
            evt.Peer = peer;
            evt.RemoteEndPoint = remoteEndPoint;
            evt.Latency = latency;
            evt.ErrorCode = errorCode;
            evt.DisconnectReason = disconnectReason;
            evt.ConnectionRequest = connectionRequest;
            evt.DeliveryMethod = deliveryMethod;
            evt.ChannelNumber = channelNumber;
            evt.UserData = userData;

            if (unsyncEvent || _manualMode)
            {
                ProcessEvent(evt);
            }
            else
            {
                lock (_eventLock)
                {
                    if (_pendingEventTail == null)
                        _pendingEventHead = evt;
                    else
                        _pendingEventTail.Next = evt;
                    _pendingEventTail = evt;
                }
            }
        }

        private void ProcessEvent(NetEvent evt)
        {
            NetDebug.Write("[NM] Processing event: " + evt.Type);
            bool emptyData = evt.DataReader.IsNull;
            switch (evt.Type)
            {
                case NetEvent.EType.Connect:
                    _netEventListener.OnPeerConnected(evt.Peer);
                    break;
                case NetEvent.EType.Disconnect:
                    var info = new DisconnectInfo
                    {
                        Reason = evt.DisconnectReason,
                        AdditionalData = evt.DataReader,
                        SocketErrorCode = evt.ErrorCode
                    };
                    _netEventListener.OnPeerDisconnected(evt.Peer, info);
                    break;
                case NetEvent.EType.Receive:
                    _netEventListener.OnNetworkReceive(evt.Peer, evt.DataReader, evt.ChannelNumber, evt.DeliveryMethod);
                    break;
                case NetEvent.EType.ReceiveUnconnected:
                    _netEventListener.OnNetworkReceiveUnconnected(evt.RemoteEndPoint, evt.DataReader, UnconnectedMessageType.BasicMessage);
                    break;
                case NetEvent.EType.Broadcast:
                    _netEventListener.OnNetworkReceiveUnconnected(evt.RemoteEndPoint, evt.DataReader, UnconnectedMessageType.Broadcast);
                    break;
                case NetEvent.EType.Error:
                    _netEventListener.OnNetworkError(evt.RemoteEndPoint, evt.ErrorCode);
                    break;
                case NetEvent.EType.ConnectionLatencyUpdated:
                    _netEventListener.OnNetworkLatencyUpdate(evt.Peer, evt.Latency);
                    break;
                case NetEvent.EType.ConnectionRequest:
                    _netEventListener.OnConnectionRequest(evt.ConnectionRequest);
                    break;
                case NetEvent.EType.MessageDelivered:
                    _deliveryEventListener.OnMessageDelivered(evt.Peer, evt.UserData);
                    break;
                case NetEvent.EType.PeerAddressChanged:
                    _peersLock.EnterUpgradeableReadLock();
                    IPEndPoint previousAddress = null;
                    if (ContainsPeer(evt.Peer))
                    {
                        _peersLock.EnterWriteLock();
                        RemovePeerFromSet(evt.Peer);
                        previousAddress = new IPEndPoint(evt.Peer.Address, evt.Peer.Port);
                        evt.Peer.FinishEndPointChange(evt.RemoteEndPoint);
                        AddPeerToSet(evt.Peer);
                        _peersLock.ExitWriteLock();
                    }
                    _peersLock.ExitUpgradeableReadLock();
                    if(previousAddress != null && _peerAddressChangedListener != null)
                        _peerAddressChangedListener.OnPeerAddressChanged(evt.Peer, previousAddress);
                    break;
            }
            //Recycle if not message
            if (emptyData)
                RecycleEvent(evt);
            else if (AutoRecycle)
                evt.DataReader.RecycleInternal();
        }

        internal void RecycleEvent(NetEvent evt)
        {
            evt.Peer = null;
            evt.ErrorCode = 0;
            evt.RemoteEndPoint = null;
            evt.ConnectionRequest = null;
            lock(_eventLock)
            {
                evt.Next = _netEventPoolHead;
                _netEventPoolHead = evt;
            }
        }

        //Update function
        private void UpdateLogic()
        {
            var peersToRemove = new List<NetPeer>();
            var stopwatch = new Stopwatch();
            stopwatch.Start();

            while (IsRunning)
            {
                try
                {
                    ProcessDelayedPackets();
                    int elapsed = (int)stopwatch.ElapsedMilliseconds;
                    elapsed = elapsed <= 0 ? 1 : elapsed;
                    stopwatch.Restart();

                    for (var netPeer = _headPeer; netPeer != null; netPeer = netPeer.NextPeer)
                    {
                        if (netPeer.ConnectionState == ConnectionState.Disconnected &&
                            netPeer.TimeSinceLastPacket > DisconnectTimeout)
                        {
                            peersToRemove.Add(netPeer);
                        }
                        else
                        {
                            netPeer.Update(elapsed);
                        }
                    }

                    if (peersToRemove.Count > 0)
                    {
                        _peersLock.EnterWriteLock();
                        for (int i = 0; i < peersToRemove.Count; i++)
                            RemovePeerInternal(peersToRemove[i]);
                        _peersLock.ExitWriteLock();
                        peersToRemove.Clear();
                    }

                    ProcessNtpRequests(elapsed);

                    int sleepTime = UpdateTime - (int)stopwatch.ElapsedMilliseconds;
                    if (sleepTime > 0)
                        _updateTriggerEvent.WaitOne(sleepTime);
                }
                catch (ThreadAbortException)
                {
                    return;
                }
                catch (Exception e)
                {
                    NetDebug.WriteError("[NM] LogicThread error: " + e);
                }
            }
            stopwatch.Stop();
        }

        [Conditional("DEBUG")]
        private void ProcessDelayedPackets()
        {
#if DEBUG
            if (!SimulateLatency)
                return;

            var time = DateTime.UtcNow;
            lock (_pingSimulationList)
            {
                for (int i = 0; i < _pingSimulationList.Count; i++)
                {
                    var incomingData = _pingSimulationList[i];
                    if (incomingData.TimeWhenGet <= time)
                    {
                        DebugMessageReceived(incomingData.Data, incomingData.EndPoint);
                        _pingSimulationList.RemoveAt(i);
                        i--;
                    }
                }
            }
#endif
        }

        private void ProcessNtpRequests(int elapsedMilliseconds)
        {
            List<IPEndPoint> requestsToRemove = null;
            foreach (var ntpRequest in _ntpRequests)
            {
                ntpRequest.Value.Send(_udpSocketv4, elapsedMilliseconds);
                if(ntpRequest.Value.NeedToKill)
                {
                    if (requestsToRemove == null)
                        requestsToRemove = new List<IPEndPoint>();
                    requestsToRemove.Add(ntpRequest.Key);
                }
            }

            if (requestsToRemove != null)
            {
                foreach (var ipEndPoint in requestsToRemove)
                {
                    _ntpRequests.TryRemove(ipEndPoint, out _);
                }
            }
        }

        /// <summary>
        /// Update and send logic. Use this only when NetManager started in manual mode
        /// </summary>
        /// <param name="elapsedMilliseconds">elapsed milliseconds since last update call</param>
        public void ManualUpdate(int elapsedMilliseconds)
        {
            if (!_manualMode)
                return;

            for (var netPeer = _headPeer; netPeer != null; netPeer = netPeer.NextPeer)
            {
                if (netPeer.ConnectionState == ConnectionState.Disconnected && netPeer.TimeSinceLastPacket > DisconnectTimeout)
                {
                    RemovePeerInternal(netPeer);
                }
                else
                {
                    netPeer.Update(elapsedMilliseconds);
                }
            }
            ProcessNtpRequests(elapsedMilliseconds);
        }

        internal NetPeer OnConnectionSolved(ConnectionRequest request, byte[] rejectData, int start, int length)
        {
            NetPeer netPeer = null;

            if (request.Result == ConnectionRequestResult.RejectForce)
            {
                NetDebug.Write(NetLogLevel.Trace, "[NM] Peer connect reject force.");
                if (rejectData != null && length > 0)
                {
                    var shutdownPacket = PoolGetWithProperty(PacketProperty.Disconnect, length);
                    shutdownPacket.ConnectionNumber = request.InternalPacket.ConnectionNumber;
                    FastBitConverter.GetBytes(shutdownPacket.RawData, 1, request.InternalPacket.ConnectionTime);
                    if (shutdownPacket.Size >= NetConstants.PossibleMtu[0])
                        NetDebug.WriteError("[Peer] Disconnect additional data size more than MTU!");
                    else
                        Buffer.BlockCopy(rejectData, start, shutdownPacket.RawData, 9, length);
                    SendRawAndRecycle(shutdownPacket, request.RemoteEndPoint);
                }
                lock (_requestsDict)
                    _requestsDict.Remove(request.RemoteEndPoint);
            }
            else lock (_requestsDict)
            {
                if (TryGetPeer(request.RemoteEndPoint, out netPeer))
                {
                    //already have peer
                }
                else if (request.Result == ConnectionRequestResult.Reject)
                {
                    netPeer = new NetPeer(this, request.RemoteEndPoint, GetNextPeerId());
                    netPeer.Reject(request.InternalPacket, rejectData, start, length);
                    AddPeer(netPeer);
                    NetDebug.Write(NetLogLevel.Trace, "[NM] Peer connect reject.");
                }
                else //Accept
                {
                    netPeer = new NetPeer(this, request, GetNextPeerId());
                    AddPeer(netPeer);
                    CreateEvent(NetEvent.EType.Connect, netPeer);
                    NetDebug.Write(NetLogLevel.Trace, $"[NM] Received peer connection Id: {netPeer.ConnectTime}, EP: {netPeer}");
                }
                _requestsDict.Remove(request.RemoteEndPoint);
            }

            return netPeer;
        }

        private int GetNextPeerId()
        {
            return _peerIds.TryDequeue(out int id) ? id : _lastPeerId++;
        }

        private void ProcessConnectRequest(
            IPEndPoint remoteEndPoint,
            NetPeer netPeer,
            NetConnectRequestPacket connRequest)
        {
            //if we have peer
            if (netPeer != null)
            {
                var processResult = netPeer.ProcessConnectRequest(connRequest);
                NetDebug.Write($"ConnectRequest LastId: {netPeer.ConnectTime}, NewId: {connRequest.ConnectionTime}, EP: {remoteEndPoint}, Result: {processResult}");

                switch (processResult)
                {
                    case ConnectRequestResult.Reconnection:
                        DisconnectPeerForce(netPeer, DisconnectReason.Reconnect, 0, null);
                        RemovePeer(netPeer);
                        //go to new connection
                        break;
                    case ConnectRequestResult.NewConnection:
                        RemovePeer(netPeer);
                        //go to new connection
                        break;
                    case ConnectRequestResult.P2PLose:
                        DisconnectPeerForce(netPeer, DisconnectReason.PeerToPeerConnection, 0, null);
                        RemovePeer(netPeer);
                        //go to new connection
                        break;
                    default:
                        //no operations needed
                        return;
                }
                //ConnectRequestResult.NewConnection
                //Set next connection number
                if(processResult != ConnectRequestResult.P2PLose)
                    connRequest.ConnectionNumber = (byte)((netPeer.ConnectionNum + 1) % NetConstants.MaxConnectionNumber);
                //To reconnect peer
            }
            else
            {
                NetDebug.Write($"ConnectRequest Id: {connRequest.ConnectionTime}, EP: {remoteEndPoint}");
            }

            ConnectionRequest req;
            lock (_requestsDict)
            {
                if (_requestsDict.TryGetValue(remoteEndPoint, out req))
                {
                    req.UpdateRequest(connRequest);
                    return;
                }
                req = new ConnectionRequest(remoteEndPoint, connRequest, this);
                _requestsDict.Add(remoteEndPoint, req);
            }
            NetDebug.Write($"[NM] Creating request event: {connRequest.ConnectionTime}");
            CreateEvent(NetEvent.EType.ConnectionRequest, connectionRequest: req);
        }

        private void OnMessageReceived(NetPacket packet, IPEndPoint remoteEndPoint)
        {
            if (packet.Size == 0)
            {
                PoolRecycle(packet);
                return;
            }
#if DEBUG
            if (SimulatePacketLoss && _randomGenerator.NextDouble() * 100 < SimulationPacketLossChance)
            {
                //drop packet
                return;
            }
            if (SimulateLatency)
            {
                int latency = _randomGenerator.Next(SimulationMinLatency, SimulationMaxLatency);
                if (latency > MinLatencyThreshold)
                {
                    lock (_pingSimulationList)
                    {
                        _pingSimulationList.Add(new IncomingData
                        {
                            Data = packet,
                            EndPoint = remoteEndPoint,
                            TimeWhenGet = DateTime.UtcNow.AddMilliseconds(latency)
                        });
                    }
                    //hold packet
                    return;
                }
            }

            //ProcessEvents
            DebugMessageReceived(packet, remoteEndPoint);
        }

        private void DebugMessageReceived(NetPacket packet, IPEndPoint remoteEndPoint)
        {
#endif
            var originalPacketSize = packet.Size;
            if (EnableStatistics)
            {
                Statistics.IncrementPacketsReceived();
                Statistics.AddBytesReceived(originalPacketSize);
            }

            if (_ntpRequests.Count > 0 && _ntpRequests.TryGetValue(remoteEndPoint, out var request))
            {
                if (packet.Size < 48)
                {
                    NetDebug.Write(NetLogLevel.Trace, $"NTP response too short: {packet.Size}");
                    return;
                }

                byte[] copiedData = new byte[packet.Size];
                Buffer.BlockCopy(packet.RawData, 0, copiedData, 0, packet.Size);
                NtpPacket ntpPacket = NtpPacket.FromServerResponse(copiedData, DateTime.UtcNow);
                try
                {
                    ntpPacket.ValidateReply();
                }
                catch (InvalidOperationException ex)
                {
                    NetDebug.Write(NetLogLevel.Trace, $"NTP response error: {ex.Message}");
                    ntpPacket = null;
                }

                if (ntpPacket != null)
                {
                    _ntpRequests.TryRemove(remoteEndPoint, out _);
                    _ntpEventListener?.OnNtpResponse(ntpPacket);
                }
                return;
            }

            if (_extraPacketLayer != null)
            {
                _extraPacketLayer.ProcessInboundPacket(ref remoteEndPoint, ref packet.RawData, ref packet.Size);
                if (packet.Size == 0)
                    return;
            }

            if (!packet.Verify())
            {
                NetDebug.WriteError("[NM] DataReceived: bad!");
                PoolRecycle(packet);
                return;
            }

            switch (packet.Property)
            {
                //special case connect request
                case PacketProperty.ConnectRequest:
                    if (NetConnectRequestPacket.GetProtocolId(packet) != NetConstants.ProtocolId)
                    {
                        SendRawAndRecycle(PoolGetWithProperty(PacketProperty.InvalidProtocol), remoteEndPoint);
                        return;
                    }
                    break;
                //unconnected messages
                case PacketProperty.Broadcast:
                    if (!BroadcastReceiveEnabled)
                        return;
                    CreateEvent(NetEvent.EType.Broadcast, remoteEndPoint: remoteEndPoint, readerSource: packet);
                    return;
                case PacketProperty.UnconnectedMessage:
                    if (!UnconnectedMessagesEnabled)
                        return;
                    CreateEvent(NetEvent.EType.ReceiveUnconnected, remoteEndPoint: remoteEndPoint, readerSource: packet);
                    return;
                case PacketProperty.NatMessage:
                    if (NatPunchEnabled)
                        NatPunchModule.ProcessMessage(remoteEndPoint, packet);
                    return;
            }

            //Check normal packets
            bool peerFound = remoteEndPoint is NetPeer netPeer || TryGetPeer(remoteEndPoint, out netPeer);

            if (peerFound && EnableStatistics)
            {
                netPeer.Statistics.IncrementPacketsReceived();
                netPeer.Statistics.AddBytesReceived(originalPacketSize);
            }

            switch (packet.Property)
            {
                case PacketProperty.ConnectRequest:
                    var connRequest = NetConnectRequestPacket.FromData(packet);
                    if (connRequest != null)
                        ProcessConnectRequest(remoteEndPoint, netPeer, connRequest);
                    break;
                case PacketProperty.PeerNotFound:
                    if (peerFound) //local
                    {
                        if (netPeer.ConnectionState != ConnectionState.Connected)
                            return;
                        if (packet.Size == 1)
                        {
                            //first reply
                            //send NetworkChanged packet
                            netPeer.ResetMtu();
                            SendRaw(NetConnectAcceptPacket.MakeNetworkChanged(netPeer), remoteEndPoint);
                            NetDebug.Write($"PeerNotFound sending connection info: {remoteEndPoint}");
                        }
                        else if (packet.Size == 2 && packet.RawData[1] == 1)
                        {
                            //second reply
                            DisconnectPeerForce(netPeer, DisconnectReason.PeerNotFound, 0, null);
                        }
                    }
                    else if (packet.Size > 1) //remote
                    {
                        //check if this is old peer
                        bool isOldPeer = false;

                        if (AllowPeerAddressChange)
                        {
                            NetDebug.Write($"[NM] Looks like address change: {packet.Size}");
                            var remoteData = NetConnectAcceptPacket.FromData(packet);
                            if (remoteData != null &&
                                remoteData.PeerNetworkChanged &&
                                remoteData.PeerId < _peersArray.Length)
                            {
                                _peersLock.EnterUpgradeableReadLock();
                                var peer = _peersArray[remoteData.PeerId];
                                _peersLock.ExitUpgradeableReadLock();
                                if (peer != null &&
                                    peer.ConnectTime == remoteData.ConnectionTime &&
                                    peer.ConnectionNum == remoteData.ConnectionNumber)
                                {
                                    if (peer.ConnectionState == ConnectionState.Connected)
                                    {
                                        peer.InitiateEndPointChange();
                                        CreateEvent(NetEvent.EType.PeerAddressChanged, peer, remoteEndPoint);
                                        NetDebug.Write("[NM] PeerNotFound change address of remote peer");
                                    }
                                    isOldPeer = true;
                                }
                            }
                        }

                        PoolRecycle(packet);

                        //else peer really not found
                        if (!isOldPeer)
                        {
                            var secondResponse = PoolGetWithProperty(PacketProperty.PeerNotFound, 1);
                            secondResponse.RawData[1] = 1;
                            SendRawAndRecycle(secondResponse, remoteEndPoint);
                        }
                    }
                    break;
                case PacketProperty.InvalidProtocol:
                    if (peerFound && netPeer.ConnectionState == ConnectionState.Outgoing)
                        DisconnectPeerForce(netPeer, DisconnectReason.InvalidProtocol, 0, null);
                    break;
                case PacketProperty.Disconnect:
                    if (peerFound)
                    {
                        var disconnectResult = netPeer.ProcessDisconnect(packet);
                        if (disconnectResult == DisconnectResult.None)
                        {
                            PoolRecycle(packet);
                            return;
                        }
                        DisconnectPeerForce(
                            netPeer,
                            disconnectResult == DisconnectResult.Disconnect
                            ? DisconnectReason.RemoteConnectionClose
                            : DisconnectReason.ConnectionRejected,
                            0, packet);
                    }
                    else
                    {
                        PoolRecycle(packet);
                    }
                    //Send shutdown
                    SendRawAndRecycle(PoolGetWithProperty(PacketProperty.ShutdownOk), remoteEndPoint);
                    break;
                case PacketProperty.ConnectAccept:
                    if (!peerFound)
                        return;
                    var connAccept = NetConnectAcceptPacket.FromData(packet);
                    if (connAccept != null && netPeer.ProcessConnectAccept(connAccept))
                        CreateEvent(NetEvent.EType.Connect, netPeer);
                    break;
                default:
                    if(peerFound)
                        netPeer.ProcessPacket(packet);
                    else
                        SendRawAndRecycle(PoolGetWithProperty(PacketProperty.PeerNotFound), remoteEndPoint);
                    break;
            }
        }

        internal void CreateReceiveEvent(NetPacket packet, DeliveryMethod method, byte channelNumber, int headerSize, NetPeer fromPeer)
        {
            NetEvent evt;

            if (UnsyncedEvents || UnsyncedReceiveEvent || _manualMode)
            {
                lock (_eventLock)
                {
                    evt = _netEventPoolHead;
                    if (evt == null)
                        evt = new NetEvent(this);
                    else
                        _netEventPoolHead = evt.Next;
                }
                evt.Next = null;
                evt.Type = NetEvent.EType.Receive;
                evt.DataReader.SetSource(packet, headerSize);
                evt.Peer = fromPeer;
                evt.DeliveryMethod = method;
                evt.ChannelNumber = channelNumber;
                ProcessEvent(evt);
            }
            else
            {
                lock (_eventLock)
                {
                    evt = _netEventPoolHead;
                    if (evt == null)
                        evt = new NetEvent(this);
                    else
                        _netEventPoolHead = evt.Next;

                    evt.Next = null;
                    evt.Type = NetEvent.EType.Receive;
                    evt.DataReader.SetSource(packet, headerSize);
                    evt.Peer = fromPeer;
                    evt.DeliveryMethod = method;
                    evt.ChannelNumber = channelNumber;

                    if (_pendingEventTail == null)
                        _pendingEventHead = evt;
                    else
                        _pendingEventTail.Next = evt;
                    _pendingEventTail = evt;
                }
            }
        }

        /// <summary>
        /// Send data to all connected peers (channel - 0)
        /// </summary>
        /// <param name="writer">DataWriter with data</param>
        /// <param name="options">Send options (reliable, unreliable, etc.)</param>
        public void SendToAll(NetDataWriter writer, DeliveryMethod options)
        {
            SendToAll(writer.Data, 0, writer.Length, options);
        }

        /// <summary>
        /// Send data to all connected peers (channel - 0)
        /// </summary>
        /// <param name="data">Data</param>
        /// <param name="options">Send options (reliable, unreliable, etc.)</param>
        public void SendToAll(byte[] data, DeliveryMethod options)
        {
            SendToAll(data, 0, data.Length, options);
        }

        /// <summary>
        /// Send data to all connected peers (channel - 0)
        /// </summary>
        /// <param name="data">Data</param>
        /// <param name="start">Start of data</param>
        /// <param name="length">Length of data</param>
        /// <param name="options">Send options (reliable, unreliable, etc.)</param>
        public void SendToAll(byte[] data, int start, int length, DeliveryMethod options)
        {
            SendToAll(data, start, length, 0, options);
        }

        /// <summary>
        /// Send data to all connected peers
        /// </summary>
        /// <param name="writer">DataWriter with data</param>
        /// <param name="channelNumber">Number of channel (from 0 to channelsCount - 1)</param>
        /// <param name="options">Send options (reliable, unreliable, etc.)</param>
        public void SendToAll(NetDataWriter writer, byte channelNumber, DeliveryMethod options)
        {
            SendToAll(writer.Data, 0, writer.Length, channelNumber, options);
        }

        /// <summary>
        /// Send data to all connected peers
        /// </summary>
        /// <param name="data">Data</param>
        /// <param name="channelNumber">Number of channel (from 0 to channelsCount - 1)</param>
        /// <param name="options">Send options (reliable, unreliable, etc.)</param>
        public void SendToAll(byte[] data, byte channelNumber, DeliveryMethod options)
        {
            SendToAll(data, 0, data.Length, channelNumber, options);
        }

        /// <summary>
        /// Send data to all connected peers
        /// </summary>
        /// <param name="data">Data</param>
        /// <param name="start">Start of data</param>
        /// <param name="length">Length of data</param>
        /// <param name="channelNumber">Number of channel (from 0 to channelsCount - 1)</param>
        /// <param name="options">Send options (reliable, unreliable, etc.)</param>
        public void SendToAll(byte[] data, int start, int length, byte channelNumber, DeliveryMethod options)
        {
            try
            {
                _peersLock.EnterReadLock();
                for (var netPeer = _headPeer; netPeer != null; netPeer = netPeer.NextPeer)
                    netPeer.Send(data, start, length, channelNumber, options);
            }
            finally
            {
                _peersLock.ExitReadLock();
            }
        }

        /// <summary>
        /// Send data to all connected peers (channel - 0)
        /// </summary>
        /// <param name="writer">DataWriter with data</param>
        /// <param name="options">Send options (reliable, unreliable, etc.)</param>
        /// <param name="excludePeer">Excluded peer</param>
        public void SendToAll(NetDataWriter writer, DeliveryMethod options, NetPeer excludePeer)
        {
            SendToAll(writer.Data, 0, writer.Length, 0, options, excludePeer);
        }

        /// <summary>
        /// Send data to all connected peers (channel - 0)
        /// </summary>
        /// <param name="data">Data</param>
        /// <param name="options">Send options (reliable, unreliable, etc.)</param>
        /// <param name="excludePeer">Excluded peer</param>
        public void SendToAll(byte[] data, DeliveryMethod options, NetPeer excludePeer)
        {
            SendToAll(data, 0, data.Length, 0, options, excludePeer);
        }

        /// <summary>
        /// Send data to all connected peers (channel - 0)
        /// </summary>
        /// <param name="data">Data</param>
        /// <param name="start">Start of data</param>
        /// <param name="length">Length of data</param>
        /// <param name="options">Send options (reliable, unreliable, etc.)</param>
        /// <param name="excludePeer">Excluded peer</param>
        public void SendToAll(byte[] data, int start, int length, DeliveryMethod options, NetPeer excludePeer)
        {
            SendToAll(data, start, length, 0, options, excludePeer);
        }

        /// <summary>
        /// Send data to all connected peers
        /// </summary>
        /// <param name="writer">DataWriter with data</param>
        /// <param name="channelNumber">Number of channel (from 0 to channelsCount - 1)</param>
        /// <param name="options">Send options (reliable, unreliable, etc.)</param>
        /// <param name="excludePeer">Excluded peer</param>
        public void SendToAll(NetDataWriter writer, byte channelNumber, DeliveryMethod options, NetPeer excludePeer)
        {
            SendToAll(writer.Data, 0, writer.Length, channelNumber, options, excludePeer);
        }

        /// <summary>
        /// Send data to all connected peers
        /// </summary>
        /// <param name="data">Data</param>
        /// <param name="channelNumber">Number of channel (from 0 to channelsCount - 1)</param>
        /// <param name="options">Send options (reliable, unreliable, etc.)</param>
        /// <param name="excludePeer">Excluded peer</param>
        public void SendToAll(byte[] data, byte channelNumber, DeliveryMethod options, NetPeer excludePeer)
        {
            SendToAll(data, 0, data.Length, channelNumber, options, excludePeer);
        }

        /// <summary>
        /// Send data to all connected peers
        /// </summary>
        /// <param name="data">Data</param>
        /// <param name="start">Start of data</param>
        /// <param name="length">Length of data</param>
        /// <param name="channelNumber">Number of channel (from 0 to channelsCount - 1)</param>
        /// <param name="options">Send options (reliable, unreliable, etc.)</param>
        /// <param name="excludePeer">Excluded peer</param>
        public void SendToAll(byte[] data, int start, int length, byte channelNumber, DeliveryMethod options, NetPeer excludePeer)
        {
            try
            {
                _peersLock.EnterReadLock();
                for (var netPeer = _headPeer; netPeer != null; netPeer = netPeer.NextPeer)
                {
                    if (netPeer != excludePeer)
                        netPeer.Send(data, start, length, channelNumber, options);
                }
            }
            finally
            {
                _peersLock.ExitReadLock();
            }
        }

#if LITENETLIB_SPANS || NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER || NETCOREAPP2_1 || NETCOREAPP3_1 || NET5_0 || NETSTANDARD2_1
        /// <summary>
        /// Send data to all connected peers (channel - 0)
        /// </summary>
        /// <param name="data">Data</param>
        /// <param name="options">Send options (reliable, unreliable, etc.)</param>
        public void SendToAll(ReadOnlySpan<byte> data, DeliveryMethod options)
        {
            SendToAll(data, 0, options, null);
        }

        /// <summary>
        /// Send data to all connected peers (channel - 0)
        /// </summary>
        /// <param name="data">Data</param>
        /// <param name="options">Send options (reliable, unreliable, etc.)</param>
        /// <param name="excludePeer">Excluded peer</param>
        public void SendToAll(ReadOnlySpan<byte> data, DeliveryMethod options, NetPeer excludePeer)
        {
            SendToAll(data, 0, options, excludePeer);
        }

        /// <summary>
        /// Send data to all connected peers
        /// </summary>
        /// <param name="data">Data</param>
        /// <param name="channelNumber">Number of channel (from 0 to channelsCount - 1)</param>
        /// <param name="options">Send options (reliable, unreliable, etc.)</param>
        /// <param name="excludePeer">Excluded peer</param>
        public void SendToAll(ReadOnlySpan<byte> data, byte channelNumber, DeliveryMethod options, NetPeer excludePeer)
        {
            try
            {
                _peersLock.EnterReadLock();
                for (var netPeer = _headPeer; netPeer != null; netPeer = netPeer.NextPeer)
                {
                    if (netPeer != excludePeer)
                        netPeer.Send(data, channelNumber, options);
                }
            }
            finally
            {
                _peersLock.ExitReadLock();
            }
        }
#endif

        /// <summary>
        /// Start logic thread and listening on available port
        /// </summary>
        public bool Start()
        {
            return Start(0);
        }

        /// <summary>
        /// Start logic thread and listening on selected port
        /// </summary>
        /// <param name="addressIPv4">bind to specific ipv4 address</param>
        /// <param name="addressIPv6">bind to specific ipv6 address</param>
        /// <param name="port">port to listen</param>
        public bool Start(IPAddress addressIPv4, IPAddress addressIPv6, int port)
        {
            return Start(addressIPv4, addressIPv6, port, false);
        }

        /// <summary>
        /// Start logic thread and listening on selected port
        /// </summary>
        /// <param name="addressIPv4">bind to specific ipv4 address</param>
        /// <param name="addressIPv6">bind to specific ipv6 address</param>
        /// <param name="port">port to listen</param>
        public bool Start(string addressIPv4, string addressIPv6, int port)
        {
            IPAddress ipv4 = NetUtils.ResolveAddress(addressIPv4);
            IPAddress ipv6 = NetUtils.ResolveAddress(addressIPv6);
            return Start(ipv4, ipv6, port);
        }

        /// <summary>
        /// Start logic thread and listening on selected port
        /// </summary>
        /// <param name="port">port to listen</param>
        public bool Start(int port)
        {
            return Start(IPAddress.Any, IPAddress.IPv6Any, port);
        }

        /// <summary>
        /// Start in manual mode and listening on selected port
        /// In this mode you should use ManualReceive (without PollEvents) for receive packets
        /// and ManualUpdate(...) for update and send packets
        /// This mode useful mostly for single-threaded servers
        /// </summary>
        /// <param name="addressIPv4">bind to specific ipv4 address</param>
        /// <param name="addressIPv6">bind to specific ipv6 address</param>
        /// <param name="port">port to listen</param>
        public bool StartInManualMode(IPAddress addressIPv4, IPAddress addressIPv6, int port)
        {
            return Start(addressIPv4, addressIPv6, port, true);
        }

        /// <summary>
        /// Start in manual mode and listening on selected port
        /// In this mode you should use ManualReceive (without PollEvents) for receive packets
        /// and ManualUpdate(...) for update and send packets
        /// This mode useful mostly for single-threaded servers
        /// </summary>
        /// <param name="addressIPv4">bind to specific ipv4 address</param>
        /// <param name="addressIPv6">bind to specific ipv6 address</param>
        /// <param name="port">port to listen</param>
        public bool StartInManualMode(string addressIPv4, string addressIPv6, int port)
        {
            IPAddress ipv4 = NetUtils.ResolveAddress(addressIPv4);
            IPAddress ipv6 = NetUtils.ResolveAddress(addressIPv6);
            return StartInManualMode(ipv4, ipv6, port);
        }

        /// <summary>
        /// Start in manual mode and listening on selected port
        /// In this mode you should use ManualReceive (without PollEvents) for receive packets
        /// and ManualUpdate(...) for update and send packets
        /// This mode useful mostly for single-threaded servers
        /// </summary>
        /// <param name="port">port to listen</param>
        public bool StartInManualMode(int port)
        {
            return StartInManualMode(IPAddress.Any, IPAddress.IPv6Any, port);
        }

        /// <summary>
        /// Send message without connection
        /// </summary>
        /// <param name="message">Raw data</param>
        /// <param name="remoteEndPoint">Packet destination</param>
        /// <returns>Operation result</returns>
        public bool SendUnconnectedMessage(byte[] message, IPEndPoint remoteEndPoint)
        {
            return SendUnconnectedMessage(message, 0, message.Length, remoteEndPoint);
        }

        /// <summary>
        /// Send message without connection. WARNING This method allocates a new IPEndPoint object and
        /// synchronously makes a DNS request. If you're calling this method every frame it will be
        /// much faster to just cache the IPEndPoint.
        /// </summary>
        /// <param name="writer">Data serializer</param>
        /// <param name="address">Packet destination IP or hostname</param>
        /// <param name="port">Packet destination port</param>
        /// <returns>Operation result</returns>
        public bool SendUnconnectedMessage(NetDataWriter writer, string address, int port)
        {
            IPEndPoint remoteEndPoint = NetUtils.MakeEndPoint(address, port);

            return SendUnconnectedMessage(writer.Data, 0, writer.Length, remoteEndPoint);
        }

        /// <summary>
        /// Send message without connection
        /// </summary>
        /// <param name="writer">Data serializer</param>
        /// <param name="remoteEndPoint">Packet destination</param>
        /// <returns>Operation result</returns>
        public bool SendUnconnectedMessage(NetDataWriter writer, IPEndPoint remoteEndPoint)
        {
            return SendUnconnectedMessage(writer.Data, 0, writer.Length, remoteEndPoint);
        }

        /// <summary>
        /// Send message without connection
        /// </summary>
        /// <param name="message">Raw data</param>
        /// <param name="start">data start</param>
        /// <param name="length">data length</param>
        /// <param name="remoteEndPoint">Packet destination</param>
        /// <returns>Operation result</returns>
        public bool SendUnconnectedMessage(byte[] message, int start, int length, IPEndPoint remoteEndPoint)
        {
            //No need for CRC here, SendRaw does that
            NetPacket packet = PoolGetWithData(PacketProperty.UnconnectedMessage, message, start, length);
            return SendRawAndRecycle(packet, remoteEndPoint) > 0;
        }

        /// <summary>
        /// Triggers update and send logic immediately (works asynchronously)
        /// </summary>
        public void TriggerUpdate()
        {
            _updateTriggerEvent.Set();
        }

        /// <summary>
        /// Receive all pending events. Call this in game update code
        /// In Manual mode it will call also socket Receive (which can be slow)
        /// </summary>
        public void PollEvents()
        {
            if (_manualMode)
            {
                if (_udpSocketv4 != null)
                    ManualReceive(_udpSocketv4, _bufferEndPointv4);
                if (_udpSocketv6 != null && _udpSocketv6 != _udpSocketv4)
                    ManualReceive(_udpSocketv6, _bufferEndPointv6);
                ProcessDelayedPackets();
                return;
            }
            if (UnsyncedEvents)
                return;
            NetEvent pendingEvent;
            lock (_eventLock)
            {
                pendingEvent = _pendingEventHead;
                _pendingEventHead = null;
                _pendingEventTail = null;
            }

            while (pendingEvent != null)
            {
                var next = pendingEvent.Next;
                ProcessEvent(pendingEvent);
                pendingEvent = next;
            }
        }

        /// <summary>
        /// Connect to remote host
        /// </summary>
        /// <param name="address">Server IP or hostname</param>
        /// <param name="port">Server Port</param>
        /// <param name="key">Connection key</param>
        /// <returns>New NetPeer if new connection, Old NetPeer if already connected, null peer if there is ConnectionRequest awaiting</returns>
        /// <exception cref="InvalidOperationException">Manager is not running. Call <see cref="Start()"/></exception>
        public NetPeer Connect(string address, int port, string key)
        {
            return Connect(address, port, NetDataWriter.FromString(key));
        }

        /// <summary>
        /// Connect to remote host
        /// </summary>
        /// <param name="address">Server IP or hostname</param>
        /// <param name="port">Server Port</param>
        /// <param name="connectionData">Additional data for remote peer</param>
        /// <returns>New NetPeer if new connection, Old NetPeer if already connected, null peer if there is ConnectionRequest awaiting</returns>
        /// <exception cref="InvalidOperationException">Manager is not running. Call <see cref="Start()"/></exception>
        public NetPeer Connect(string address, int port, NetDataWriter connectionData)
        {
            IPEndPoint ep;
            try
            {
                ep = NetUtils.MakeEndPoint(address, port);
            }
            catch
            {
                CreateEvent(NetEvent.EType.Disconnect, disconnectReason: DisconnectReason.UnknownHost);
                return null;
            }
            return Connect(ep, connectionData);
        }

        /// <summary>
        /// Connect to remote host
        /// </summary>
        /// <param name="target">Server end point (ip and port)</param>
        /// <param name="key">Connection key</param>
        /// <returns>New NetPeer if new connection, Old NetPeer if already connected, null peer if there is ConnectionRequest awaiting</returns>
        /// <exception cref="InvalidOperationException">Manager is not running. Call <see cref="Start()"/></exception>
        public NetPeer Connect(IPEndPoint target, string key)
        {
            return Connect(target, NetDataWriter.FromString(key));
        }

        /// <summary>
        /// Connect to remote host
        /// </summary>
        /// <param name="target">Server end point (ip and port)</param>
        /// <param name="connectionData">Additional data for remote peer</param>
        /// <returns>New NetPeer if new connection, Old NetPeer if already connected, null peer if there is ConnectionRequest awaiting</returns>
        /// <exception cref="InvalidOperationException">Manager is not running. Call <see cref="Start()"/></exception>
        public NetPeer Connect(IPEndPoint target, NetDataWriter connectionData)
        {
            if (!IsRunning)
                throw new InvalidOperationException("Client is not running");

            lock(_requestsDict)
            {
                if (_requestsDict.ContainsKey(target))
                    return null;

                byte connectionNumber = 0;
                if (TryGetPeer(target, out var peer))
                {
                    switch (peer.ConnectionState)
                    {
                        //just return already connected peer
                        case ConnectionState.Connected:
                        case ConnectionState.Outgoing:
                            return peer;
                    }
                    //else reconnect
                    connectionNumber = (byte)((peer.ConnectionNum + 1) % NetConstants.MaxConnectionNumber);
                    RemovePeer(peer);
                }

                //Create reliable connection
                //And send connection request
                peer = new NetPeer(this, target, GetNextPeerId(), connectionNumber, connectionData);
                AddPeer(peer);
                return peer;
            }
        }

        /// <summary>
        /// Force closes connection and stop all threads.
        /// </summary>
        public void Stop()
        {
            Stop(true);
        }

        /// <summary>
        /// Force closes connection and stop all threads.
        /// </summary>
        /// <param name="sendDisconnectMessages">Send disconnect messages</param>
        public void Stop(bool sendDisconnectMessages)
        {
            if (!IsRunning)
                return;
            NetDebug.Write("[NM] Stop");

#if UNITY_2018_3_OR_NEWER
            _pausedSocketFix.Deinitialize();
            _pausedSocketFix = null;
#endif

            //Send last disconnect
            for(var netPeer = _headPeer; netPeer != null; netPeer = netPeer.NextPeer)
                netPeer.Shutdown(null, 0, 0, !sendDisconnectMessages);

            //Stop
            CloseSocket();
            _updateTriggerEvent.Set();
            if (!_manualMode)
            {
                _logicThread.Join();
                _logicThread = null;
            }

            //clear peers
            ClearPeerSet();
            _peerIds = new ConcurrentQueue<int>();
            _lastPeerId = 0;
#if DEBUG
            lock (_pingSimulationList)
                _pingSimulationList.Clear();
#endif
            _connectedPeersCount = 0;
            _pendingEventHead = null;
            _pendingEventTail = null;
        }

        /// <summary>
        /// Return peers count with connection state
        /// </summary>
        /// <param name="peerState">peer connection state (you can use as bit flags)</param>
        /// <returns>peers count</returns>
        public int GetPeersCount(ConnectionState peerState)
        {
            int count = 0;
            _peersLock.EnterReadLock();
            for (var netPeer = _headPeer; netPeer != null; netPeer = netPeer.NextPeer)
            {
                if ((netPeer.ConnectionState & peerState) != 0)
                    count++;
            }
            _peersLock.ExitReadLock();
            return count;
        }

        /// <summary>
        /// Get copy of peers (without allocations)
        /// </summary>
        /// <param name="peers">List that will contain result</param>
        /// <param name="peerState">State of peers</param>
        public void GetPeersNonAlloc(List<NetPeer> peers, ConnectionState peerState)
        {
            peers.Clear();
            _peersLock.EnterReadLock();
            for (var netPeer = _headPeer; netPeer != null; netPeer = netPeer.NextPeer)
            {
                if ((netPeer.ConnectionState & peerState) != 0)
                    peers.Add(netPeer);
            }
            _peersLock.ExitReadLock();
        }

        /// <summary>
        /// Disconnect all peers without any additional data
        /// </summary>
        public void DisconnectAll()
        {
            DisconnectAll(null, 0, 0);
        }

        /// <summary>
        /// Disconnect all peers with shutdown message
        /// </summary>
        /// <param name="data">Data to send (must be less or equal MTU)</param>
        /// <param name="start">Data start</param>
        /// <param name="count">Data count</param>
        public void DisconnectAll(byte[] data, int start, int count)
        {
            //Send disconnect packets
            _peersLock.EnterReadLock();
            for (var netPeer = _headPeer; netPeer != null; netPeer = netPeer.NextPeer)
            {
                DisconnectPeer(
                    netPeer,
                    DisconnectReason.DisconnectPeerCalled,
                    0,
                    false,
                    data,
                    start,
                    count,
                    null);
            }
            _peersLock.ExitReadLock();
        }

        /// <summary>
        /// Immediately disconnect peer from server without additional data
        /// </summary>
        /// <param name="peer">peer to disconnect</param>
        public void DisconnectPeerForce(NetPeer peer)
        {
            DisconnectPeerForce(peer, DisconnectReason.DisconnectPeerCalled, 0, null);
        }

        /// <summary>
        /// Disconnect peer from server
        /// </summary>
        /// <param name="peer">peer to disconnect</param>
        public void DisconnectPeer(NetPeer peer)
        {
            DisconnectPeer(peer, null, 0, 0);
        }

        /// <summary>
        /// Disconnect peer from server and send additional data (Size must be less or equal MTU - 8)
        /// </summary>
        /// <param name="peer">peer to disconnect</param>
        /// <param name="data">additional data</param>
        public void DisconnectPeer(NetPeer peer, byte[] data)
        {
            DisconnectPeer(peer, data, 0, data.Length);
        }

        /// <summary>
        /// Disconnect peer from server and send additional data (Size must be less or equal MTU - 8)
        /// </summary>
        /// <param name="peer">peer to disconnect</param>
        /// <param name="writer">additional data</param>
        public void DisconnectPeer(NetPeer peer, NetDataWriter writer)
        {
            DisconnectPeer(peer, writer.Data, 0, writer.Length);
        }

        /// <summary>
        /// Disconnect peer from server and send additional data (Size must be less or equal MTU - 8)
        /// </summary>
        /// <param name="peer">peer to disconnect</param>
        /// <param name="data">additional data</param>
        /// <param name="start">data start</param>
        /// <param name="count">data length</param>
        public void DisconnectPeer(NetPeer peer, byte[] data, int start, int count)
        {
            DisconnectPeer(
                peer,
                DisconnectReason.DisconnectPeerCalled,
                0,
                false,
                data,
                start,
                count,
                null);
        }

        /// <summary>
        /// Create the requests for NTP server
        /// </summary>
        /// <param name="endPoint">NTP Server address.</param>
        public void CreateNtpRequest(IPEndPoint endPoint)
        {
            _ntpRequests.TryAdd(endPoint, new NtpRequest(endPoint));
        }

        /// <summary>
        /// Create the requests for NTP server
        /// </summary>
        /// <param name="ntpServerAddress">NTP Server address.</param>
        /// <param name="port">port</param>
        public void CreateNtpRequest(string ntpServerAddress, int port)
        {
            IPEndPoint endPoint = NetUtils.MakeEndPoint(ntpServerAddress, port);
            _ntpRequests.TryAdd(endPoint, new NtpRequest(endPoint));
        }

        /// <summary>
        /// Create the requests for NTP server (default port)
        /// </summary>
        /// <param name="ntpServerAddress">NTP Server address.</param>
        public void CreateNtpRequest(string ntpServerAddress)
        {
            IPEndPoint endPoint = NetUtils.MakeEndPoint(ntpServerAddress, NtpRequest.DefaultPort);
            _ntpRequests.TryAdd(endPoint, new NtpRequest(endPoint));
        }

        public NetPeerEnumerator GetEnumerator()
        {
            return new NetPeerEnumerator(_headPeer);
        }

        IEnumerator<NetPeer> IEnumerable<NetPeer>.GetEnumerator()
        {
            return new NetPeerEnumerator(_headPeer);
        }

        IEnumerator IEnumerable.GetEnumerator()
        {
            return new NetPeerEnumerator(_headPeer);
        }
    }
}