using System;
using System.Net;
using System.Net.Sockets;
using System.Numerics;
using System.Threading;
using System.Threading.Tasks;

namespace Mistox.Server {
    public class ServerConnection : IDisposable {
        
        public string UserName { get; set; } = "";                          // The Players UserName
        public bool IsAuthenticated { get; set; } = false;                  // Has the player authenticated
        public Vector3 Position { get; set; }                               // The ingame position of the player
        public DateTime LastHeartbeat { get; set; } = DateTime.UtcNow;      // Connection heartbeat for integrity
        public bool Connected { get; set; } = true;                         // Is the connection valid
        
        ServerEntity _parent;
        TcpClient _client;
        IPEndPoint _remoteAddress;

        public ServerConnection( TcpClient tcpClient, ServerEntity parent, IPEndPoint remote ) {
            _parent = parent;
            _client = tcpClient;
            _remoteAddress = remote;
            _client.NoDelay = true;

            ServerInterface.ServerInstance.InvokeUserConnected( this );
            // Start the receive thread
            Thread receiveThread = new Thread(async () => await ReceiveThread() );
            receiveThread.Start();
        }

        async Task ReceiveThread() {
            using( NetworkStream ns = _client.GetStream() ) {
                try {
                    byte[] headerBuffer = new byte[DataPacket.HeaderLength];    
                    byte[] payloadBuffer = new byte[65535];                     // Upper limit for safety
                    while( Connected && _parent.Alive ) {

                        // Tick the last heartbeat or drop
                        DateTime now = DateTime.UtcNow;
                        if (LastHeartbeat.AddSeconds(_parent.ConnectionTimeoutSeconds) >= now) {
                            Connected = false;
                            Dispose();
                            break;
                        }
                        LastHeartbeat = DateTime.UtcNow;
                        
                        // Read the header off
                        await ns.ReadExactlyAsync(headerBuffer, 0, 3);

                        // Parse the header
                        byte packetbyte = headerBuffer[0];
                        ushort dataLength = (ushort)((headerBuffer[1] << 8) | headerBuffer[2]);

                        // Make sure the data looks valid
                        if (dataLength > payloadBuffer.Length) {
                            throw new Exception("Incoming TCP payload is too large for the pre-allocated buffer.");
                        }

                        // Read off the data
                        await ns.ReadExactlyAsync(payloadBuffer, 0, dataLength);

                        // Create the dataobject
                        dynamic dataobject = DataPacket.Deserialize( packetbyte, dataLength, payloadBuffer.AsMemory(DataPacket.HeaderLength, dataLength) );

                        // Return the object
                        _parent.InvokeDataReceived(dataobject);

                    }
                } catch (Exception e) {
                    _parent.Alive = false;
                    Dispose();
                    Console.WriteLine("TCP Receive exception: " + e.Message);
                }
            }
        }

        public async Task Send<T>( T packet ) {
            byte[] byteData = DataPacket.Serialize( packet );
            await _client.GetStream().WriteAsync( byteData, 0, byteData.Length );
        }

        public void Dispose() {
            Connected = false;
            _parent.InvokeUserDisconnected( this );
            Connected = false;
            _parent.Alive = false;
            // Remove this item from the Dictionary on the Server for garbage collection
        }
    }
}