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

namespace Tango.Transport.Servers
{
    /// <summary>
    /// Represents a TCP/IP listener wrapper.
    /// </summary>
    public class TcpServer
    {
        private LogManager LogManager = LogManager.Default;

        /// <summary>
        /// The TcpListener that is encapsulated behind this Server instance.
        /// </summary>
        public TcpListener Listener { get; set; }
        /// <summary>
        /// The Port that is used to listen to incoming connections.
        /// </summary>
        public int Port { get; set; }
        /// <summary>
        /// Returns true if the Server instance is running.
        /// </summary>
        public bool IsStarted { get; private set; }

        #region Events

        public event EventHandler<ClientConnectedEventArgs> ClientConnected;

        #endregion

        #region Constructors

        /// <summary>
        /// Initializes a new Server instance.
        /// </summary>
        /// <param name="port">The port number that is used to listen for incoming connections.</param>
        public TcpServer(int port)
        {
            Port = port;
        }
        #endregion

        #region Public Methods

        /// <summary>
        /// Start Listening for incoming connections.
        /// </summary>
        public void Start()
        {
            if (!IsStarted)
            {
                Listener = new TcpListener(System.Net.IPAddress.Any, Port);
                Listener.ExclusiveAddressUse = false;
                Listener.Server.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
                Listener.Start();
                IsStarted = true;
                LogManager.Log($"TCP server started on port {Port}.");
                WaitForConnection();
            }
        }
        /// <summary>
        /// Stop listening for incoming connections.
        /// </summary>
        public void Stop()
        {
            if (IsStarted)
            {
                Listener.Stop();
                IsStarted = false;
                LogManager.Log($"TCP server stopped on port {Port}.");
            }
        }

        #endregion

        #region Incoming Connections Methods

        private void WaitForConnection()
        {
            Listener.BeginAcceptTcpClient(new AsyncCallback(ConnectionHandler), null);
        }

        private void ConnectionHandler(IAsyncResult ar)
        {
            if (IsStarted)
            {
                try
                {
                    OnClientConnected(Listener.EndAcceptTcpClient(ar));
                    WaitForConnection();
                }
#pragma warning disable CS0168 // Variable is declared but never used
                catch (ObjectDisposedException ex)
#pragma warning restore CS0168 // Variable is declared but never used
                {
                    //Ignore..
                }
            }
        }

        #endregion

        #region Virtual Methods

        protected virtual void OnClientConnected(TcpClient socket)
        {
            ClientConnected?.Invoke(this, new ClientConnectedEventArgs(socket));
        }

        #endregion
    }
}