//
//  Class:			AIS_Telnet
//	Current CLR:	4.0.30319.296
//	System:			Microsoft Visual Studio 10.0
//	Author:			dani
// 	Created:		3/16/2013 12:58:03 PM
//
//	Copyright (c) 2013 Informatikbüro Daniel Schick. All rights reserved.

using System;
using System.Collections.Generic;
using System.IO;
using System.Text;
using System.Net.Sockets;

using log4net;

namespace bsmd.AISService.AIS
{
    public class AIS_Telnet
    {

        #region private fields

        private const int BFSIZE = 1024;

        private NetworkStream tcpStream;
        private TcpClient tcpSocket;
        private string currentString = "";
        private string hostname;
        private int port;
        private DateTime? lastRead;

        private static ILog _log = LogManager.GetLogger(typeof(AIS_Telnet));

        #endregion

        public AIS_Telnet(string theHostname, int thePort)
        {
            this.port = thePort;
            this.hostname = theHostname;
            this.Connect();            
        }

        #region Properties

        public bool IsConnected
        {
            get { return tcpSocket.Connected; }
        }

        public string Hostname { get { return this.hostname; } }

        public int Port { get { return this.port; } }

        public string StationName { get; set; }

        #endregion

        #region public methods

        private string ReadCurrentUptoNewline()
        {
            int newlineIndex = currentString.IndexOf('\n');
            string result = this.currentString.Substring(0, newlineIndex);
            if (currentString.Length > (newlineIndex + 1))
                currentString = currentString.Substring(newlineIndex + 1);
            else
                currentString = "";
            return result;
        }

        public string ReadLine()
        {

            string result = "";
            if (currentString.IndexOf('\n') >= 0)
                return ReadCurrentUptoNewline();


            byte[] inputBuffer = new byte[1024];

            if ((tcpSocket == null) || (!tcpSocket.Connected) || !this.tcpStream.CanRead)
                this.Connect();
            if ((tcpSocket == null) || !tcpSocket.Connected)
            {
                System.Threading.Thread.Sleep(30000); // wait 5 mins if connect is unsuccessful
                return result;
            }
            if (this.tcpStream.DataAvailable)
            {
                try
                {
                    int bytesRead = this.tcpStream.Read(inputBuffer, 0, 1024);
                    if (bytesRead > 0)
                    {
                        this.lastRead = DateTime.Now;
                        this.currentString += Encoding.ASCII.GetString(inputBuffer, 0, bytesRead);
                        if (currentString.IndexOf('\n') >= 0)
                            return ReadCurrentUptoNewline();
                        if (this.currentString.Length > 1024) this.currentString = ""; // truncate to avoid overflow for wrong client data flow
                    }
                }
                catch (Exception ex)
                {
                    _log.ErrorFormat("exception reading from tcp stream: {0}", ex.Message);
                    result = "";
                }
            }
            else
            {
                // wenn die Verbindung wegkracht ist immer noch connected true, aber DataAvailable false
                // es gibt anscheinend keinen richtig guten Workaround. Hard case: Nach einer Stunde Inaktivität schließt der Client hier die
                // Verbindung und versucht reconnects. Das bekommt der LS100PortProxy aber nicht immer mit.. Folge sind dann die "stehengebliebenen"
                // Verbindungen
                if (lastRead == null) lastRead = DateTime.Now;
                if ((DateTime.Now - lastRead.Value).TotalSeconds > 600)
                {
                    this.tcpSocket.Close();
                    this.tcpSocket = null;
                    _log.Info("closing inactive TcpClient");
                    this.lastRead = DateTime.Now; // reset timer
                }

                System.Threading.Thread.Sleep(250); // wait a bit
            }

            return result;
        }

        public void Close()
        {
            if (this.tcpStream != null) this.tcpStream.Close();
            this.tcpSocket.Close();    
            this.tcpStream.Dispose();
        }

        #endregion                

        public void Connect()
        {
            try
            {
                if ((this.tcpSocket != null) && (this.tcpSocket.Connected)) return;
                this.tcpSocket = new TcpClient(this.hostname, this.port);
                this.tcpStream = tcpSocket.GetStream();                             
                _log.InfoFormat("TCP stream connected ({0}:{1})", this.hostname, this.port);
            }
            catch (Exception ex)
            {                
                _log.WarnFormat("AIS_Telnet: cannot connect to ({0}:{1}) : {2}", this.hostname, this.port, ex.Message);
            }
        }
    }
}