///
/// Copyright (c) 2018 Sensus Slovensko a.s.
///
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Globalization;
using System.IO.Ports;
using System.Text;
using System.Threading;
using Common;
using Config.Entities;
using log4net;
using TBF.Rig.Generic;
using TBF.Boxes;

namespace TBF.Rig.Hart.Common
{
    /// <summary>
	/// Root component for HART communication via a modem connected to a serial port (RS232)
	/// </summary>
	public class Hart : ComponentBase, IDevice, GenericDevices.IHart
    {
		private static readonly ILog log = LogManager.GetLogger(typeof(Hart));
		public override string ToString() { return string.Format("Modbus({0})", Cfg.ToString(1)); }

		private readonly HartCfg hartCfg;

		/// Private fields
		SerialPort serialPort;
        DateTime lastSerialPortWrite;

		/// <summary>
		/// An array of Queue-s of received telegrams fetched by HART components (as Nivotrack).
		/// There is one queue for each device (each slave address).
		/// </summary>
		public Queue<byte[]>[] ReceivedTelegrams
		{
			get { return receivedTelegrams; }
		}
		Queue<byte[]>[] receivedTelegrams;

		/// <summary>
		/// A Queue of telegrams to send. System prevents sending more then one telegram per 500ms.
		/// Function SendMessage( ) either send the telegram immediately using SendMessageNow( ) or
		/// inserts the telegram into telegramsToSend queue. The queue is emptied in RunDeviceAfter( ).
		/// </summary>
        Queue<byte[]> telegramsToSend;


		public Hart()
		{
		}

		/// <summary>
		/// HART modem connected via serial interface (RS232).
		/// Connection settings: 1200 Bd 8-bits odd-parity 1-stop-bit Flow control: none or hardware.
		/// </summary>
		public Hart(Generic.IComponentCfg cfg)
            : base(cfg)
        {
			receivedTelegrams = new Queue<byte[]>[16];		/// Max. 16 slaves with adresses 0..15
			for (int i = 0; i < receivedTelegrams.Length; i++)
			{
				receivedTelegrams[i] = new Queue<byte[]>();
			}
            telegramsToSend = new Queue<byte[]>();

			serialPort = null;
			hartCfg = cfg as HartCfg;
            log.Warn(this.ToString());
		}

		~Hart()
		{
		}


		public void Initialize()
		{
			if (hartCfg.DebugLevel == DebugMode.Simulate)
			{
				serialPort = null;
				log.FatalFormat("{0} - Device simulated", Name);
				return;
			}

			string comPortName = "COM" + hartCfg.ComPortNr.ToString();
			serialPort = new SerialPort(comPortName, hartCfg.BaudRate, hartCfg.Parity, hartCfg.DataBits, hartCfg.StopBits);
			serialPort.Handshake = hartCfg.Handshake;
			serialPort.Open();

            log.FatalFormat("{0} - Device successfully initialized", Name);
		}

		public void RunDeviceBefore()
		{
			if (serialPort != null)
			{
				ParseReceivedData();
			}
		}

		public void RunDeviceAfter()
		{
			if ((serialPort != null) && (telegramsToSend.Count > 0) && (DateTime.Now - lastSerialPortWrite) > new TimeSpan(0, 0, 0, 0, 500))
			{
				SendMessageNow(telegramsToSend.Dequeue());
			}
		}

		public void StopDevice()
		{
			if (serialPort != null)
			{
				serialPort.Close();
				serialPort = null;
			}
		}

		public void StopDevice2() { }



		public void SendMessageNow(byte[] message)
		{
			serialPort.Write(message, 0, message.Length);
			lastSerialPortWrite = DateTime.Now;

			string s = Telegram.LogTelegram(string.Format("{0} - Sending message ", Name), message);
			Debug.WriteLine(s);
			log.Debug(s);
		}

		/// <summary>
		/// Send an arbitrary modbus message.
		/// When the message length is N, however only bytes 1..N-2 have to be set.
		/// The last two message bytes (CRC) may be uninitialized or zero.
		/// They are calculated inside this function as required by Modbus specification.
		/// </summary>
		/// <param name="message">Message incl. a reserved checksum byte, checksum does not have to be set</param>
		public void SendMessage(int preambLen, byte[] message)
		{
			if (serialPort == null) return;

			Telegram.UpdateTelegramChecksum(message);
			byte[] preambAndMessage = new byte[message.Length + preambLen];

			for (int i = 0; i < preambLen; i++) preambAndMessage[i] = (byte)0xFF;
			for (int i = preambLen; i < preambLen + message.Length; i++) preambAndMessage[i] = message[i - preambLen];

            if ((DateTime.Now - lastSerialPortWrite) > new TimeSpan(0, 0, 0, 0, 500))
            {
                /// More then 100 ms since last 'send' --> do not enqueue the message
                SendMessageNow(preambAndMessage);
            }
            else
            {
                telegramsToSend.Enqueue(preambAndMessage);

                string s = Telegram.LogTelegram(string.Format("{0} - Enqueueing message ", Name), message);
                Debug.WriteLine(s);
                log.Debug(s);
            }
        }

		void ParseReceivedData()
		{
			int nrBytes = serialPort.BytesToRead;
			if (nrBytes > 0)
			{
				/// Read available data
				byte[] buf = new byte[nrBytes];
				serialPort.Read(buf, 0, nrBytes);

				/// Determine count of leading FF-s
				int preambLen = 0;
				for (int i = 0; i < nrBytes; i++)
				{
					if (buf[i] != (byte)0xFF) break;
					preambLen++;
				}

				int telegramLen = nrBytes - preambLen;

				/// Check a telegram length, a checksum, a start byte (S -> M) and a master address (primary)
				if (preambLen < 3 ||
					telegramLen < 4 ||
					!Telegram.VerifyTelegramChecksum(preambLen, buf) ||
					((buf[preambLen] != (byte)Mark.ShortFrameSlave2Master) && (buf[preambLen] != (byte)Mark.LongFrameSlave2Master)) ||
					((buf[preambLen + 1] & 0x80) != (byte)Master.Primary))
				{
					string s = Telegram.LogTelegram(string.Format("{0} - Invalid data received ", Name), buf);
					Debug.WriteLine(s);
					log.Debug(s);
					return;
				}

				/// Strip the preamble
				byte[] data = new byte[telegramLen];
				for (int i = preambLen; i < nrBytes; i++) data[i - preambLen] = buf[i];

				bool isShortFrame = (data[0] == 0x06);

				if (isShortFrame)		
				{
					int address = data[1] & 0x0F;
					receivedTelegrams[address].Enqueue(data);

					string s = string.Format("{0} - {1} address={2} preambLen={3} count={4}", Name, Telegram.LogTelegram("Valid telegram received: ", data), address, preambLen, receivedTelegrams[address].Count);
					Debug.WriteLine(s);
					log.Debug(s);
				}
				else
				{
					/// TODO
					string s = Telegram.LogTelegram(string.Format("{0} - Telegram with long address received ", Name), buf);
					Debug.WriteLine(s);
					log.Debug(s);
				}
			}
		}
	}
}