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using System;
using System.Collections.Generic;
using System.Linq;
using NLog;
using Raytheon.Instruments;

namespace ProgramLib
{
   /// <summary>
	/// Perform UART loopback test
	/// </summary>
   internal class UartLoopBackAction : BasicAction
   {
      #region PrivateClassMembers
      private static NLog.ILogger _logger;

      private ICommDevice _serialDevice;

      #endregion

      /// <summary>
      /// Constructor
      /// </summary>
      /// <returns></returns>
      public UartLoopBackAction()
      {
         _logger = LogManager.GetCurrentClassLogger();

         string serialDeviceInstanceName = Program.Instance().ProgramSpecificConfig.ReadValue("UART_INFO", "SERIAL_DEVICE_INSTANCE_NAME");
         _serialDevice = (ICommDevice)Program.Instance().InstrumentManager.GetGenericInstrument(serialDeviceInstanceName);
      }

      /// <summary>
      /// Run the action
      /// </summary>
      /// <returns></returns>
      public override void Run()
      {
         try
         {
            _logger?.Debug($"Entering {this.GetType().Name}::{System.Reflection.MethodBase.GetCurrentMethod().Name}() method...");

            SendCommandAndGetResponse();
         }
         catch (Exception)
         {
            throw;
         }
      }

      /// <summary>
      /// Send commnd and get response
      /// </summary>
      /// <returns></returns>
      public void SendCommandAndGetResponse()
      {
         UartHandshakeMessage msg = new UartHandshakeMessage(0xCCAAFFEEDDAAEEDD, 0xDDEEAADDEEFFAACC);
         List<byte> msgByteList = Util.StructToByteList(msg).ToList();
         // remove checksum byte
         msgByteList.RemoveAt(msgByteList.Count - 1);
         msgByteList.Add(Util.GetTwosComplimentChecksum(msgByteList.ToArray()));
         _serialDevice.Write(msgByteList.ToArray(), (uint)msgByteList.Count);
         _logger.Info($"Raw message sent: {Util.ByteArrayToHexString(msgByteList.ToArray())}");

         List<byte> receiveByteList = new List<byte>();
         byte[] receiveByteArray = null;
         uint totalBytesRead = 0;

         _logger.Info($"Waiting for message to be looped back...");

         uint numBytesRead = _serialDevice.Read(ref receiveByteArray);
         // this is for loopback, we read too fast and we're only getting partial data
         if (numBytesRead < msgByteList.Count)
         {
            _serialDevice.SetReadTimeout(100);
            try
            {
               do
               {
                  totalBytesRead += numBytesRead;
                  receiveByteList.AddRange(receiveByteArray.Skip(0).Take((int)numBytesRead).ToArray());
                  receiveByteArray = null;
                  numBytesRead = _serialDevice.Read(ref receiveByteArray);
               }
               while (true);
            }
            catch { }
            // reset to default timeout
            _serialDevice.SetReadTimeout();
            receiveByteArray = receiveByteList.ToArray();
         }
         else
            totalBytesRead = numBytesRead;

         _logger.Info($"Raw Msg Received: {Util.ByteArrayToHexString(receiveByteArray, (int)totalBytesRead)}");

         if (totalBytesRead != msgByteList.Count)
         {
            throw new Exception($"Unexpected message size. Expected msg size: {msgByteList.Count}. Actual msg size: {totalBytesRead}");
         }

         bool loopbackSuccess = true;
         for (int i = 0; i < totalBytesRead; i++)
         {
            if (msgByteList[i] != receiveByteArray[i])
            {
               loopbackSuccess = false;
               break;
            }
         }

         if (!loopbackSuccess)
         {
            throw new Exception($"Messages sent and received don't match");
         }

         _logger.Info($"UART loopback is successful.");
      }
   }
}