//                           UNCLASSIFIED
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UNPUBLISHED WORK - COPYRIGHT RAYTHEON COMPANY.
-------------------------------------------------------------------------*/

using System;
using System.Threading;
using System.Collections.Generic;

namespace Raytheon.Common
{
	/// <summary>
	/// Singleton for holding onto message objects
	/// </summary>
	public class AutomationRxMsgBuffer
	{
		// class variables
		private static AutomationRxMsgBuffer _AutomationRxMsgBufferInstance;
		private static object _syncObj = new object();
		private Dictionary<uint, List<AutomationMessage>> _msgList;
		private Dictionary<uint, AutoResetEvent> _receivedMsgEvents;
		private List<uint> _msgIds;

		/// <summary>
		/// The way to get access to this singleton
		/// </summary>
		/// <returns>the instance to this class</returns>
		public static AutomationRxMsgBuffer Instance(List<uint> msgIds = null)
		{
			if (_AutomationRxMsgBufferInstance == null)
			{
				_AutomationRxMsgBufferInstance = new AutomationRxMsgBuffer(msgIds);
			}

			return _AutomationRxMsgBufferInstance;
		}

		/// <summary>
		/// Add a message to this buffer
		/// </summary>
		/// <param name="msg">The message to add</param>
		/// <param name="shouldWeDeleteOthers">flag for if the other messages of this type should be deleted from the buffer</param>
		public void AddMsg(AutomationMessage msg, bool shouldWeDeleteOthers = true)
		{
			lock (_syncObj)
			{
				uint msgId = msg.GetMessageId();

				if (shouldWeDeleteOthers == true)
				{
					ClearList(msgId);
				}

				if (_msgList.ContainsKey(msgId) == false)
				{
					_msgList[msgId] = new List<AutomationMessage>();
				}

				_msgList[msgId].Add(msg);

				_receivedMsgEvents[msgId].Set();
			}
		}

		/// <summary>
		/// Remove all messages from the buffer
		/// </summary>
		public void ClearAllMsgs()
		{
			lock (_syncObj)
			{
				foreach (uint id in _msgList.Keys)
				{
					ClearList(id);
				}
			}
		}

		/// <summary>
		/// Remove all messages of the command type from the buffer
		/// </summary>
		/// <param name="id">The message id to remove</param>
		public void ClearList(uint id)
		{
			lock (_syncObj)
			{
				if (_msgList.ContainsKey(id) == true)
				{
					_msgList[id].Clear();

					_msgList.Remove(id);
				}
			}
		}

		/// <summary>
		/// Gets the oldest message in the buffer
		/// </summary>
		/// <param name="id">The id of the message to get</param>
		/// <returns>The oldest message in the buffer</returns>
		public AutomationMessage GetOldestMessage(uint id)
		{
			lock (_syncObj)
			{
				if (_msgList.ContainsKey(id))
				{
					List<AutomationMessage> list = _msgList[id];

					AutomationMessage oldestMsg = list[0];

					list.RemoveAt(0);

					return oldestMsg;
				}
				else
				{
					throw new Exception("no message exists with id: " + id.ToString());
				}
			}
		}

		/// <summary>
		/// Gets the most recent message from the buffer
		/// </summary>
		/// <param name="id">The id of the message to get</param>
		/// <param name="shouldWeDeleteOthers">flag controlling if the other messages of this type should be deleted</param>
		/// <returns>The message</returns>
		public AutomationMessage GetNewestMessage(uint id, bool shouldWeDeleteOthers = true)
		{
			lock (_syncObj)
			{
				if (_msgList.ContainsKey(id))
				{
					List<AutomationMessage> list = _msgList[id];

					AutomationMessage newestMsg = list[list.Count - 1];

					list.RemoveAt(list.Count - 1);

					if (shouldWeDeleteOthers == true)
					{
						ClearList(id);
					}

					return newestMsg;
				}
				else
				{
					throw new Exception("no message exists with id: " + id.ToString());
				}
			}
		}

		/// <summary>
		/// Get the number of messages of this type in the buffer
		/// </summary>
		/// <param name="id">The id of the message to get</param>
		/// <returns>the number of messages of this type in the buffer</returns>
		public int GetNumMsgsInQueue(uint id)
		{
			lock (_syncObj)
			{
				if (_msgList.ContainsKey(id) == true)
				{
					return _msgList[id].Count;
				}
				else
				{
					return 0;
				}
			}
		}

		/// <summary>
		/// 
		/// </summary>
		/// <param name="id"></param>
		public void ResetRxEvent(uint id)
		{
			lock (_syncObj)
			{
				_receivedMsgEvents[id].Reset();
			}
		}

		/// <summary>
		/// Wait for a message to get added to the buffer
		/// </summary>
		/// <param name="id">The message id to wait for</param>
		/// <param name="timeoutMs">The amount of time in ms to wait</param>
		/// <returns>true if the message arrived, false if it did not</returns>
		public bool WaitForRspMsg(uint id, int timeoutMs)
		{
			return _receivedMsgEvents[id].WaitOne(timeoutMs);
		}

		/// <summary>
		/// The constructor
		/// </summary>
		private AutomationRxMsgBuffer(List<uint> msgIds)
		{
			_msgList = new Dictionary<uint, List<AutomationMessage>>();

			_msgIds = msgIds;

			// create an event for each msg.
			_receivedMsgEvents = new Dictionary<uint, AutoResetEvent>();

			foreach (uint id in _msgIds)
			{
				_receivedMsgEvents[id] = new AutoResetEvent(false);
			}
		}
	}
}