/**********************************************************************
 * Copyright (c) 2010, j. montgomery                                  *
 * All rights reserved.                                               *
 *                                                                    *
 * Redistribution and use in source and binary forms, with or without *
 * modification, are permitted provided that the following conditions *
 * are met:                                                           *
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 *   notice, this list of conditions and the following disclaimer.    *
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 * + Redistributions in binary form must reproduce the above copyright*
 *   notice, this list of conditions and the following disclaimer     *
 *   in the documentation and/or other materials provided with the    *
 *   distribution.                                                    *
 *                                                                    *
 * + Neither the name of j. montgomery's employer nor the names of    *
 *   its contributors may be used to endorse or promote products      *
 *   derived from this software without specific prior written        *
 *   permission.                                                      *
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 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS*
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 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED*
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 **********************************************************************/
using System;
using System.Collections.Generic;
using System.IO;
using System.Net;
using System.Net.Sockets;
using DnDns.Records;

using DnDns.Enums;

namespace DnDns.Query
{
	/// <summary>
	/// Summary description for DnsQueryResponse.
	/// </summary>
	public class DnsQueryResponse : DnsQueryBase
    {
        #region Fields
        private DnsQueryRequest _queryRequest = new DnsQueryRequest();

        private IDnsRecord[] _answers;
        private IDnsRecord[] _authoritiveNameServers;
	    private int _bytesReceived = 0;
        #endregion Fields

        #region properties
        public DnsQueryRequest QueryRequest
        {
            get { return _queryRequest; }
        }

        public IDnsRecord[] Answers
        {
            get { return _answers; }
        }

        public IDnsRecord[] AuthoritiveNameServers
        {
            get { return _authoritiveNameServers; }
        }

	    public int BytesReceived
        {
            get { return _bytesReceived; }
        }
        #endregion

        /// <summary>
        /// 
        /// </summary>
		public DnsQueryResponse() 
		{
		}
		
		private DnsQueryRequest ParseQuery(ref MemoryStream ms) 
		{
			DnsQueryRequest queryRequest = new DnsQueryRequest();
			
            // Read name
            queryRequest.Name = DnsRecordBase.ParseName(ref ms);

			return queryRequest;
		}

		internal void ParseResponse(byte[] recvBytes, ProtocolType protocol)
		{
			MemoryStream memoryStream = new MemoryStream(recvBytes);
            byte[] flagBytes = new byte[2];
            byte[] transactionId = new byte[2];
			byte[] questions = new byte[2];
			byte[] answerRRs = new byte[2];
			byte[] authorityRRs = new byte[2];
			byte[] additionalRRCountBytes = new byte[2];
            byte[] nsType = new byte[2];
            byte[] nsClass = new byte[2];

			this._bytesReceived = recvBytes.Length;

			// Parse DNS Response
			memoryStream.Read(transactionId, 0, 2);
            memoryStream.Read(flagBytes, 0, 2);
			memoryStream.Read(questions, 0, 2);
			memoryStream.Read(answerRRs, 0, 2);
			memoryStream.Read(authorityRRs, 0, 2);
            memoryStream.Read(additionalRRCountBytes, 0, 2);

            // Parse Header
            _transactionId = (ushort)IPAddress.NetworkToHostOrder((short)BitConverter.ToUInt16(transactionId, 0));
            _flags = (ushort)IPAddress.NetworkToHostOrder((short)BitConverter.ToUInt16(flagBytes, 0));
            _queryResponse = (QueryResponse)(_flags & (ushort)FlagMasks.QueryResponseMask);
            _opCode = (OpCode)(_flags & (ushort)FlagMasks.OpCodeMask);
            _nsFlags = (NsFlags)(_flags & (ushort)FlagMasks.NsFlagMask);
            _rCode = (RCode)(_flags & (ushort)FlagMasks.RCodeMask);

            // Parse Questions Section
            _questions = (ushort)IPAddress.NetworkToHostOrder((short)BitConverter.ToUInt16(questions, 0));
            _answerRRs = (ushort)IPAddress.NetworkToHostOrder(BitConverter.ToInt16(answerRRs, 0));
            _authorityRRs = (ushort)IPAddress.NetworkToHostOrder(BitConverter.ToInt16(authorityRRs, 0));
            ushort additionalRRCount = (ushort)IPAddress.NetworkToHostOrder(BitConverter.ToInt16(additionalRRCountBytes, 0));
            _additionalRecords = new List<IDnsRecord>();
            _answers = new DnsRecordBase[_answerRRs];
            _authoritiveNameServers = new DnsRecordBase[_authorityRRs];
			
			// Parse Queries
			_queryRequest = this.ParseQuery(ref memoryStream);

            // Read dnsType
            memoryStream.Read(nsType, 0, 2);

            // Read dnsClass
            memoryStream.Read(nsClass, 0, 2);

            _nsType = (NsType)IPAddress.NetworkToHostOrder(BitConverter.ToInt16(nsType, 0));
            _nsClass = (NsClass)IPAddress.NetworkToHostOrder(BitConverter.ToInt16(nsClass, 0));

			// Read in Answer Blocks
			for (int i=0; i < _answerRRs; i++)
			{
				_answers[i] = RecordFactory.Create(ref memoryStream);
			}

			// Parse Authority Records
			for (int i=0; i < _authorityRRs; i++) 
			{
                _authoritiveNameServers[i] = RecordFactory.Create(ref memoryStream);
			}

			// Parse Additional Records
			for (int i=0; i < additionalRRCount; i++) 
			{
                _additionalRecords.Add(RecordFactory.Create(ref memoryStream));
			}
		}
	}
}