/* Copyright (c) 2010 Michael Lidgren

Permission is hereby granted, free of charge, to any person obtaining a copy of this software
and associated documentation files (the "Software"), to deal in the Software without
restriction, including without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom
the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or
substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Net;
using System.Text;

namespace Lidgren.Network
{
	[DebuggerDisplay("LengthBits={LengthBits}")]
	public sealed partial class NetOutgoingMessage
	{
		// reference count before message can be recycled
		internal int m_inQueueCount;

		internal NetMessageType m_type;
		internal NetMessageLibraryType m_libType;

		internal IPEndPoint m_unconnectedRecipient;

		internal double m_lastSentTime; // when was this message sent last?
		internal double m_nextResendTime; // when to resend this message the next time
		internal int m_numSends; // the number of times this message has been sent/resent

		internal int m_fragmentGroupId;
		internal int m_fragmentNumber;
		internal int m_fragmentTotalCount;

		/// <summary>
		/// Returns true if this message has been passed to SendMessage() already
		/// </summary>
		public bool IsSent { get { return m_numSends > 0; } }

		internal NetOutgoingMessage()
		{
			Reset();
		}

		internal void Reset()
		{
			NetException.Assert(m_inQueueCount == 0, "Ouch! Resetting NetOutgoingMessage still in some queue!");

			m_bitLength = 0;
			m_type = NetMessageType.Error;
			m_inQueueCount = 0;
			m_numSends = 0;
			m_fragmentGroupId = -1;
		}

		internal static int EncodeAcksMessage(byte[] buffer, int ptr, NetConnection conn, int maxBytesPayload)
		{
			// TODO: if appropriate; make bit vector of adjacent acks

			buffer[ptr++] = (byte)NetMessageType.Library;
			buffer[ptr++] = (byte)NetMessageLibraryType.Acknowledge;

			Queue<int> acks = conn.m_acknowledgesToSend;

			int maxAcks = maxBytesPayload / 3;
			int acksToEncode = (acks.Count < maxAcks ? acks.Count : maxAcks);

			int payloadBitsLength = acksToEncode * 3 * 8;
			if (payloadBitsLength < 127)
			{
				buffer[ptr++] = (byte)payloadBitsLength;
			}
			else
			{
				buffer[ptr++] = (byte)((payloadBitsLength & 127) | 128);
				buffer[ptr++] = (byte)(payloadBitsLength >> 7);
			}

			for (int i = 0; i < acksToEncode; i++)
			{
				int ack = acks.Dequeue();
				buffer[ptr++] = (byte)ack; // message type
				buffer[ptr++] = (byte)(ack >> 8); // seqnr low
				buffer[ptr++] = (byte)(ack >> 16); // seqnr high
			}

			return ptr;
		}

		// encode and store for resending (if conn != null and message is reliable)
		internal int Encode(double now, byte[] buffer, int ptr, NetConnection conn)
		{
			// message type
			buffer[ptr++] = (byte)((int)m_type | (m_fragmentGroupId == -1 ? 0 : 128));

			if (m_type == NetMessageType.Library)
				buffer[ptr++] =(byte)m_libType;

			// channel sequence number
			if (m_type >= NetMessageType.UserSequenced)
			{
				if (conn == null)
					throw new NetException("Trying to encode NetMessageType " + m_type + " to unconnected endpoint!");
				
				ushort seqNr;
				if (m_type < NetMessageType.UserReliableUnordered)
					seqNr = conn.GetSendSequenceNumber(m_type); // "disposable" sequence number
				else
					seqNr = conn.StoreReliableMessage(now, this);

				buffer[ptr++] = (byte)seqNr;
				buffer[ptr++] = (byte)(seqNr >> 8);
			}

			// payload length
			int payloadBitsLength = LengthBits;
			int payloadBytesLength = NetUtility.BytesToHoldBits(payloadBitsLength);
			if (payloadBitsLength < 127)
			{
				buffer[ptr++] = (byte)payloadBitsLength;
			}
			else if (payloadBitsLength < 32768)
			{
				buffer[ptr++] = (byte)((payloadBitsLength & 127) | 128);
				buffer[ptr++] = (byte)(payloadBitsLength >> 7);
			}
			else
			{
				throw new NetException("Packet content too large; 4095 bytes maximum");
			}

			// fragmentation info
			if (m_fragmentGroupId != -1)
			{
				buffer[ptr++] = (byte)m_fragmentGroupId;
				buffer[ptr++] = (byte)(m_fragmentGroupId >> 8);
				buffer[ptr++] = (byte)m_fragmentTotalCount;
				buffer[ptr++] = (byte)(m_fragmentTotalCount >> 8);
				buffer[ptr++] = (byte)m_fragmentNumber;
				buffer[ptr++] = (byte)(m_fragmentNumber >> 8);
			}

			// payload
			if (payloadBitsLength > 0)
			{
				// zero out last byte
				buffer[ptr + payloadBytesLength] = 0;

				Buffer.BlockCopy(m_data, 0, buffer, ptr, payloadBytesLength);
				ptr += payloadBytesLength;
			}

			m_numSends++;

			return ptr;
		}

		public void Encrypt(NetXtea tea)
		{
			// need blocks of 8 bytes
			WritePadBits();
			int blocksNeeded = (m_bitLength + 63) / 64;
			int missingBits = (blocksNeeded * 64) - m_bitLength;
			int missingBytes = NetUtility.BytesToHoldBits(missingBits);
			for (int i = 0; i < missingBytes; i++)
				Write((byte)0);

			byte[] result = new byte[m_data.Length];
			for(int i=0;i<blocksNeeded;i++)
				tea.EncryptBlock(m_data, (i * 8), result, (i * 8));
			m_data = result;
		}

		public override string ToString()
		{
			StringBuilder bdr = new StringBuilder();
			bdr.Append("[NetOutgoingMessage ");
			bdr.Append(m_type.ToString());
			if (m_type == NetMessageType.Library)
			{
				bdr.Append('|');
				bdr.Append(m_libType.ToString());
			}
			bdr.Append(" sent ");
			bdr.Append(m_numSends);
			bdr.Append(" times]");
			return bdr.ToString();
		}
	}
}