/*
===========================================================================

Return to Castle Wolfenstein single player GPL Source Code
Copyright (C) 1999-2010 id Software LLC, a ZeniMax Media company. 

This file is part of the Return to Castle Wolfenstein single player GPL Source Code (RTCW SP Source Code).  

RTCW SP Source Code is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

RTCW SP Source Code is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with RTCW SP Source Code.  If not, see <http://www.gnu.org/licenses/>.

In addition, the RTCW SP Source Code is also subject to certain additional terms. You should have received a copy of these additional terms immediately following the terms and conditions of the GNU General Public License which accompanied the RTCW SP Source Code.  If not, please request a copy in writing from id Software at the address below.

If you have questions concerning this license or the applicable additional terms, you may contact in writing id Software LLC, c/o ZeniMax Media Inc., Suite 120, Rockville, Maryland 20850 USA.

===========================================================================
*/


#include "../qcommon/q_shared.h"
#include "../qcommon/qcommon.h"
#include "client.h"

#ifdef LEGACY_PROTOCOL
/*
==============
CL_Netchan_Encode

	// first 12 bytes of the data are always:
	long serverId;
	long messageAcknowledge;
	long reliableAcknowledge;

==============
*/
static void CL_Netchan_Encode( msg_t *msg ) {
	int serverId, messageAcknowledge, reliableAcknowledge;
	int i, index, srdc, sbit, soob;
	byte key, *string;

	if ( msg->cursize <= CL_ENCODE_START ) {
		return;
	}

	srdc = msg->readcount;
	sbit = msg->bit;
	soob = msg->oob;

	msg->bit = 0;
	msg->readcount = 0;
	msg->oob = 0;

	serverId = MSG_ReadLong( msg );
	messageAcknowledge = MSG_ReadLong( msg );
	reliableAcknowledge = MSG_ReadLong( msg );

	msg->oob = soob;
	msg->bit = sbit;
	msg->readcount = srdc;

	string = (byte *)clc.serverCommands[ reliableAcknowledge & ( MAX_RELIABLE_COMMANDS - 1 ) ];
	index = 0;
	//
	key = clc.challenge ^ serverId ^ messageAcknowledge;
	for ( i = CL_ENCODE_START; i < msg->cursize; i++ ) {
		// modify the key with the last received now acknowledged server command
		if ( !string[index] ) {
			index = 0;
		}
		if ( string[index] > 127 || string[index] == '%' ) {
			key ^= '.' << ( i & 1 );
		} else {
			key ^= string[index] << ( i & 1 );
		}
		index++;
		// encode the data with this key
		*( msg->data + i ) = ( *( msg->data + i ) ) ^ key;
	}
}

/*
==============
CL_Netchan_Decode

	// first four bytes of the data are always:
	long reliableAcknowledge;

==============
*/
static void CL_Netchan_Decode( msg_t *msg ) {
	long reliableAcknowledge, i, index;
	byte key, *string;
	int srdc, sbit, soob;

	srdc = msg->readcount;
	sbit = msg->bit;
	soob = msg->oob;

	msg->oob = 0;

	reliableAcknowledge = MSG_ReadLong( msg );

	msg->oob = soob;
	msg->bit = sbit;
	msg->readcount = srdc;

	string = (byte *) clc.reliableCommands[ reliableAcknowledge & (MAX_RELIABLE_COMMANDS-1) ];
	index = 0;
	// xor the client challenge with the netchan sequence number (need something that changes every message)
	key = clc.challenge ^ LittleLong( *(unsigned *)msg->data );
	for ( i = msg->readcount + CL_DECODE_START; i < msg->cursize; i++ ) {
		// modify the key with the last sent and with this message acknowledged client command
		if ( !string[index] ) {
			index = 0;
		}
		if ( string[index] > 127 || string[index] == '%' ) {
			key ^= '.' << ( i & 1 );
		} else {
			key ^= string[index] << ( i & 1 );
		}
		index++;
		// decode the data with this key
		*( msg->data + i ) = *( msg->data + i ) ^ key;
	}
}
#endif

/*
=================
CL_Netchan_TransmitNextFragment
=================
*/
qboolean CL_Netchan_TransmitNextFragment(netchan_t *chan)
{
	if(chan->unsentFragments)
	{
		Netchan_TransmitNextFragment(chan);
		return qtrue;
	}
	
	return qfalse;
}

/*
================
CL_Netchan_Transmit
================
*/
void CL_Netchan_Transmit( netchan_t *chan, msg_t* msg ) {
	MSG_WriteByte( msg, clc_EOF );

#ifdef LEGACY_PROTOCOL
	if(chan->compat)
		CL_Netchan_Encode(msg);
#endif

	Netchan_Transmit(chan, msg->cursize, msg->data);
	
	// Transmit all fragments without delay
	while(CL_Netchan_TransmitNextFragment(chan))
	{
		Com_DPrintf("WARNING: #462 unsent fragments (not supposed to happen!)\n");
	}
}

/*
=================
CL_Netchan_Process
=================
*/
qboolean CL_Netchan_Process( netchan_t *chan, msg_t *msg ) {
	int ret;

	ret = Netchan_Process( chan, msg );
	if ( !ret ) {
		return qfalse;
	}

#ifdef LEGACY_PROTOCOL
	if(chan->compat)
		CL_Netchan_Decode(msg);
#endif

	return qtrue;
}
