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

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

This file is part of the Return to Castle Wolfenstein multiplayer GPL Source Code (“RTCW MP Source Code”).  

RTCW MP 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 MP 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 MP Source Code.  If not, see <http://www.gnu.org/licenses/>.

In addition, the RTCW MP 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 MP 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 "server.h"

#ifdef LEGACY_PROTOCOL
/*
==============
SV_Netchan_Encode

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

==============
*/
static void SV_Netchan_Encode(client_t *client, msg_t *msg, const char *clientCommandString)
{
	long i, index;
	byte key, *string;
	int	srdc, sbit;
	qboolean soob;

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

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

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

	/* reliableAcknowledge = */ MSG_ReadLong(msg);

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

	string = (byte *) clientCommandString;
	index = 0;
	// xor the client challenge with the netchan sequence number
	key = client->challenge ^ client->netchan.outgoingSequence;
	for ( i = SV_ENCODE_START; i < msg->cursize; i++ ) {
		// modify the key with the last received 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++;
		// encode the data with this key
		*( msg->data + i ) = *( msg->data + i ) ^ key;
	}
}

/*
==============
SV_Netchan_Decode

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

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

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

	msg->oob = qfalse;

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

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

	string = (byte *)client->reliableCommands[ reliableAcknowledge & ( MAX_RELIABLE_COMMANDS - 1 ) ];
	index = 0;
	//
	key = client->challenge ^ serverId ^ messageAcknowledge;
	for ( i = msg->readcount + SV_DECODE_START; i < msg->cursize; i++ ) {
		// modify the key with the last sent and acknowledged server 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

/*
=================
SV_Netchan_FreeQueue
=================
*/
void SV_Netchan_FreeQueue(client_t *client)
{
	netchan_buffer_t *netbuf, *next;
	
	for(netbuf = client->netchan_start_queue; netbuf; netbuf = next)
	{
		next = netbuf->next;
		Z_Free(netbuf);
	}
	
	client->netchan_start_queue = NULL;
	client->netchan_end_queue = &client->netchan_start_queue;
}

/*
=================
SV_Netchan_TransmitNextInQueue
=================
*/
void SV_Netchan_TransmitNextInQueue(client_t *client)
{
	netchan_buffer_t *netbuf;
		
	Com_DPrintf("#462 Netchan_TransmitNextFragment: popping a queued message for transmit\n");
	netbuf = client->netchan_start_queue;

#ifdef LEGACY_PROTOCOL
	if(client->compat)
		SV_Netchan_Encode(client, &netbuf->msg, netbuf->clientCommandString);
#endif

	Netchan_Transmit(&client->netchan, netbuf->msg.cursize, netbuf->msg.data);

	// pop from queue
	client->netchan_start_queue = netbuf->next;
	if(!client->netchan_start_queue)
	{
		Com_DPrintf("#462 Netchan_TransmitNextFragment: emptied queue\n");
		client->netchan_end_queue = &client->netchan_start_queue;
	}
	else
		Com_DPrintf("#462 Netchan_TransmitNextFragment: remaining queued message\n");

	Z_Free(netbuf);
}

/*
=================
SV_Netchan_TransmitNextFragment
Transmit the next fragment and the next queued packet
Return number of ms until next message can be sent based on throughput given by client rate,
-1 if no packet was sent.
=================
*/

int SV_Netchan_TransmitNextFragment(client_t *client)
{
	if(client->netchan.unsentFragments)
	{
		Netchan_TransmitNextFragment(&client->netchan);
		return SV_RateMsec(client);
	}
	else if(client->netchan_start_queue)
	{
		SV_Netchan_TransmitNextInQueue(client);
		return SV_RateMsec(client);
	}
	
	return -1;
}

/*
===============
SV_Netchan_Transmit

TTimo
show_bug.cgi?id=462
if there are some unsent fragments (which may happen if the snapshots
and the gamestate are fragmenting, and collide on send for instance)
then buffer them and make sure they get sent in correct order
================
*/
void SV_Netchan_Transmit( client_t *client, msg_t *msg)
{
	MSG_WriteByte( msg, svc_EOF );

	if(client->netchan.unsentFragments || client->netchan_start_queue)
	{
		netchan_buffer_t *netbuf;
		//Com_DPrintf("SV_Netchan_Transmit: there are unsent fragments remaining\n");
		netbuf = (netchan_buffer_t *) Z_Malloc(sizeof(netchan_buffer_t));
		// store the msg, we can't store it encoded, as the encoding depends on stuff we still have to finish sending
		MSG_Copy( &netbuf->msg, netbuf->msgBuffer, sizeof( netbuf->msgBuffer ), msg );
#ifdef LEGACY_PROTOCOL
		if(client->compat)
		{
			Q_strncpyz(netbuf->clientCommandString, client->lastClientCommandString,
				   sizeof(netbuf->clientCommandString));
		}
#endif
		netbuf->next = NULL;
		// insert it in the queue, the message will be encoded and sent later
		*client->netchan_end_queue = netbuf;
		client->netchan_end_queue = &( *client->netchan_end_queue )->next;
	}
	else
	{
#ifdef LEGACY_PROTOCOL
		if(client->compat)
			SV_Netchan_Encode(client, msg, client->lastClientCommandString);
#endif
		Netchan_Transmit( &client->netchan, msg->cursize, msg->data );
	}
}

/*
=================
Netchan_SV_Process
=================
*/
qboolean SV_Netchan_Process( client_t *client, msg_t *msg ) {
	int ret;
	ret = Netchan_Process( &client->netchan, msg );
	if ( !ret ) {
		return qfalse;
	}

#ifdef LEGACY_PROTOCOL
	if(client->compat)
		SV_Netchan_Decode(client, msg);
#endif

	return qtrue;
}