/*
===========================================================================
Copyright (C) 1999-2005 Id Software, Inc.

This file is part of Quake III Arena source code.

Quake III Arena 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 2 of the License,
or (at your option) any later version.

Quake III Arena 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 Quake III Arena source code; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
===========================================================================
*/
// cl_parse.c  -- parse a message received from the server

#include "client.h"

static const char* svc_strings[256] = {
	"svc_bad",

	"svc_nop",
	"svc_gamestate",
	"svc_configstring",
	"svc_baseline",	
	"svc_serverCommand",
	"svc_download",
	"svc_snapshot"
};

static void SHOWNET( const msg_t* msg, const char* s )
{
	if ( cl_shownet->integer >= 2 ) {
		Com_Printf( "%3i:%s\n", msg->readcount-1, s );
	}
}


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

MESSAGE PARSING

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


// parses deltas from the given base and adds the resulting entity to the current frame

static void CL_DeltaEntity( msg_t* msg, clSnapshot_t *frame, int newnum, entityState_t *old, qbool unchanged )
{
	entityState_t	*state;

	// save the parsed entity state into the big circular buffer so
	// it can be used as the source for a later delta
	state = &cl.parseEntities[cl.parseEntitiesNum & (MAX_PARSE_ENTITIES-1)];

	if ( unchanged ) {
		*state = *old;
	} else {
		MSG_ReadDeltaEntity( msg, old, state, newnum );
	}

	if ( state->number == (MAX_GENTITIES-1) ) {
		return;		// entity was delta removed
	}

	cl.parseEntitiesNum++;
	frame->numEntities++;
}


static void CL_ParsePacketEntities( msg_t *msg, clSnapshot_t *oldframe, clSnapshot_t *newframe)
{
	int			newnum;
	entityState_t	*oldstate;
	int			oldindex, oldnum;

	newframe->parseEntitiesNum = cl.parseEntitiesNum;
	newframe->numEntities = 0;

	// delta from the entities present in oldframe
	oldindex = 0;
	oldstate = NULL;
	if (!oldframe) {
		oldnum = 99999;
	} else {
		if ( oldindex >= oldframe->numEntities ) {
			oldnum = 99999;
		} else {
			oldstate = &cl.parseEntities[
				(oldframe->parseEntitiesNum + oldindex) & (MAX_PARSE_ENTITIES-1)];
			oldnum = oldstate->number;
		}
	}

	while ( 1 ) {
		// read the entity index number
		newnum = MSG_ReadBits( msg, GENTITYNUM_BITS );

		if ( newnum == (MAX_GENTITIES-1) ) {
			break;
		}

		if ( msg->readcount > msg->cursize ) {
			Com_Error (ERR_DROP,"CL_ParsePacketEntities: end of message");
		}

		while ( oldnum < newnum ) {
			// one or more entities from the old packet are unchanged
			if ( cl_shownet->integer == 3 ) {
				Com_Printf ("%3i:  unchanged: %i\n", msg->readcount, oldnum);
			}
			CL_DeltaEntity( msg, newframe, oldnum, oldstate, qtrue );

			oldindex++;

			if ( oldindex >= oldframe->numEntities ) {
				oldnum = 99999;
			} else {
				oldstate = &cl.parseEntities[
					(oldframe->parseEntitiesNum + oldindex) & (MAX_PARSE_ENTITIES-1)];
				oldnum = oldstate->number;
			}
		}
		if (oldnum == newnum) {
			// delta from previous state
			if ( cl_shownet->integer == 3 ) {
				Com_Printf ("%3i:  delta: %i\n", msg->readcount, newnum);
			}
			CL_DeltaEntity( msg, newframe, newnum, oldstate, qfalse );

			oldindex++;

			if ( oldindex >= oldframe->numEntities ) {
				oldnum = 99999;
			} else {
				oldstate = &cl.parseEntities[
					(oldframe->parseEntitiesNum + oldindex) & (MAX_PARSE_ENTITIES-1)];
				oldnum = oldstate->number;
			}
			continue;
		}

		if ( oldnum > newnum ) {
			// delta from baseline
			if ( cl_shownet->integer == 3 ) {
				Com_Printf ("%3i:  baseline: %i\n", msg->readcount, newnum);
			}
			CL_DeltaEntity( msg, newframe, newnum, &cl.entityBaselines[newnum], qfalse );
			continue;
		}

	}

	// any remaining entities in the old frame are copied over
	while ( oldnum != 99999 ) {
		// one or more entities from the old packet are unchanged
		if ( cl_shownet->integer == 3 ) {
			Com_Printf ("%3i:  unchanged: %i\n", msg->readcount, oldnum);
		}
		CL_DeltaEntity( msg, newframe, oldnum, oldstate, qtrue );

		oldindex++;

		if ( oldindex >= oldframe->numEntities ) {
			oldnum = 99999;
		} else {
			oldstate = &cl.parseEntities[
				(oldframe->parseEntitiesNum + oldindex) & (MAX_PARSE_ENTITIES-1)];
			oldnum = oldstate->number;
		}
	}
}


/*
If the snapshot is parsed properly, it will be copied to
cl.snap and saved in cl.snapshots[].  If the snapshot is invalid
for any reason, no changes to the state will be made at all.
*/
static void CL_ParseSnapshot( msg_t *msg )
{
	int			len;
	clSnapshot_t	*old;
	clSnapshot_t	newSnap;
	int			deltaNum;
	int			oldMessageNum;
	int			i, packetNum;

	// get the reliable sequence acknowledge number
	// NOTE: now sent with all server to client messages
	//clc.reliableAcknowledge = MSG_ReadLong( msg );

	// read in the new snapshot to a temporary buffer
	// we will only copy to cl.snap if it is valid
	Com_Memset (&newSnap, 0, sizeof(newSnap));

	// we will have read any new server commands in this
	// message before we got to svc_snapshot
	newSnap.serverCommandNum = clc.serverCommandSequence;

	newSnap.serverTime = MSG_ReadLong( msg );

	// now that we have a server time update,
	// we can consider the client pause (if active) truly over
	// see CL_Paused for the details
	cl_paused->modified = qfalse;

	newSnap.messageNum = clc.serverMessageSequence;

	deltaNum = MSG_ReadByte( msg );
	if ( !deltaNum ) {
		newSnap.deltaNum = -1;
	} else {
		newSnap.deltaNum = newSnap.messageNum - deltaNum;
	}
	newSnap.snapFlags = MSG_ReadByte( msg );

	// If the frame is delta compressed from data that we
	// no longer have available, we must suck up the rest of
	// the frame, but not use it, then ask for a non-compressed
	// message 
	if ( newSnap.deltaNum <= 0 ) {
		newSnap.valid = qtrue;		// uncompressed frame
		old = NULL;
		clc.demowaiting = qfalse;	// we can start recording now
	} else {
		old = &cl.snapshots[newSnap.deltaNum & PACKET_MASK];
		if ( !old->valid ) {
			// should never happen
			Com_Printf ("Delta from invalid frame (not supposed to happen!).\n");
		} else if ( old->messageNum != newSnap.deltaNum ) {
			// The frame that the server did the delta from
			// is too old, so we can't reconstruct it properly.
			Com_Printf ("Delta frame too old.\n");
		} else if ( cl.parseEntitiesNum - old->parseEntitiesNum > MAX_PARSE_ENTITIES-128 ) {
			Com_Printf ("Delta parseEntitiesNum too old.\n");
		} else {
			newSnap.valid = qtrue;	// valid delta parse
		}
	}

	// read areamask
	len = MSG_ReadByte( msg );

	if(len > sizeof(newSnap.areamask))
	{
		Com_Error (ERR_DROP,"CL_ParseSnapshot: Invalid size %d for areamask.", len);
		return;
	}

	MSG_ReadData( msg, &newSnap.areamask, len);

	// read playerinfo
	SHOWNET( msg, "playerstate" );
	if ( old ) {
		MSG_ReadDeltaPlayerstate( msg, &old->ps, &newSnap.ps );
	} else {
		MSG_ReadDeltaPlayerstate( msg, NULL, &newSnap.ps );
	}

	// read packet entities
	SHOWNET( msg, "packet entities" );
	CL_ParsePacketEntities( msg, old, &newSnap );

	// if not valid, dump the entire thing now that it has
	// been properly read
	if ( !newSnap.valid ) {
		return;
	}

	// clear the valid flags of any snapshots between the last
	// received and this one, so if there was a dropped packet
	// it won't look like something valid to delta from next
	// time we wrap around in the buffer
	oldMessageNum = cl.snap.messageNum + 1;

	if ( newSnap.messageNum - oldMessageNum >= PACKET_BACKUP ) {
		oldMessageNum = newSnap.messageNum - ( PACKET_BACKUP - 1 );
	}
	for ( ; oldMessageNum < newSnap.messageNum ; oldMessageNum++ ) {
		cl.snapshots[oldMessageNum & PACKET_MASK].valid = qfalse;
	}

	// copy to the current good spot
	cl.snap = newSnap;
	cl.snap.ping = 999;
	// calculate ping time
	for ( i = 0 ; i < PACKET_BACKUP ; i++ ) {
		packetNum = ( clc.netchan.outgoingSequence - 1 - i ) & PACKET_MASK;
		if ( cl.snap.ps.commandTime >= cl.outPackets[ packetNum ].p_serverTime ) {
			cl.snap.ping = cls.realtime - cl.outPackets[ packetNum ].p_realtime;
			break;
		}
	}
	// save the frame off in the backup array for later delta comparisons
	cl.snapshots[cl.snap.messageNum & PACKET_MASK] = cl.snap;

	if (cl_shownet->integer == 3) {
		Com_Printf( "   snapshot:%i  delta:%i  ping:%i\n", cl.snap.messageNum,
		cl.snap.deltaNum, cl.snap.ping );
	}

	cl.newSnapshots = qtrue;
}


//=====================================================================

int cl_connectedToPureServer;

// the systeminfo configstring has been changed, so parse the new info out of it
// this will happen at every gamestate, and possibly during gameplay

void CL_SystemInfoChanged()
{
	// these are cvars the client doesn't need nor want to set locally
	// no need to reject "sv_cheats" since it gets cleared by /map and set by /devmap
	static const char* rejectedCVars[] = {
		"sv_pure",
		"sv_paks",
		"sv_pakNames",
		"sv_referencedPaks",
		"sv_referencedPakNames",
		"sv_currentPak",
		"sv_serverid"
	};

	const char *s, *t;

	// don't set any vars when playing a demo
	if ( clc.demoplaying ) {
		return;
	}

	const char* systemInfo = cl.gameState.stringData + cl.gameState.stringOffsets[ CS_SYSTEMINFO ];

	// when the serverId changes, any further messages we send to the server will use this new serverId
	// https://zerowing.idsoftware.com/bugzilla/show_bug.cgi?id=475
	// in some cases, outdated cp commands might get sent with this new serverId
	cl.serverId = atoi( Info_ValueForKey( systemInfo, "sv_serverid" ) );

	s = Info_ValueForKey( systemInfo, "sv_cheats" );
	if ( atoi(s) == 0 ) {
		Cvar_SetCheatState();
	}

	// check pure server string
	// note: the CNQ3 client doesn't even read sv_pakNames anymore since it's of no use
	s = Info_ValueForKey( systemInfo, "sv_paks" );
	FS_PureServerSetLoadedPaks( s );

	s = Info_ValueForKey( systemInfo, "sv_referencedPaks" );
	t = Info_ValueForKey( systemInfo, "sv_referencedPakNames" );
	FS_PureServerSetReferencedPaks( s, t );

	qbool gameSet = qfalse;
	// scan through all the variables in the systeminfo and locally set cvars to match
	s = systemInfo;
	while ( s ) {
		char key[BIG_INFO_KEY], value[BIG_INFO_VALUE];
		Info_NextPair( &s, key, value );
		if ( !key[0] ) {
			break;
		}

		// reject unwanted cvars
		qbool rejected = qfalse;
		for ( int i = 0; i < ARRAY_LEN(rejectedCVars); ++i ) {
			if ( !Q_stricmp(key, rejectedCVars[i]) ) {
				rejected = qtrue;
				break;
			}
		}
		if ( rejected )
			continue;

		// ehw!
		if (!Q_stricmp(key, "fs_game"))
		{
			if (FS_CheckDirTraversal(value))
			{
				Com_Printf("WARNING: Server sent invalid fs_game value %s\n", value);
				continue;
			}
			gameSet = qtrue;
		}

		// servers are only allowed to modify specific sets of cvars
		int flags = Cvar_Flags(key);
		if (flags == CVAR_NONEXISTENT) {
			Cvar_Get( key, value, CVAR_SERVER_CREATED | CVAR_ROM );
		}
		else if (flags & (CVAR_SYSTEMINFO | CVAR_SERVER_CREATED)) {
			Cvar_Set( key, value );
		}
	}

	// if game folder should not be set and it is set at the client side
	if ( !gameSet && *Cvar_VariableString("fs_game") ) {
		Cvar_Set( "fs_game", "" );
	}

	cl_connectedToPureServer = Cvar_VariableValue( "sv_pure" );
}


static void CL_ParseGamestate( msg_t *msg )
{
	int				i;
	entityState_t	*es;
	int				newnum;
	entityState_t	nullstate;
	int				cmd;
	char			*s;

	Con_Close();

	clc.connectPacketCount = 0;

	// wipe local client state
	CL_ClearState();

	// all previous config string commands need to be marked as invalid
	for ( i = 0; i < MAX_RELIABLE_COMMANDS; ++i ) {
		const char* const cmdStr = clc.serverCommands[i];

		if ( !strncmp(cmdStr, "cs "  , 3) ||
			 !strncmp(cmdStr, "bcs0 ", 5) ||
			 !strncmp(cmdStr, "bcs1 ", 5) ||
			 !strncmp(cmdStr, "bcs2 ", 5) )
			 clc.serverCommandsBad[i] = qtrue;
	}

	// a gamestate always marks a server command sequence
	clc.serverCommandSequence = MSG_ReadLong( msg );

	// parse all the configstrings and baselines
	cl.gameState.dataCount = 1;	// leave a 0 at the beginning for uninitialized configstrings
	while ( 1 ) {
		cmd = MSG_ReadByte( msg );

		if ( cmd == svc_EOF ) {
			break;
		}

		if ( cmd == svc_configstring ) {
			int		len;

			i = MSG_ReadShort( msg );
			if ( i < 0 || i >= MAX_CONFIGSTRINGS ) {
				Com_Error( ERR_DROP, "configstring > MAX_CONFIGSTRINGS" );
			}
			s = MSG_ReadBigString( msg );
			len = strlen( s );

			if ( len + 1 + cl.gameState.dataCount > MAX_GAMESTATE_CHARS ) {
				Com_Error( ERR_DROP, "MAX_GAMESTATE_CHARS exceeded" );
			}

			// append it to the gameState string buffer
			cl.gameState.stringOffsets[ i ] = cl.gameState.dataCount;
			Com_Memcpy( cl.gameState.stringData + cl.gameState.dataCount, s, len + 1 );
			cl.gameState.dataCount += len + 1;
		} else if ( cmd == svc_baseline ) {
			newnum = MSG_ReadBits( msg, GENTITYNUM_BITS );
			if ( newnum < 0 || newnum >= MAX_GENTITIES ) {
				Com_Error( ERR_DROP, "Baseline number out of range: %i", newnum );
			}
			Com_Memset (&nullstate, 0, sizeof(nullstate));
			es = &cl.entityBaselines[ newnum ];
			MSG_ReadDeltaEntity( msg, &nullstate, es, newnum );
		} else {
			Com_Error( ERR_DROP, "CL_ParseGamestate: bad command byte" );
		}
	}

	clc.clientNum = MSG_ReadLong(msg);
	// read the checksum feed
	clc.checksumFeed = MSG_ReadLong( msg );

	// parse serverId and other cvars
	CL_SystemInfoChanged();

	// reinitialize the filesystem if the game directory has changed
	FS_ConditionalRestart( clc.checksumFeed );

	// This used to call CL_StartHunkUsers, but now we enter the download state before loading the cgame
	CL_InitDownloads();

	// make sure the game starts
	Cvar_Set( "cl_paused", "0" );
}


//=====================================================================


// a download message has been received from the server

static void CL_ParseDownload( msg_t *msg )
{
	if (!*clc.downloadTempName) {
		Com_Printf("Server sending download, but no download was requested\n");
		CL_AddReliableCommand( "stopdl" );
		return;
	}

	// read the data
	int block = MSG_ReadShort( msg );

	if ( !block )
	{
		// block zero is special, contains file size
		clc.downloadSize = MSG_ReadLong( msg );
		Cvar_SetValue( "cl_downloadSize", clc.downloadSize );

		if (clc.downloadSize < 0)
		{
			Com_Error( ERR_DROP, MSG_ReadString( msg ) );
			return;
		}
	}

	int size = MSG_ReadShort( msg );
	unsigned char data[MAX_MSGLEN];
	if (size < 0 || size > sizeof(data))
	{
		Com_Error( ERR_DROP, "CL_ParseDownload: Invalid size %d for download chunk.", size );
		return;
	}

	MSG_ReadData( msg, data, size );

	if (clc.downloadBlock != block) {
		Com_DPrintf( "CL_ParseDownload: Expected block %d, got %d\n", clc.downloadBlock, block );
		return;
	}

	// open the file if not opened yet
	if (!clc.download)
	{
		clc.download = FS_SV_FOpenFileWrite( clc.downloadTempName );
		if (!clc.download) {
			Com_Printf( "Could not create %s\n", clc.downloadTempName );
			CL_AddReliableCommand( "stopdl" );
			CL_NextDownload();
			return;
		}
	}

	if (size)
		FS_Write( data, size, clc.download );

	CL_AddReliableCommand( va("nextdl %d", clc.downloadBlock) );
	clc.downloadBlock++;

	clc.downloadCount += size;

	// So UI gets access to it
	Cvar_SetValue( "cl_downloadCount", clc.downloadCount );

	if (!size) { // A zero length block means EOF
		if (clc.download) {
			FS_FCloseFile( clc.download );
			clc.download = 0;

			// rename the file
			FS_SV_Rename( clc.downloadTempName, clc.downloadName );
		}
		*clc.downloadTempName = *clc.downloadName = 0;
		Cvar_Set( "cl_downloadName", "" );

		// send intentions now
		// We need this because without it, we would hold the last nextdl and then start
		// loading right away.  If we take a while to load, the server is happily trying
		// to send us that last block over and over.
		// Write it twice to help make sure we acknowledge the download
		CL_WritePacket();
		CL_WritePacket();

		// get another file if needed
		CL_NextDownload();
	}
}


/*
Command strings are just saved off until cgame asks for them
when it transitions a snapshot
*/
static void CL_ParseCommandString( msg_t* msg )
{
	const int seq = MSG_ReadLong( msg );
	const char* const s = MSG_ReadString( msg );

	// see if we have already stored it off
	if ( clc.serverCommandSequence >= seq ) {
		return;
	}
	clc.serverCommandSequence = seq;

	const int index = seq & (MAX_RELIABLE_COMMANDS - 1);
	Q_strncpyz( clc.serverCommands[ index ], s, sizeof( clc.serverCommands[ index ] ) );
	clc.serverCommandsBad[ index ] = qfalse;

	// We normally don't process commands before being CA_ACTIVE,
	// but it's possible we receive a "disconnect" command while
	// still being CA_PRIMED.
	// Therefore, we have to make an exception for "disconnect" right here
	// to avoid waiting for a snapshot forever.
	if ( cls.state == CA_PRIMED ) {
		Cmd_TokenizeString(s);
		if ( !Q_stricmp( Cmd_Argv(0), "disconnect" ) ) {
			if ( Cmd_Argc() >= 2 )
				Com_Error( ERR_DROP, "Server disconnected: %s", Cmd_Argv(1) );
			else
				Com_Error( ERR_DROP, "Server disconnected" );
		}
	}
}


void CL_ParseServerMessage( msg_t *msg )
{
	int			cmd;

	if ( cl_shownet->integer == 1 ) {
		Com_Printf ("%i ",msg->cursize);
	} else if ( cl_shownet->integer >= 2 ) {
		Com_Printf ("------------------\n");
	}

	MSG_Bitstream( msg );

	// get the reliable sequence acknowledge number
	clc.reliableAcknowledge = MSG_ReadLong( msg );

	if ( clc.reliableAcknowledge < clc.reliableSequence - MAX_RELIABLE_COMMANDS ) {
		clc.reliableAcknowledge = clc.reliableSequence;
	}

	//
	// parse the message
	//
	while ( 1 ) {
		if ( msg->readcount > msg->cursize ) {
			Com_Error (ERR_DROP,"CL_ParseServerMessage: read past end of server message");
			break;
		}

		cmd = MSG_ReadByte( msg );

		if ( cmd == svc_EOF) {
			SHOWNET( msg, "END OF MESSAGE" );
			break;
		}

		if ( cl_shownet->integer >= 2 ) {
			if ( !svc_strings[cmd] ) {
				Com_Printf( "%3i:BAD CMD %i\n", msg->readcount-1, cmd );
			} else {
				SHOWNET( msg, svc_strings[cmd] );
			}
		}

		switch ( cmd ) {
		default:
			Com_Error( ERR_DROP, "CL_ParseServerMessage: Illegible server message\n" );
			break;
		case svc_nop:
			break;
		case svc_serverCommand:
			CL_ParseCommandString( msg );
			break;
		case svc_gamestate:
			CL_ParseGamestate( msg );
			break;
		case svc_snapshot:
			CL_ParseSnapshot( msg );
			break;
		case svc_download:
			CL_ParseDownload( msg );
			break;
		}
	}
}