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

Doom 3 GPL Source Code
Copyright (C) 1999-2011 id Software LLC, a ZeniMax Media company.

This file is part of the Doom 3 GPL Source Code ("Doom 3 Source Code").

Doom 3 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.

Doom 3 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 Doom 3 Source Code.  If not, see <http://www.gnu.org/licenses/>.

In addition, the Doom 3 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 Doom 3 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.

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

#ifndef __SCRIPT_INTERPRETER_H__
#define __SCRIPT_INTERPRETER_H__

#include "script/Script_Program.h"
#include "Entity.h"
#include "Game_local.h"

class idThread;

#define MAX_STACK_DEPTH	64
#define LOCALSTACK_SIZE 	(6144 * 2)

typedef struct prstack_s {
	int					s;
	const function_t	*f;
	int					stackbase;
} prstack_t;

class idInterpreter {
private:
	prstack_t			callStack[ MAX_STACK_DEPTH ];
	int					callStackDepth;
	int					maxStackDepth;

	byte				localstack[ LOCALSTACK_SIZE ];
	int					localstackUsed;
	int					localstackBase;
	int					maxLocalstackUsed;

	const function_t	*currentFunction;
	int					instructionPointer;

	int					popParms;
	const idEventDef	*multiFrameEvent;
	idEntity			*eventEntity;

	idThread			*thread;

	void				PopParms( int numParms );
	void				PushString( const char *string );
	void				PushVector( const idVec3 &vector );
	void				Push( intptr_t value );
	const char			*FloatToString( float value );
	void				AppendString( idVarDef *def, const char *from );
	void				SetString( idVarDef *def, const char *from );
	const char			*GetString( idVarDef *def );
	varEval_t			GetVariable( idVarDef *def );
	idEntity			*GetEntity( int entnum ) const;
	idScriptObject		*GetScriptObject( int entnum ) const;
	void				NextInstruction( int position );

	void				LeaveFunction( idVarDef *returnDef );
	void				CallEvent( const function_t *func, int argsize );
	void				CallSysEvent( const function_t *func, int argsize );

public:
	bool				doneProcessing;
	bool				threadDying;
	bool				terminateOnExit;
	bool				debug;

						idInterpreter();

	// save games
	void				Save( idSaveGame *savefile ) const;				// archives object for save game file
	void				Restore( idRestoreGame *savefile );				// unarchives object from save game file

	void				SetThread( idThread *pThread );

	void				StackTrace( void ) const;

	int					CurrentLine( void ) const;
	const char			*CurrentFile( void ) const;

	void				Error( const char *fmt, ... ) const id_attribute((format(printf,2,3)));
	void				Warning( const char *fmt, ... ) const id_attribute((format(printf,2,3)));
	void				DisplayInfo( void ) const;

	bool				BeginMultiFrameEvent( idEntity *ent, const idEventDef *event );
	void				EndMultiFrameEvent( idEntity *ent, const idEventDef *event );
	bool				MultiFrameEventInProgress( void ) const;

	void				ThreadCall( idInterpreter *source, const function_t *func, int args );
	void				EnterFunction( const function_t *func, bool clearStack );
	void				EnterObjectFunction( idEntity *self, const function_t *func, bool clearStack );

	bool				Execute( void );
	void				Reset( void );

	bool				GetRegisterValue( const char *name, idStr &out, int scopeDepth );
	int					GetCallstackDepth( void ) const;
	const prstack_t		*GetCallstack( void ) const;
	const function_t	*GetCurrentFunction( void ) const;
	idThread			*GetThread( void ) const;

};

/*
====================
idInterpreter::PopParms
====================
*/
ID_INLINE void idInterpreter::PopParms( int numParms ) {
	// pop our parms off the stack
	if ( localstackUsed < numParms ) {
		Error( "locals stack underflow\n" );
	}

	localstackUsed -= numParms;
}

/*
====================
idInterpreter::Push
====================
*/
ID_INLINE void idInterpreter::Push( intptr_t value ) {
	if ( localstackUsed + sizeof( intptr_t ) > LOCALSTACK_SIZE ) {
		Error( "Push: locals stack overflow\n" );
	}
	// DG: fix for 64bit Big Endian machines
	//*( intptr_t * )&localstack[ localstackUsed ]	= value;
	int val = value;
	assert(value == val && "I really assumed that value would always fit into 32bit");
	// dhewm3 used to store these values on localstack[] as intptr_t, even though
	// they always seem to be int32. Unfortunately, all the code reading localstack[]
	// gets the pointer to &localstack[ localstackUsed ] and then interprets that
	// as int* or float* or whatever.
	// So with 64bit machines it's stored as the wrong size (intptr_t is int64, int is int32),
	// and on Big Endian the values are just 0 (or UINT_MAX if value < 0) - on Little Endian
	// the first 4 bytes are the ones with actual data so the bug was hidden).
	// To fix this, now a regular itn is stored at `&localstack[ localstackUsed ]`,
	// as expected by the code using localstack[].
	// TODO: once this has been tested more (and the assertion above has never triggered),
	//       change idInterpreter::Push() to take a regular int argument instead of intptr_t.
	int *stackVar = ( int * )&localstack[ localstackUsed ];
	*stackVar = val;

	// even though a 32bit int is put onto the stack, increase it by sizeof(intptr_t)
	// so it remains aligned to multiples of the native pointer size
	localstackUsed += sizeof( intptr_t );
}

/*
====================
idInterpreter::PushVector
====================
*/
ID_INLINE void idInterpreter::PushVector( const idVec3 &vector ) {
	if ( localstackUsed + E_EVENT_SIZEOF_VEC > LOCALSTACK_SIZE ) {
		Error( "Push: locals stack overflow\n" );
	}
	*( idVec3 * )&localstack[ localstackUsed ] = vector;
	localstackUsed += E_EVENT_SIZEOF_VEC;
}

/*
====================
idInterpreter::PushString
====================
*/
ID_INLINE void idInterpreter::PushString( const char *string ) {
	if ( localstackUsed + MAX_STRING_LEN > LOCALSTACK_SIZE ) {
		Error( "PushString: locals stack overflow\n" );
	}
	idStr::Copynz( ( char * )&localstack[ localstackUsed ], string, MAX_STRING_LEN );
	localstackUsed += MAX_STRING_LEN;
}

/*
====================
idInterpreter::FloatToString
====================
*/
ID_INLINE const char *idInterpreter::FloatToString( float value ) {
	static char	text[ 32 ];

	if ( value == ( float )( int )value ) {
		sprintf( text, "%d", ( int )value );
	} else {
		sprintf( text, "%f", value );
	}
	return text;
}

/*
====================
idInterpreter::AppendString
====================
*/
ID_INLINE void idInterpreter::AppendString( idVarDef *def, const char *from ) {
	if ( def->initialized == idVarDef::stackVariable ) {
		idStr::Append( ( char * )&localstack[ localstackBase + def->value.stackOffset ], MAX_STRING_LEN, from );
	} else {
		idStr::Append( def->value.stringPtr, MAX_STRING_LEN, from );
	}
}

/*
====================
idInterpreter::SetString
====================
*/
ID_INLINE void idInterpreter::SetString( idVarDef *def, const char *from ) {
	if ( def->initialized == idVarDef::stackVariable ) {
		idStr::Copynz( ( char * )&localstack[ localstackBase + def->value.stackOffset ], from, MAX_STRING_LEN );
	} else {
		idStr::Copynz( def->value.stringPtr, from, MAX_STRING_LEN );
	}
}

/*
====================
idInterpreter::GetString
====================
*/
ID_INLINE const char *idInterpreter::GetString( idVarDef *def ) {
	if ( def->initialized == idVarDef::stackVariable ) {
		return ( char * )&localstack[ localstackBase + def->value.stackOffset ];
	} else {
		return def->value.stringPtr;
	}
}

/*
====================
idInterpreter::GetVariable
====================
*/
ID_INLINE varEval_t idInterpreter::GetVariable( idVarDef *def ) {
	if ( def->initialized == idVarDef::stackVariable ) {
		varEval_t val;
		val.intPtr = ( int * )&localstack[ localstackBase + def->value.stackOffset ];
		return val;
	} else {
		return def->value;
	}
}

/*
================
idInterpreter::GetEntity
================
*/
ID_INLINE idEntity *idInterpreter::GetEntity( int entnum ) const{
	assert( entnum <= MAX_GENTITIES );
	if ( ( entnum > 0 ) && ( entnum <= MAX_GENTITIES ) ) {
		return gameLocal.entities[ entnum - 1 ];
	}
	return NULL;
}

/*
================
idInterpreter::GetScriptObject
================
*/
ID_INLINE idScriptObject *idInterpreter::GetScriptObject( int entnum ) const {
	idEntity *ent;

	assert( entnum <= MAX_GENTITIES );
	if ( ( entnum > 0 ) && ( entnum <= MAX_GENTITIES ) ) {
		ent = gameLocal.entities[ entnum - 1 ];
		if ( ent && ent->scriptObject.data ) {
			return &ent->scriptObject;
		}
	}
	return NULL;
}

/*
====================
idInterpreter::NextInstruction
====================
*/
ID_INLINE void idInterpreter::NextInstruction( int position ) {
	// Before we execute an instruction, we increment instructionPointer,
	// therefore we need to compensate for that here.
	instructionPointer = position - 1;
}

#endif /* !__SCRIPT_INTERPRETER_H__ */
