int checkweight_sub(struct map_session_data *sd, int nameid, int amount, int slots, int amount2)
{
	short amount2 = 0;

	switch( pc_checkadditem(sd, nameid, amount) ) {
		case CHKADDITEM_EXIST: // item is already in inventory, but there is still space for the requested amount
			break;
		case CHKADDITEM_NEW:
			if( itemdb_isstackable(nameid) ){// stackable
				amount2++;
				if( slots < amount2 )
					return -1;
			}
			else {// non-stackable
				amount2 += amount;
				if( slots < amount2 )
					return -1;
			}
			break;
		case CHKADDITEM_OVERAMOUNT:
			return -1;
	} //end switch

	return amount2;
}

/*==========================================
 * Check if item with this amount can fit in inventory
 * Checking : weight, stack amount >32k, slots amount >(MAX_INVENTORY)
 * Return
 *	0 : fail
 *	1 : success (npc side only)
 *------------------------------------------*/
BUILDIN_FUNC(checkweight)
{
	int nameid, amount, slots, amount2=0;
	unsigned int weight=0, i, nbargs;

	TBL_PC *sd = script_rid2sd(st);
	nullpo_retr(1,sd);

	if( ( sd = script_rid2sd(st) ) == NULL )
		return 0;

	if(!strcmp(script_getfuncname(st),"checkweight")) {
		struct item_data* id = NULL;
		struct script_data* data;

		nbargs = script_lastdata(st)+1;
		if(nbargs%2){
			ShowError("buildin_checkweight: Invalid nb of args should be a multiple of 2.\n");
			script_pushint(st,0);
			return 1;
		}

		slots = pc_inventoryblank(sd); //nb of empty slot

		for(i=2; i<nbargs; i=i+2){
			data = script_getdata(st,i);
			get_val(st, data);  // convert into value in case of a variable
			if( data_isstring(data) ) // item name
				id = itemdb_searchname(conv_str(st, data));
			else // item id
				id = itemdb_exists(conv_num(st, data));
			if( id == NULL ) {
				ShowError("buildin_checkweight: Invalid item '%s'.\n", script_getstr(st,i));  // returns string, regardless of what it was
				script_pushint(st,0);
				return 1;
			}
			nameid = id->nameid;
			amount = script_getnum(st,i+1);

			if(amount < 0 ){
				ShowError("buildin_checkweight: Invalid amount '%d'.\n", amount);
				amount2 = -1;
				break;
			}
			weight += itemdb_weight(nameid)*amount;
			if( weight + sd->weight > sd->max_weight ) {
				amount2 = -1;
				break;
			}
			if(amount2 = checkweight_sub(sd,nameid,amount,slots,amount2) == -1)
				break;
		}
	} else {
		//variable for array parsing
		struct script_data* data_it;
		struct script_data* data_nb;
		const char* name_it;
		const char* name_nb;
		int32 id_it, id_nb;
		int32 idx_it, idx_nb;
		int nb_it, nb_nb; //array size

		data_it = script_getdata(st, 2);
		data_nb = script_getdata(st, 3);

		if( !data_isreference(data_it) || !data_isreference(data_nb)) {
			ShowError("script:checkweight2: parameter not a variable\n");
			script_pushint(st,0);
			return 1;// not a variable
		}
		id_it = reference_getid(data_it);
		id_nb = reference_getid(data_nb);
		idx_it = reference_getindex(data_it);
		idx_nb = reference_getindex(data_nb);
		name_it = reference_getname(data_it);
		name_nb = reference_getname(data_nb);

		if( not_array_variable(*name_it) || not_array_variable(*name_nb)) {
			ShowError("script:checkweight2: illegal scope\n");
			script_pushint(st,0);
			return 1;// not supported
		}
		if(is_string_variable(name_it) || is_string_variable(name_nb)){
			ShowError("script:checkweight2: illegal type, need int\n");
			script_pushint(st,0);
			return 1;// not supported
		}
		nb_it = getarraysize(st, id_it, idx_it, 0, reference_getref(data_it));
		nb_nb = getarraysize(st, id_nb, idx_nb, 0, reference_getref(data_nb));
		if(nb_it != nb_nb) {
			ShowError("Size mistmatch: nb_it=%d, nb_nb=%d\n",nb_it,nb_nb);
			amount2 = -1;
		}

		slots = pc_inventoryblank(sd); //nb of empty slot

		for(i=0; i<nb_it; i++) {
			nameid = (int32)__64BPRTSIZE(get_val2(st,reference_uid(id_it,idx_it+i),reference_getref(data_it)));
			script_removetop(st, -1, 0);
			amount = (int32)__64BPRTSIZE(get_val2(st,reference_uid(id_nb,idx_nb+i),reference_getref(data_nb)));
			script_removetop(st, -1, 0);

			if(amount2 == -1) 
				continue; //cpntonie to depop rest
			if(itemdb_exists(nameid) == NULL ){
				ShowError("buildin_checkweight2: Invalid item '%d'.\n", nameid);
				amount2 = -1;
				continue;
			}
			if(amount < 0 ){
				ShowError("buildin_checkweight2: Invalid amount '%d'.\n", amount);
				amount2 = -1;
				continue;
			}
			weight += itemdb_weight(nameid)*amount;
			if( weight + sd->weight > sd->max_weight ) {
				amount2 = -1;
				continue;
			}
			amount2 = checkweight_sub(sd,nameid,amount,slots,amount2);
		} //end loop DO NOT break it prematurly we need to depop all stack
	}

	(amount2 == -1)?script_pushint(st,0):script_pushint(st,1);
	return 0;
}