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;
}