var var_qty = [];

function check_variant_qty(varid) {
	curr_qty = parseFloat(document.getElementById("var_amount_"+varid).value);

	if (curr_qty < var_qty[varid][0]) {
		document.getElementById("var_amount_"+varid).value = var_qty[varid][0];
 	} else if (curr_qty > var_qty[varid][1]) {
		document.getElementById("var_amount_"+varid).value = var_qty[varid][1];
 	} else {
		document.getElementById("var_amount_"+varid).value = curr_qty - curr_qty%var_qty[varid][2];
	}

	if (curr_qty != document.getElementById("var_amount_"+varid).value)
		alert ('The product amount has been changed to '+document.getElementById("var_amount_"+varid).value+',\nbecause the minimal order amount is '+var_qty[varid][0]+',\nmaximum order amount is '+var_qty[varid][1]+',\n and ordered amount should be multiple of '+var_qty[varid][2]+'.'); 
	
}

function decrease_variant_qty(varid) {

	curr_qty = parseFloat(document.getElementById("var_amount_"+varid).value);
	new_qty = curr_qty-var_qty[varid][2];
	
	if (new_qty < var_qty[varid][0]) {
		new_qty = var_qty[varid][0];
	}		

    document.getElementById("var_amount_"+varid).value = new_qty;
}

function increase_variant_qty(varid) {

    curr_qty = parseFloat(document.getElementById("var_amount_"+varid).value);
    new_qty = curr_qty+var_qty[varid][2];
    
    if (new_qty > var_qty[varid][1]) {
        new_qty = var_qty[varid][1];
    }       

    document.getElementById("var_amount_"+varid).value = new_qty;
}