InvoiceDiscountTable::getEmptyFields

static function getEmptyFields($discount)
{
	if (!is_array($discount))
		return false;
	if (empty($discount))
		return self::$requiredFields;

	$fields = array();
	foreach (self::$replaceFields as $dest => $src)
	{
		if (!isset($discount[$dest]) && isset($discount[$src]))
			$discount[$dest] = $discount[$src];
	}
	unset($dest, $src);
	foreach (self::$requiredFields as $fieldName)
	{
		if (!isset($discount[$fieldName]))
			$fields[] = (isset(self::$revertFields[$fieldName]) ? self::$revertFields[$fieldName] :$fieldName);
	}
	unset($fieldName);

	return $fields;
}