DELIMITER $$
CREATE OR REPLACE DEFINER=`vn`@`localhost` FUNCTION `vn`.`getNextDueDate`(vDated DATE, vGapDays INT, vPayDay INT)
	RETURNS date
	NOT DETERMINISTIC
	NO SQL
BEGIN

    DECLARE vReturn DATE;
	DECLARE vDuaDate DATE;
	DECLARE vDuaDateDay INT;
	
	SELECT TIMESTAMPADD(DAY, vGapDays, vDated) INTO vDuaDate;

	IF vDuaDate = CONCAT(YEAR(vDuaDate), '-03-01') THEN
			SET vDuaDate = TIMESTAMPADD (DAY , -1, vDuaDate); 
	ELSEIF vDuaDate = CONCAT(YEAR(vDuaDate), '-02-29') THEN
			SET vDuaDate = TIMESTAMPADD (DAY , -2, vDuaDate); 
	END IF;

	IF MONTH(vDuaDate) = 2 AND vPayDay = 30  THEN 
		IF util.isLeapYear(YEAR(vDuaDate)) THEN
			SET vPayDay = 29;
		ELSE
			SET vPayDay = 28;
		END IF;
	END IF;

	SELECT DAY(vDuaDate) INTO vDuaDateDay;   
	RETURN TIMESTAMPADD(MONTH, (vDuaDateDay > vPayDay), DATE_FORMAT(vDuaDate, CONCAT('%y/%m/', vPayDay)));
END$$
DELIMITER ;