--
-- ec_shipment_cost/1
--
create or replace function ec_shipment_cost(
  integer
) returns numeric as $$

DECLARE
	v_shipment_id	alias for $1;
        v_price         numeric;
        v_shipping      numeric;
        v_certificate   numeric;
        v_tax           numeric;
BEGIN
        v_price := ec_shipment_price(v_shipment_id);
        v_shipping := ec_shipment_shipping(v_shipment_id);
        v_tax := ec_shipment_tax(v_shipment_id);
        v_certificate := ec_shipment_gift_certificate(v_shipment_id);

        return v_price + v_shipping - v_certificate + v_tax;
END;$$ language plpgsql;