-- Shop Product Variation Link

CREATE OR REPLACE FUNCTION before_insert_Shop_User_Basket()
RETURNS TRIGGER AS $$
BEGIN
	IF NEW.created_on IS NULL THEN
		NEW.created_on = CURRENT_TIMESTAMP;
	END IF;
    IF NEW.created_by IS NULL THEN
		NEW.created_by = CURRENT_USER;
	END IF;

	RETURN NEW;
END;
$$ LANGUAGE plpgsql;

CREATE OR REPLACE TRIGGER tri_before_insert_Shop_User_Basket
BEFORE INSERT ON Shop_User_Basket
FOR EACH ROW
EXECUTE FUNCTION before_insert_Shop_User_Basket();


CREATE OR REPLACE FUNCTION before_update_Shop_User_Basket()
RETURNS TRIGGER AS $$
BEGIN
	IF NEW.id_change_set_user <=> OLD.id_change_set_user THEN
		RAISE EXCEPTION 'New change Set ID must be provided.'
			USING ERRCODE = '45000';
    END IF;
    
    INSERT INTO Shop_User_Basket_Audit (
		id_item,
        name_field,
        value_prev,
        value_new,
        id_change_set_user
    )
    -- Changed id_user
	SELECT NEW.id_item, 'id_user', OLD.id_user, NEW.id_user, NEW.id_change_set_user
		WHERE NOT OLD.id_user <=> NEW.id_user
	UNION
	-- Changed id_product
	SELECT NEW.id_item, 'id_product', OLD.id_product, NEW.id_product, NEW.id_change_set_user
		WHERE NOT OLD.id_product <=> NEW.id_product
	UNION
	-- Changed quantity
	SELECT NEW.id_item, 'quantity', CONVERT(OLD.quantity, CHAR), CONVERT(NEW.quantity, CHAR), NEW.id_change_set_user
		WHERE NOT (OLD.quantity <=> NEW.quantity)
	UNION
    -- Changed active
	SELECT NEW.id_item, 'active', CONVERT(CONVERT(OLD.active, SIGNED), CHAR), CONVERT(CONVERT(NEW.active, SIGNED), CHAR), NEW.id_change_set_user
		WHERE NOT (OLD.active <=> NEW.active)
	;

	RETURN NEW;
END;
$$ LANGUAGE plpgsql;

CREATE OR REPLACE TRIGGER tri_before_update_Shop_User_Basket
BEFORE UPDATE ON Shop_User_Basket
FOR EACH ROW
EXECUTE FUNCTION before_update_Shop_User_Basket();