-- Shop General

CREATE OR REPLACE FUNCTION before_insert_Shop_General()
RETURNS TRIGGER AS $$
BEGIN
	NEW.created_on = CURRENT_TIMESTAMP;
    NEW.created_by = CURRENT_USER;

	RETURN NEW;
END;
$$ LANGUAGE plpgsql;

CREATE OR REPLACE TRIGGER tri_before_insert_Shop_General
BEFORE INSERT ON Shop_General
FOR EACH ROW
EXECUTE FUNCTION before_insert_Shop_General();


CREATE OR REPLACE FUNCTION before_update_Shop_General()
RETURNS TRIGGER AS $$
BEGIN
	IF OLD.id_change_set IS NOT DISTINCT FROM NEW.id_change_set THEN
		RAISE EXCEPTION 'New change Set ID must be provided.'
			USING ERRCODE = '45000';
    END IF;
    
    INSERT INTO Shop_General_Audit (
		id_general,
        name_field,
        value_prev,
        value_new,
        id_change_set
    )
    -- Changed quantity max
	SELECT NEW.id_general, 'quantity_max', CONVERT(OLD.quantity_max, CHAR), CONVERT(NEW.quantity_max, CHAR), NEW.id_change_set
		WHERE NOT OLD.quantity_max <=> NEW.quantity_max
	;

	RETURN NEW;
END;
$$ LANGUAGE plpgsql;

CREATE OR REPLACE TRIGGER tri_before_update_Shop_General
BEFORE UPDATE ON Shop_General
FOR EACH ROW
EXECUTE FUNCTION before_update_Shop_General();