-- Shop Image

CREATE OR REPLACE FUNCTION before_insert_Shop_Image()
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_Image
BEFORE INSERT ON Shop_Image
FOR EACH ROW
EXECUTE FUNCTION before_insert_Shop_Image();


CREATE OR REPLACE FUNCTION before_update_Shop_Image()
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;
    IF ISNULL(NEW.id_product) AND ISNULL(NEW.id_permutation) THEN
		RAISE EXCEPTION 'Image must NOT have ID for product AND product permutation.'
			USING ERRCODE = '45000';
    END IF;
    
    INSERT INTO Shop_Image_Audit (
		id_image,
        name_field,
        value_prev,
        value_new,
        id_change_set
    )
    -- Changed id_type_image
	SELECT NEW.id_image, 'id_type_image', CONVERT(OLD.id_type_image, CHAR), CONVERT(NEW.id_type_image, CHAR), NEW.id_change_set
		WHERE NOT OLD.id_type_image <=> NEW.id_type_image
    UNION
    -- Changed id_type_file
	SELECT NEW.id_image, 'id_type_file', CONVERT(OLD.id_type_file, CHAR), CONVERT(NEW.id_type_file, CHAR), NEW.id_change_set
		WHERE NOT OLD.id_type_file <=> NEW.id_type_file
    UNION
    -- Changed id_product
	SELECT NEW.id_image, 'id_product', CONVERT(OLD.id_product, CHAR), CONVERT(NEW.id_product, CHAR), NEW.id_change_set
		WHERE NOT OLD.id_product <=> NEW.id_product
    UNION
    -- Changed id_permutation
	SELECT NEW.id_image, 'id_permutation', CONVERT(OLD.id_permutation, CHAR), CONVERT(NEW.id_permutation, CHAR), NEW.id_change_set
		WHERE NOT OLD.id_permutation <=> NEW.id_permutation
    UNION
    -- Changed url
	SELECT NEW.id_image, 'url', OLD.url, NEW.url, NEW.id_change_set
		WHERE NOT OLD.url <=> NEW.url
	UNION
	-- Changed active
	SELECT NEW.id_image, 'active', CONVERT(CONVERT(OLD.active, SIGNED), CHAR), CONVERT(CONVERT(NEW.active, SIGNED), CHAR), NEW.id_change_set
		WHERE NOT (OLD.active <=> NEW.active)
	UNION
	-- Changed display_order
	SELECT NEW.id_image, 'display_order', CONVERT(OLD.display_order, CHAR), CONVERT(NEW.display_order, CHAR), NEW.id_change_set
		WHERE NOT (OLD.display_order <=> NEW.display_order)
	;

	RETURN NEW;
END;
$$ LANGUAGE plpgsql;

CREATE OR REPLACE TRIGGER tri_before_update_Shop_Image
BEFORE UPDATE ON Shop_Image
FOR EACH ROW
EXECUTE FUNCTION before_update_Shop_Image();