Shopify Script - X% discount if cart is over $Y

min_discount_order_amount = Money.new(cents:100) * 30 #number of dollars needed in cart to get the discount
total = Input.cart.subtotal_price_was
discount = if total > min_discount_order_amount
              0.2 #discount percentage in decimal form
            else
              0
            end
message = "My message"

Input.cart.line_items.each do |line_item|
  product = line_item.variant.product
  next if product.gift_card?
  line_item.change_line_price(line_item.line_price * (1-discount), message: message) unless discount == 0
end

Output.cart = Input.cart