Shopify Script to discount items in cart based on customer tag, absence of discount code, and excluded products

line-item-script.rb

products_to_exclude = [444750805, 444750821] #product ids to exclude
trigger_customer_tag = 'member-50' #customer tags to trigger script discount


if Input.cart&.customer&.tags.include?(trigger_customer_tag) && Input.cart&.discount_code == nil #does the customer have the right tag, and are there no discounts applied?
  Input.cart.line_items.each do |line_item|
    product = line_item.variant.product
    next if product.gift_card? # don't discount gift cards
    next if products_to_exclude.include?(product.id) # don't discount excluded products
    line_item.change_line_price(line_item.line_price * 0.50, message: "Pro Deal - 50% Discount") #discount everything else by X%
  end
end

Output.cart = Input.cart