X for $X Shopify Script Editor

script.rb

X_FOR_X_DISCOUNT_ENABLED = false
X_FOR_X_RULES_ARR = [
  {
    TAG_NAME: 'tagname_something',
    PRODUCT_COUNT: 3,
    PRICE: 9900,
    MESSAGE: '2 for $30 collection'
  }
]

class XForXCampaign
  def initialize(selector, count, total_price, message)
    @selector = selector
    @count = count
    @total_price = total_price
    @message = message
  end
  
  def run(cart)
    foundWithTag = 0;
    discountsApplied = 0;
    howManyToApply = 0;
    
    Input.cart.line_items.each do |line_item|
      foundWithTag += line_item.quantity if @selector.match?(line_item)
    end
    
    # find modulo multiples
    howManyToApply = (foundWithTag / @count).floor * @count 

    if foundWithTag >= @count
      Input.cart.line_items.each do |line_item|
        break if discountsApplied == howManyToApply
        new_line_price = (@total_price / @count).floor
        line_item.change_line_price(Money.new(cents: new_line_price), message: @message)
        discountsApplied += 1
      end
    end
  end
end

CAMPAIGNS = []

if (X_FOR_X_DISCOUNT_ENABLED)
  X_FOR_X_RULES_ARR.each do |campaign|
    CAMPAIGNS += [
      XForXCampaign.new(
        TagSelector.new(campaign[:TAG_NAME]),
        campaign[:PRODUCT_COUNT],
        campaign[:PRICE],
        campaign[:MESSAGE]
      ),
    ]
  end
end

CAMPAIGNS.each do |campaign|
  campaign.run(Input.cart)
end