Shopify script editor use product tag not id

I'm using this code to add a free gift when cart reaches X quantity (3 different thresholds and gifts). Script works perfectly fine, but I want to to ad a product with the product tags, not the product ID. I'm new to ruby, so any advice is apreciated.

This is the script (I'm just uploading 1 threshold, if i put the 3 of them it's to much code and won't let me upload it):

FREEGIFT_X = [
  {
    product_selector_match_type: :include,
    product_selector_type: :product_id,
    product_selectors: [6678361931933],
    threshold: 4500,
    quantity_to_discount: 1,
    discount_type: :percent,
    discount_amount: 100,
    discount_message: 'Spend 4500 and get a free XXX',
  }
]

class ProductSelector
  def initialize(match_type, selector_type, selectors)
    @match_type = match_type
    @comparator = match_type == :include ? 'any?' : 'none?'
    @selector_type = selector_type
    @selectors = selectors
  end

  def match?(line_item)
    if self.respond_to?(@selector_type)
      self.send(@selector_type, line_item)
    else
      raise RuntimeError.new('Invalid product selector type')
    end
  end

  def tag(line_item)
    product_tags = line_item.variant.product.tags.map { |tag| tag.downcase.strip }
    @selectors = @selectors.map { |selector| selector.downcase.strip }
    (@selectors & product_tags).send(@comparator)
  end

  def type(line_item)
    @selectors = @selectors.map { |selector| selector.downcase.strip }
    (@match_type == :include) == @selectors.include?(line_item.variant.product.product_type.downcase.strip)
  end

  def vendor(line_item)
    @selectors = @selectors.map { |selector| selector.downcase.strip }
    (@match_type == :include) == @selectors.include?(line_item.variant.product.vendor.downcase.strip)
  end

  def product_id(line_item)
    (@match_type == :include) == @selectors.include?(line_item.variant.product.id)
  end

  def variant_id(line_item)
    (@match_type == :include) == @selectors.include?(line_item.variant.id)
  end

  def subscription(line_item)
    !line_item.selling_plan_id.nil?
  end

  def all(line_item)
    true
  end
end

class DiscountApplicator
  def initialize(discount_type, discount_amount, discount_message)
    @discount_type = discount_type
    @discount_message = discount_message

    @discount_amount = if discount_type == :percent
      1 - (discount_amount * 0.01)
    else
      Money.new(cents: 100) * discount_amount
    end
  end

  def apply(line_item)
    new_line_price = if @discount_type == :percent
      line_item.line_price * @discount_amount
    else
      [line_item.line_price - (@discount_amount * line_item.quantity), Money.zero].max
    end

    line_item.change_line_price(new_line_price, message: @discount_message)
  end
end

# DiscountLoop

class DiscountLoop
  def initialize(discount_applicator)
    @discount_applicator = discount_applicator
  end

  def loop_items(cart, line_items, num_to_discount)
    line_items.each do |line_item|
      break if num_to_discount <= 0

      if line_item.quantity > num_to_discount
        split_line_item = line_item.split(take: num_to_discount)
        @discount_applicator.apply(split_line_item)
        position = cart.line_items.find_index(line_item)
        cart.line_items.insert(position + 1, split_line_item)
        break
      else
        @discount_applicator.apply(line_item)
        num_to_discount -= line_item.quantity
      end
    end
  end
end


# DiscCampaign
    
class DiscCampaign
  def initialize(campaigns)
    @campaigns = campaigns
  end

  def run(cart)
    @campaigns.each do |campaign|
      threshold = Money.new(cents: 100) * campaign[:threshold]

      next if cart.subtotal_price < threshold

      product_selector = ProductSelector.new(
        campaign[:product_selector_match_type],
        campaign[:product_selector_type],
        campaign[:product_selectors],
      )

      eligible_items = cart.line_items.select { |line_item| product_selector.match?(line_item) }

      next if eligible_items.nil?

      eligible_items = eligible_items.sort_by { |line_item| line_item.variant.price }
      num_to_discount = campaign[:quantity_to_discount]
      cart_total = cart.subtotal_price

      eligible_items.each do |line_item|
        break if num_to_discount <= 0

        if line_item.quantity > num_to_discount
          cart_total -= line_item.variant.price * num_to_discount
          break
        else
          cart_total -= line_item.line_price
          num_to_discount -= line_item.quantity
        end
      end

      next if cart_total < threshold

      discount_applicator = discount_applicator = DiscountApplicator.new(
        campaign[:discount_type],
        campaign[:discount_amount],
        campaign[:discount_message]
      )

      discount_loop = DiscountLoop.new(discount_applicator)
      discount_loop.loop_items(cart, eligible_items, campaign[:quantity_to_discount])
    end
  end
end

CAMPAIGNS = [
  DiscCampaign.new(FREEGIFT_X),
]

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

Output.cart = Input.cart