discount.rb

# A class that knows how to calculate the discount for a line item, given a
# number of cents to discount each unit of item by.
class MoneyDiscount
  def initialize(cents)
    @amount = Money.new(cents: cents)
  end

  def calculate(line_item)
    @amount * line_item.quantity
  end
end

# A class that knows how to calculate the discount for a line item, given a
# number representing the percentage to discount each unit of item by.
class PercentageDiscount
  def initialize(percent)
    # Calculate the percentage, while ensuring that Decimal values are used in
    # order to maintain precision.
    @percent = Decimal.new(percent) / 100.0
  end

  def calculate(line_item)
    line_item.line_price * @percent
  end
end

# A class that knows how to apply a discount over a cart, for line items that
# match a certain product ID.
# A class that knows how to apply a discount over a cart, for line items that
# match a certain product ID.
class BundleDiscountCampaign
  # Initialize the instance with the discounted product ID, the Discount
  # instance that will be used to calculate the discount, and the message that
  # will be used to describe the discount.
  def initialize(product_type, discount, message)
    @product_type = product_type
    @discount = discount
    @message = message
    @bundle_count = 0
    @free_items_count = 0
  end

  # Apply the discount to a given Cart. Also prints debugging lines to the
  # console with the variant IDs of the line items being discounted and the
  # discount amounts being applied.
  def run(cart)

    case cart.discount_code
      when CartDiscount::Percentage
        @discount = PercentageDiscount.new(cart.discount_code.percentage)
      when CartDiscount::FixedAmount
        @discount = MoneyDiscount.new(cart.discount_code.amount.cents)
      else
    end

    
    cart.line_items.each do |line_item|
      # Skip this line item unless it's associated with the target product.
      
      next unless !line_item.properties.key?('gcm_recipient_email')
      # Using the Discount instance, calculate the discount for this line item.
      line_discount = @discount.calculate(line_item)
    

      # Calculated the discounted line price using the line discount.
      new_line_price = line_item.line_price - line_discount

      # Apply the new line price to this line item with a given message
      # describing the discount, which may be displayed in cart pages and
      # confirmation emails to describe the applied discount.
      line_item.change_line_price(new_line_price, message: @message)

      # Print a debugging line to the console.
      puts "Discounted line item with variant #{line_item.variant.id} by #{line_discount}."
      @bundle_count = @bundle_count - 1 * line_item.quantity

     
    end
  end
end

if Input.cart.discount_code
  code = Input.cart.discount_code
  #Input.cart.discount_code.reject(message:'Gift Card Discount applied')
end

# Use an array to keep track of the discount campaigns desired.
CAMPAIGNS = [
  BundleDiscountCampaign.new(
    '',
    Input.cart.discount_code,
    "Gift Card Check",
  ),
]

if code
  puts code
    # Iterate through each of the discount campaigns.
  CAMPAIGNS.each do |campaign|
    # Apply the campaign onto the cart.
    campaign.run(Input.cart)
  end
end

# In order to have the changes to the line items be reflected, the output of
# the script needs to be specified.
Output.cart = Input.cart