class OrderPromotionCode < ApplicationRecord
  # Associations
  belongs_to :order
  belongs_to :promotion_code

  # Validations
  validates :order, presence: true
  validates :promotion_code, presence: true

  # Callbacks
  after_create :apply_discount
  after_create :increment_promotion_code_uses

  private

  def apply_discount
    # Apply the discount to the order
    discount_amount = promotion_code.discount_amount_cents
    order.update!(total_amount_cents: [ order.total_amount_cents - discount_amount, 0 ].max)
  end

  def increment_promotion_code_uses
    # Increment the uses count on the promotion code
    promotion_code.increment!(:uses_count)
  end
end