internetee-registry/app/models/concerns/invoice/cancellable.rb

module Invoice::Cancellable
  extend ActiveSupport::Concern

  included do
    scope :non_cancelled, -> { where(cancelled_at: nil) }
  end

  def cancellable?
    unpaid? && not_cancelled?
  end

  def cancel
    raise 'Invoice cannot be cancelled' unless cancellable?
    update!(cancelled_at: Time.zone.now)
  end

  def cancelled?
    cancelled_at.present?
  end

  def not_cancelled?
    !cancelled?
  end
end