class ParentNotifier
  def initialize(klass)
    @klass = klass
  end

  def notify_when_finished(collection = nil)
    collection ||= objects_pending_notification
    collection.each(&:notify_parent)
  end

  def objects_pending_notification
    @klass
      .where(
        notified_parent_at: nil,
        status: @klass.finished_statuses
      )
      .where.not(parent: nil)
  end
end