activity.rb

  def mail
    if !activity_type.public || activity_type.private_fields.count > 0
      ActivityMailer.delay.report(id, true)
    end
    if activity_type.public
      public_fields = self.values.select { |value| value.field.public && !value.blank? }
      ActivityMailer.delay.report(id, false) unless public_fields.empty?
    end
  end