survey_inviter.rb

class SurveyInviter
  def initialize(attributes = {})
    @survey_manager = SurveyManager.new(
      Survey.new(attributes[:survey]),
      Sender.new(attributes[:sender])
    )
    @message_manager = MessageManager.new(
      Message.new(attributes[:message]),
      Recipients.new(attributes[:recipients])
    )
  end

  def valid?
    message_manager.valid?
  end

  def deliver
    message_manager.all_recipients do |recipient|
      Mailer.invitation_notification(invitation(recipient), message_manager.message)
    end
  end

  private
  def invitation(email)
    Invitation.create(invitation_params(email))
  end

  def invitation_params(email)
    @survey_manager.params.merge({
      recipient_email: email,
      status: 'pending'
    })
  end
end

class MessageManager
  def initialize(message, recipients)
    @message = message
    @recipients = recipients
    freeze
  end

  def all_recipients(&block)
    @recipients.each(&block)
  end

  def valid?
    is_message_valid? && are_recipients_valid?
  end

  def is_message_valid?
    @message.valid?
  end

  def are_recipients_valid?
    @recipients.valid?
  end

  def message
    @message.to_s
  end

end

class SurveyManager
  def initialize(survey, sender)
    @survey = survey
    @sender = sender
    freeze
  end

  def survey
    @survey.to_s
  end

  def sender
    @sender.to_s
  end

  def params
    {
      survey: @survey,
      sender: @sender
    }
  end
end