/**
  * @param IEntity $subject
  * @throws InvalidArgumentException
  * @return void
  */
 public function send(IEntity $subject)
 {
     if (!$subject instanceof ISurvey) {
         return;
     }
     $current_step = $subject->currentStep();
     $template = $current_step->template();
     if (!$template instanceof ISurveyThankYouStepTemplate) {
         return;
     }
     $owner = $subject->createdBy();
     $to = $owner->getEmail();
     $from = defined('SURVEY_THANK_U_FROM_EMAIL') ? SURVEY_THANK_U_FROM_EMAIL : Config::inst()->get('Email', 'admin_email');
     $email = EmailFactory::getInstance()->buildEmail($from, $to);
     $email->setUserTemplate('survey-builder-thank-you-step')->populateTemplate(array('Member' => $owner))->send();
 }