/**
  * @param SS_HTTPRequest $r
  */
 public function presentations(SS_HTTPRequest $r)
 {
     $data = [];
     $speaker = null;
     $key = $r->getVar('key');
     if ($key) {
         $username = PresentationSpeaker::hash_to_username($key);
         $speaker = PresentationSpeaker::get()->filter('Member.Email', $username)->first();
     } elseif ($speakerID = Session::get('UploadMedia.SpeakerID')) {
         $speaker = PresentationSpeaker::get()->byID($speakerID);
     }
     // Speaker not found
     if (!$speaker) {
         return $this->httpError(404, 'Sorry, that does not appear to be a valid token.');
     }
     Session::set('UploadMedia.SpeakerID', $speaker->ID);
     $mostRecentSummit = Summit::get_most_recent();
     $presentations = $speaker->PublishedPresentations($mostRecentSummit->ID);
     // No presentations
     if (!$presentations->exists()) {
         return $this->httpError(404, 'Sorry, it does not appear that you have any presentations.');
     }
     // IF there's only one presentation with no media, go ahead and forward to it's page
     if ($presentations->count() == 1) {
         $slide = $presentations->first()->MaterialType('PresentationSlide');
         if (!$slide) {
             $presentationID = $presentations->first()->ID;
             return $this->redirect(Controller::join_links($this->Link(), '/presentation/', $presentationID, 'upload'));
         }
     }
     $data['Speaker'] = $speaker;
     $data['Presentations'] = $presentations;
     return $this->customise($data);
 }