diff --git a/src/controller/DiagramController.php b/src/controller/DiagramController.php
index 3fbe80a..6bb4aef 100644
--- a/src/controller/DiagramController.php
+++ b/src/controller/DiagramController.php
@@ -1,470 +1,459 @@
 <?php
 
 final class DiagramController extends PhabricatorController {
   /**
    * Processes incoming HTTP requests from Diagram application
    */
   public function handleRequest(AphrontRequest $request) {
 
     $this->setRequest($request);
 
     // detetermine if GET or POST HTTP call
     if ($request->isHTTPPost()) {
       // process POST calls (like save action)
       return $this->handleHttpPostCall($request);
     }
 
     // determine type of URL by means of DiagramApplication route parameters
     $diagramid = $request->getURIData('diagramid');
     $versioneddiagramid = $request->getURIData('versioneddiagramid');
     $version = $request->getURIData('version');
     $route = $request->getURIData('route');
     $versioninfoDiagramID = $request->getURIData('versioninfodiagram');
     $versioninfoPage = $request->getURIData('versioninfopage');
 
-    if (isset($diagramphid) && !empty(trim($diagramphid))) {
-      // return PNG image data
-      $diagram = id(new DiagramVersion())->loadByDiagramPHID($diagramphid);
-      if ($diagram !== null) {
-        $response = new AphrontFileResponse();
-        $response->setMimeType('image/png');
-        $response->setContent($diagram->getData());
-        return $response;
-      }
-    }
-
     if (isset($versioninfoDiagramID) && !empty(trim($versioninfoDiagramID))) {
       // return diagram version info
       if (!isset($versioninfoPage) || empty(trim($versioninfoPage))) {
         // versioninfoPage was dismissed -> initialize to 1
         $versioninfoPage = '1';
       }
 
       $diagramVersions = id(new DiagramVersion())->loadByDiagramID(
         $versioninfoDiagramID);
 
       if ($diagramVersions !== null) {
         $result = [];
         $viewer = $request->getViewer();
 
         // determine total count of versions
         $totalcount = count($diagramVersions);
 
         // filter out some of the versions we want to show
         $pageSize = 10;
         $diagramVersions = array_slice(
           $diagramVersions,
           ($versioninfoPage - 1) * $pageSize,
           $pageSize
         );
 
         // calculate number of pages
         $totalpages = ceil($totalcount / $pageSize);
 
         // create menu-items
         foreach ($diagramVersions as $diagramVersion) {
           $author = $diagramVersion->getAuthorPHID();
 
           $user = id(new PhabricatorPeopleQuery())
             ->setViewer($viewer)
             ->withPHIDs(array(
               $author
             ))
             ->executeOne();
 
           $dateModified = $diagramVersion->getDateModified();
 
           $result[] = array(
             'id' => $diagramVersion->getVersion(),
             'datetime' => phabricator_datetime($dateModified, $viewer),
             'author' => $user->getUsername()
           );
         }
 
         // reply back
         $response = id(new AphrontJSONResponse())->setAddJSONShield(false)
           ->setContent(array(
             'data' => $result,
             'pagecount' => $totalpages,
             'nopager' => $totalcount <= $pageSize
           ));
         return $response;
       } else {
         // version info requested for inexistant diagram
         $response = id(new AphrontJSONResponse())->setAddJSONShield(false)
           ->setContent(array(
             'data' => array(),
             'pagecount' => 0
           ));
         return $response;
       }
     }
 
     $root = '';
     $file = rtrim($request->getPath(), '/');
     $root = dirname(phutil_get_library_root('diagram'));
 
     // determine from which application area the file should be loaded:
     //    1) Phorge extension source
     // or 2) drawio source
     if ($route == 'iframe') {
       // load from drawio source
       if ($file == '/diagram/iframe')
         $file .= '/index.html';
       if ($versioneddiagramid != null && $version != null) {
         $file = preg_replace(
           '/^\/diagram\/' . $versioneddiagramid . '\/'. $version . 'iframe\//',
           'drawio/src/main/webapp/',
           $file);
       } else {
         $file = preg_replace("/^\/diagram\/($diagramid\/?)?iframe\//",
           'drawio/src/main/webapp/',
           $file);
       }
     } else {
       // load from extension source
       if (rtrim($file, '/') == '/diagram') {
         return $this->showApplication();
       }
 
       if ($versioneddiagramid !== null && $version !== null) {
         $file = preg_replace(
           '/^\/diagram\/' . $versioneddiagramid . '\/'. $version . '\/?/',
           'data/',
           $file
         );
         $file = rtrim($file, '/') . '/' . $versioneddiagramid;
       } else {
         $file = preg_replace(
           '/^\/diagram\/(' . $diagramid . '\/)?/',
           'data/',
           $file
         );
       }
     }
 
     // determine full path
     $path = $root . '/' . $file;
 
     if (file_exists($path) == false || is_readable($path) == false) {
       if (preg_match('/^data\/DIAG(\d+)$/', $file, $matches)) {
         $diagram_id = (int) $matches[1];
         if ($version === null) {
           $diagramVersion = id(new DiagramVersion())->loadLatestByDiagramID(
             $diagram_id);
         } else {
           $diagramVersion = id(new DiagramVersion())->loadByVersionedDiagramID(
             $diagram_id, $version);
         }
         if ($diagramVersion) {
           $data = $diagramVersion->getData();
           $base64_data = base64_encode($data);
 
           $diagram = id(new Diagram())->loadByID($diagram_id);
 
           return $this->showApplication(
             'DIAG' . $diagram_id,
             $diagram->getPHID(),
             $version ?? '',
             $base64_data
           );
         }
       }
 
       // Invalid URL
       $response = id(new Aphront404Response());
       return $response;
     } else {
       // process Iframe content
       switch (pathinfo($file, PATHINFO_EXTENSION)) {
         case 'html':
           $response = id(new PlainHtmlWebpageResponse())
             ->setDisableContentSecurityPolicy(true)
             ->setFrameable(true)
             ->setContent(file_get_contents($path));
           break;
         case 'js':
           $response = new AphrontFileResponse();
           $response->setMimeType('application/javascript');
           break;
         case 'css':
           $response = new AphrontFileResponse();
           $response->setMimeType('text/css');
           break;
         case 'txt':
           $response = new AphrontFileResponse();
           $response->setMimeType('text/plain');
           break;
         case 'png':
           $response = new AphrontFileResponse();
           $response->setMimeType('image/png');
           break;
         case 'gif':
           $response = new AphrontFileResponse();
           $response->setMimeType('image/gif');
           break;
         case 'jpg':
         case 'jpeg':
           $response = new AphrontFileResponse();
           $response->setMimeType('image/jpeg');
           break;
         default:
           $response = new AphrontFileResponse();
           $response->setMimeType('application/octet-stream');
           break;
       }
       try {
         $response->setContent(file_get_contents($path));
         $response->setCacheDurationInSeconds(60 * 60 * 24 * 30);
         $response->setLastModified(time());
         $response->setCanCDN(true);
       } catch (Exception $e) {
         $response->setContent($route);
       }
       return $response;
     }
   }
 
   /**
    * Compares the draw.io tEXt metadata from 2 PNG base64 strings.
    * The content looks like this:
    * <mxfile host="..." modified="..." agent="..." etag="..." version="..."...>
    *  <diagram id="O253AQcHVgjdl_wygdBA" name="Page-1">
    *    <mxGraphModel ...>
    *     <root>
    *      ...
    *     </mxCell>
    *    </root>
    *   </mxGraphModel>
    *  </diagram>
    * </mxfile>
    *
    * The modified and etag attributes of mxfile will always be different.
    * They are cut out before the 2 strings are compared.
    */
   public static function equalPngMetaData($base64_1, $base64_2) {
     $base64 = array($base64_1, $base64_2);
     $textData = array();
     for ($i = 0; $i < 2; $i++) {
       $data = base64_decode($base64[$i]);
       $fp = fopen('data://text/plain;base64,' . base64_encode($data), 'rb');
       $sig = fread($fp, 8);
       if ($sig != "\x89PNG\x0d\x0a\x1a\x0a") {
         fclose($fp);
         return false;
       }
       $textData[$i] = array();
       while (!feof($fp)) {
         try {
           $chunk = unpack('Nlength/a4type', fread($fp, 8));
         } catch (Exception $e) {
           // invalid base64 data
           return false;
         }
         if ($chunk['type'] == 'IEND') break;
         if ($chunk['type'] == 'tEXt') {
           list($key, $val) = explode("\0", fread($fp, $chunk['length']));
           if ($key == 'mxfile') {
             // Decode the URL-encoded XML data
             $decodedVal = urldecode($val);
             // Load the XML and remove the modified and etag attributes
             $xml = simplexml_load_string($decodedVal);
             unset($xml->attributes()->modified);
             unset($xml->attributes()->etag);
             // Save the modified XML as the value
             $val = $xml->asXML();
           }
           $textData[$i][$key] = $val;
           fseek($fp, 4, SEEK_CUR);
         } else {
           fseek($fp, $chunk['length'] + 4, SEEK_CUR);
         }
       }
       fclose($fp);
     }
 
     if (isset($textData[0]['mxfile']) && isset($textData[1]['mxfile'])) {
       // Both arrays contain the mxfile key, compare their values
       return $textData[0]['mxfile'] == $textData[1]['mxfile'];
     } else {
       // At least one of the arrays doesn't contain mxfile key, return false
       return false;
     }
   }
 
   /**
    * Processes HTTP POST calls from Diagram application, like 'Save' action
    */
   private function handleHttpPostCall(AphrontRequest $request) {
     $subscriptionphid = $request->getURIData('subscriptionphid');
 
     if (isset($subscriptionphid) && !empty(trim($subscriptionphid))) {
       // get list of subscriber for specified diagram phid
       $subscribers = PhabricatorSubscribersQuery::loadSubscribersForPHID(
         $subscriptionphid);
 
       // verify if viewer is subscriber
       $viewer = $request->getViewer();
       if ($viewer == null) {
         $isSubscribed = false;
       } else {
         $isSubscribed = in_array($viewer->getPHID(),$subscribers);
       }
 
       // reply back
       $response = id(new AphrontJSONResponse())->setAddJSONShield(false)
         ->setContent(array(
           'subscribed' => $isSubscribed
         ));
       return $response;
     }
 
     $base64_data = $request->getStr('data');
     $diagram_id = $request->getStr('diagramID');
 
     // cut off "data:image/png;base64,"
     $base64_data = substr($base64_data, strpos($base64_data, ',') + 1);
 
     if ($diagram_id != '') {
       // check if we are trying to save the same data as the current data
       $diagram = id(new DiagramVersion())->loadLatestByDiagramID($diagram_id);
       if ($diagram !== null) {
         $data = $diagram->getData();
         $old_data = base64_encode($data);
 
         if (DiagramController::equalPngMetaData($base64_data, $old_data)) {
           // data hasn't been modified
           // => do not create new version
           $response = id(new AphrontJSONResponse())->setAddJSONShield(false)
             ->setContent(array(
               'Status' => 'OK',
               'DiagramID' => $diagram->getDiagramID(),
               'Version' => $diagram->getVersion()
             ));
           return $response;
         }
       }
     }
 
     // Set the options for the new file
     $options = array(
       'name' => 'diagram.png',
       'viewPolicy' => PhabricatorPolicies::POLICY_USER,
       'mime-type' => 'image/png',
       'actor' => $this->getViewer(),
       'diagramID' => $diagram_id
     );
 
     try {
       // Create the new file object
       $diagram = DiagramVersion::newFromFileData($base64_data, $options);
 
       $diagram->publishNewVersion($request, $diagram->getDiagramID());
 
       $response = id(new AphrontJSONResponse())->setAddJSONShield(false)
         ->setContent(array(
           'Status' => 'OK',
           'DiagramID' => $diagram->getDiagramID(),
           'Version' => $diagram->getVersion()
         ));
       return $response;
     } catch (Exception $e) {
       $response = id(new AphrontJSONResponse())->setAddJSONShield(false)
         ->setContent(array(
           'Status' => 'ERROR',
           'Error' => $e->getMessage(),
         ));
       return $response;
     }
   }
 
   /**
    * Verifies if the given base64 data is draw.io compatible
    */
   public static function isDrawioPngBase64($base64) {
     $data = base64_decode($base64);
     $fp = fopen('data://text/plain;base64,' . base64_encode($data), 'rb');
     $sig = fread($fp, 8);
     if ($sig != "\x89PNG\x0d\x0a\x1a\x0a") {
       fclose($fp);
       return false;
     }
     while (!feof($fp)) {
       try {
         $chunk = unpack('Nlength/a4type', fread($fp, 8));
       } catch (Exception $e) {
         // invalid base64 data
         return false;
       }
       if ($chunk['type'] == 'IEND') break;
       if ($chunk['type'] == 'tEXt') {
         list($key, $val) = explode("\0", fread($fp, $chunk['length']));
         if ($key == 'mxfile') {
           fclose($fp);
           return true;
         }
         fseek($fp, 4, SEEK_CUR);
       } else {
         fseek($fp, $chunk['length'] + 4, SEEK_CUR);
       }
     }
     fclose($fp);
     return false;
   }
 
   /**
    * Shows the draw.io application integrated in Phorge's layout
    */
   private function showApplication(
     string $diagramName = '',
     string $diagramPHID = '',
     string $diagramVersion = '',
     string $base64_data = ''
   ) {
     $behaviorConfig = array();
     $behaviorConfig['initParams'] = array(
       $diagramName,
       $diagramPHID,
       $diagramVersion,
       $base64_data
     );
     $behaviorConfig['toolbarCss'] = celerity_get_resource_uri(
       '/iframe-toolbtn.css',
       'diagram-resources'
     );
     $behaviorConfig['toolbarJs'] = celerity_get_resource_uri(
       '/iframe-toolbtn.js',
       'diagram-resources'
     );
 
     require_celerity_resource('javelin-behavior');
     require_celerity_resource('diagram-css-extension', 'diagram-resources');
     Javelin::initBehavior('diagram-extension', $behaviorConfig, 'diagram-resources');
 
     $crumbs = $this->buildApplicationCrumbs()->setBorder(true);
     if (!$diagramName) {
       $crumbs->addTextCrumb('Create Diagram');
     } else {
       $crumbs->addTextCrumb(
         $diagramName,
         $this->getApplicationURI('/' . $diagramName)
       );
 
       if ($diagramVersion) {
         $crumbs->addTextCrumb('Version ' . $diagramVersion);
       }
     }
 
     return $this->newPage()
       ->addClass('diagram-editor-page')
       ->setTitle('Diagrams')
       ->setCrumbs($crumbs)
       ->appendChild(phutil_tag(
         'div',
         array(
           'id' => 'diagram-editor-wrapper'
         )
       ));
   }
 
 }