implement registration in backend

common/models/EventType.php

@@ -89,7 +89,19 @@ class EventType extends \yii\db\ActiveRecord
         if ( sizeof($tickets) == 0 ){
             return null;
         }
+        $possibleTickets = [];
+
+        foreach ($tickets as $ticket ){
+            if ( $ticket->hasOpenReservationCount() ){
+                $possibleTickets[] = $ticket;
+            }
+        }
+
+        if ( sizeof($possibleTickets) == 0 ){
+            return null;
+        }
+
         // TODO: implement bossiness logic to select ticket
-        return $tickets[0];
+        return $possibleTickets[0];
     }
 }