Updating view for different certificate statuses, error

lms/djangoapps/certificates/views.py

 import logging
 from certificates.models import GeneratedCertificate
+from certificates.models import CertificateStatuses as status
 from django.views.decorators.csrf import csrf_exempt
 from django.http import HttpResponse
 import json
 
-log = logging.getLogger("mitx.certificates")
+logger = logging.getLogger(__name__)
 
 
 @csrf_exempt
@@ -12,6 +13,10 @@ def update_certificate(request):
     """
     Will update GeneratedCertificate for a new certificate or
     modify an existing certificate entry.
+
+    See models.py for a state diagram of certificate states
+
+    This view should only ever be accessed by the xqueue server
     """
 
     if request.method == "POST":
@@ -26,7 +31,7 @@ def update_certificate(request):
                    key=xqueue_header['lms_key'])
 
         except GeneratedCertificate.DoesNotExist:
-            log.critical('Unable to lookup certificate\n'
+            logger.critical('Unable to lookup certificate\n'
                          'xqueue_body: {0}\n'
                          'xqueue_header: {1}'.format(
                                       xqueue_body, xqueue_header))
@@ -36,10 +41,23 @@ def update_certificate(request):
                             'content': 'unable to lookup key'}),
                              mimetype='application/json')
 
-        cert.download_uuid = xqueue_body['download_uuid']
-        cert.verify_uuid = xqueue_body['download_uuid']
-        cert.download_url = xqueue_body['url']
-        cert.status = 'downloadable'
+        if 'error' in xqueue_body:
+            cert.status = status.error
+        else:
+            if cert.state in [status.generating, status.regenerating]:
+                cert.download_uuid = xqueue_body['download_uuid']
+                cert.verify_uuid = xqueue_body['verify_uuid']
+                cert.download_url = xqueue_body['url']
+                cert.status = status.downloadable
+            elif cert.state in [status.deleting]:
+                cert.status = status.deleted
+            else:
+                logger.critical('Invalid state for cert update: {0}'.format(
+                    cert.state))
+                return HttpResponse(json.dumps({
+                            'return_code': 1,
+                            'content': 'invalid cert state'}),
+                             mimetype='application/json')
         cert.save()
         return HttpResponse(json.dumps({'return_code': 0}),
                              mimetype='application/json')