Added first draft of recovery logic

middleware/app_be/views/rest_api.py

@@ -51,27 +51,54 @@ class ImageEndpoint:
         # get stored SHA512 hash
         stored_hash = metadata.get('sha512', '')
         logger.debug('Sorted SHA512: {}'.format(stored_hash))
-        service_image_bytes = None
+        # recovery code
+        recovery_has_image = {}
+        recovery_hash_matches = {}
+        valid_image_bytes = None
+        # check image existence and correctness for each service + retrieve valid image if possible
         for service in ImageEndpoint.storageServiceList:
-            logger.debug('Checking hash for ' + service.name)
+            logger.debug('Checking recovery for service ' + service.name)
-            # get image bytes from Dropbox
+            print('Checking recovery for service ' + service.name)
             service_image_bytes = service.read_file(metadata['filename'])
-            if service_image_bytes is None:
+            if service_image_bytes is not None:
-                return JsonResponse({'Result': 'Error - could not find image in ' + service.name, 'id': identifier},
+                recovery_has_image[service.name] = True
-                                    status=404, safe=False)
+                actual_service_hash = create_sha512(service_image_bytes)
+                if stored_hash == actual_service_hash:
+                    recovery_hash_matches[service.name] = True
+                    if valid_image_bytes is None:
+                        valid_image_bytes = service_image_bytes
+                else:
+                    recovery_hash_matches[service.name] = False
+            else:
+                recovery_has_image[service.name] = False
+                recovery_hash_matches[service.name] = False
 
-            # calc dropbox image hash
+        # TODO: after talking with tobias about updating => replace with older version if hash is wrong
-            actual_service_hash = create_sha512(service_image_bytes)
+
-            logger.debug('Actual '+service.name+' SHA512: {}'.format(actual_service_hash))
+        # check if any service has the image saved
-            if stored_hash != actual_service_hash:
+        if not ImageEndpoint.combine_boolean_dict_or(recovery_has_image):
-                return JsonResponse('Stored hash in service "'+service.name+'"does not match generated one! '
+            logger.debug('None of the storage services has the requested image saved')
-                                    'stored: {} actual: {}'.format(stored_hash, actual_service_hash),
+            MongoDBService.deleteSingle(identifier)
-                                    status=400, safe=False)
+            return JsonResponse({'Result': 'Error - image is not available on any storage service and was deleted',
+                                 'id': identifier}, status=404, safe=False)
+
+        # check if any service has a valid version of the image saved
+        if not ImageEndpoint.combine_boolean_dict_or(recovery_hash_matches) and valid_image_bytes is None:
+            logger.debug('None of the storage services has a valid image saved')
+            MongoDBService.deleteSingle(identifier)
+            return JsonResponse({'Result': 'Error - image is not available on any storage service and was deleted',
+                                 'id': identifier}, status=404, safe=False)
+
+        # at this point we know at least one valid image is available
+        for service in ImageEndpoint.storageServiceList:
+            if not recovery_has_image[service.name] or not recovery_hash_matches[service.name]:
+                if not service.create_file(metadata['filename'], valid_image_bytes):
+                    logger.error('Error duplicating file in service ' + service.name)
 
         payload = {
             'id': identifier,
             'metadata': metadata,
-            'image_data': WrapperService.wrap_file(service_image_bytes)
+            'image_data': WrapperService.wrap_file(valid_image_bytes)
         }
 
         return JsonResponse(payload, safe=False)
@@ -175,6 +202,20 @@ class ImageEndpoint:
         return JsonResponse({'id': identifier, 'filename': filename},
                             safe=False)
 
+    @staticmethod
+    def combine_boolean_dict_and(d: dict) -> bool:
+        result = True
+        for entry in d:
+            result = (result and d[entry])
+        return result
+
+    @staticmethod
+    def combine_boolean_dict_or(d: dict) -> bool:
+        result = False
+        for entry in d:
+            result = (result or d[entry])
+        return result
+
 
 class HealthEndpoint: