public override void OnAuthorization(HttpActionContext actionContext)
 {
     if (actionContext.Request.Headers.Contains(Constants.AuthenticationHeaderName))
     {
         var maybeApiKey = actionContext.Request.Headers.GetValues(Constants.AuthenticationHeaderName).ToList();
         if (maybeApiKey.Count() != 1)
         {
             actionContext.Response =
                 new HttpResponseMessage(System.Net.HttpStatusCode.BadRequest);
         }
         else
         {
             if (!_apiKeyRepository.IsValid(maybeApiKey.First()))
             {
                 actionContext.Response =
                     new HttpResponseMessage(System.Net.HttpStatusCode.Forbidden);
             }
         }
     }
     else
     {
         actionContext.Response =
             new HttpResponseMessage(System.Net.HttpStatusCode.BadRequest);
     }
 }