private static string ValidateNotNullOrEmpty()

in src/Google.Cloud.Functions.Framework/GcfEvents/GcfConverters.cs [159:221]
38 lines of code
2 McCabe index (conditional complexity)

        private static string ValidateNotNullOrEmpty(string? value, string name) =>
            string.IsNullOrEmpty(value)
            ? throw new ConversionException($"Event contained no {name}")
            : value;

        /// <summary>
        /// An event-specific adapter, picked based on the event type from the GCF event.
        /// This class provides seams for event-specific changes to the data and the source/subject,
        /// but the defult implementations of the seams are reasonable for most events.
        /// </summary>
        private class EventAdapter
        {
            private readonly string _cloudEventType;
            private readonly string _defaultService;

            internal EventAdapter(string cloudEventType, string defaultService) =>
                (_cloudEventType, _defaultService) = (cloudEventType, defaultService);

            internal CloudEvent ConvertToCloudEvent(Request request, CloudEventFormatter formatter)
            {
                MaybeReshapeData(request);

                var context = request.Context;
                var resource = context.Resource;
                // Default the service name if necessary
                resource.Service = ValidateNotNullOrEmpty(resource.Service ?? _defaultService, "service");
                ValidateNotNullOrEmpty(resource.Name, "resource name");

                var evt = new CloudEvent
                {
                    Type = _cloudEventType,
                    Id = context.Id,
                    Time = context.Timestamp,
                    DataContentType = JsonContentType
                };
                PopulateAttributes(request, evt);
                var bytes = JsonSerializer.SerializeToUtf8Bytes(request.Data);
                formatter.DecodeBinaryModeEventData(bytes, evt);
                return evt;
            }

            protected virtual void MaybeReshapeData(Request request) { }

            /// <summary>
            /// Populate the attributes in the CloudEvent that can't always be determined directly.
            /// In particular, this method must populate the Source context attribute,
            /// should populate the Subject context attribute if it's defined for this event type,
            /// and should populate any additional extension attributes to be compatible with Eventarc.
            /// The resource within context of the request will definitely have its Service and Name properties populated.
            /// This base implementation populates the Source based on the service and resource.
            /// </summary>
            /// <param name="request">The incoming request. The request's context always has a resource, and the service and name
            /// are always populated by the time this method is called.</param>
            /// <param name="evt">The event to populate</param>
            protected virtual void PopulateAttributes(Request request, CloudEvent evt)
            {
                var service = request.Context.Resource.Service!;
                var resource = request.Context.Resource.Name!;
                evt.Source = FormatSource(service, resource);
            }

            protected Uri FormatSource(string service, string resource) => new Uri($"//{service}/{resource}", UriKind.RelativeOrAbsolute);
        }