public async Task GetFieldValues()

in packages/ekyc-api/src/ekyc-api/Controllers/DataController.cs [120:190]
50 lines of code
10 McCabe index (conditional complexity)

        public async Task<string> GetFieldValues(S3DataRequest request)
        {
            AWSXRayRecorder.Instance.BeginSubsegment("DataController:GetFieldValues");

            if (request == null)
                throw new HttpStatusException(HttpStatusCode.BadRequest, "Request cannot be blank.");

            var manager = new DataRequestManager(_config, _amazonS3, _dynamoDb);

            if (request.RequestId == null ||
                !manager.DataRequestExistsAndIsValid(request.RequestId).GetAwaiter().GetResult())
                throw new HttpStatusException(HttpStatusCode.BadRequest,
                    "Request is invalid - did you create a new request first?");

            if (string.IsNullOrEmpty(request.s3Key))
                throw new HttpStatusException(HttpStatusCode.BadRequest, "S3Key cannot be blank.");


            DocumentTypes docType;

            var s3Key = request.RequestId + "/" + request.s3Key;

            if (!string.IsNullOrEmpty(request.documentType))
            {
                if (!Enum.TryParse(request.documentType, out docType))
                    throw new HttpStatusException(HttpStatusCode.BadRequest,
                        $"{request.documentType} is not a valid document type.");
            }

            else
            {
                var detectResponse = await new Imaging(_amazonS3, _documentChecker).DetectAndCropDocument(s3Key);

                // The detection may fail because there isn't a Rekognition Custom Labels project running, or it hasn't been trained
                if (detectResponse.HasValue)
                {
                    // We may need to crop out the background by detecting the bounding box of the document

                    // Save the cropped image to S3
                    s3Key = request.RequestId + "/" + Guid.NewGuid().ToString() + ".png";

                    await _amazonS3.PutObjectAsync(new PutObjectRequest()
                    {
                        BucketName = Globals.StorageBucket,
                        AutoCloseStream = true,
                        Key = s3Key,
                        InputStream = detectResponse.Value.CroppedImage
                    });

                    docType = detectResponse.Value.documentType;
                }
                else
                {
                    if (string.IsNullOrEmpty(request.documentType))
                        throw new HttpStatusException(HttpStatusCode.BadRequest,
                            "Unable to infer document type, so DocumentType in the request cannot be blank.");

                    if (!Enum.TryParse(request.documentType, out docType))
                        throw new HttpStatusException(HttpStatusCode.BadRequest,
                            $"{request.documentType} is not a valid document type.");
                }
            }

            var documentDefinition = await _factory.GetDocumentDefinition(docType);

            var fieldData = await documentDefinition.GetFieldData(s3Key, docType);

            AWSXRayRecorder.Instance.EndSubsegment();

            return JsonSerializer.Serialize(fieldData);
        }