public static async Task ProcessFormFile()

in Webapp/SDAF/Controllers/Helper.cs [257:343]
67 lines of code
10 McCabe index (conditional complexity)

        public static async Task<byte[]> ProcessFormFile(IFormFile formFile,
            ModelStateDictionary modelState, string[] permittedExtensions,
            long sizeLimit)
        {
            var fieldDisplayName = "";

            // Use reflection to obtain the display name for the model
            // property associated with this IFormFile. If a display
            // name isn't found, error messages simply won't show
            // a display name.
            MemberInfo property =
                typeof(FileUploadModel).GetProperty(
                    formFile.Name[(formFile.Name.IndexOf(".", StringComparison.Ordinal) + 1)..]);

            if (property != null)
            {
                if (property.GetCustomAttribute(typeof(DisplayAttribute)) is DisplayAttribute displayAttribute)
                {
                    fieldDisplayName = $"{displayAttribute.Name} ";
                }
            }

            // Don't trust the file name sent by the client. To display
            // the file name, HTML-encode the value.
            var trustedFileNameForDisplay = WebUtility.HtmlEncode(formFile.FileName);

            // Check the file length. This check doesn't catch files that only have
            // a BOM as their content.
            if (formFile.Length == 0)
            {
                modelState.AddModelError(formFile.Name,
                    $"{fieldDisplayName}({trustedFileNameForDisplay}) is empty.");

                return Array.Empty<byte>();
            }

            if (formFile.Length > sizeLimit)
            {
                var megabyteSizeLimit = sizeLimit / 1048576;
                modelState.AddModelError(formFile.Name,
                    $"{fieldDisplayName}({trustedFileNameForDisplay}) exceeds " +
                    $"{megabyteSizeLimit:N1} MB.");

                return Array.Empty<byte>();
            }
            Regex rx = new(@"^\w{0,5}-\w{4}-\w{0,7}-\w{0,15}\.tfvars$");
            if (!rx.IsMatch(formFile.FileName))
            {
                modelState.AddModelError(formFile.Name,
                    $"{fieldDisplayName}({trustedFileNameForDisplay}) is named incorrectly");

                return Array.Empty<byte>();
            }

            try
            {
                using var memoryStream = new MemoryStream();
                await formFile.CopyToAsync(memoryStream);

                // Check the content length in case the file's only
                // content was a BOM and the content is actually
                // empty after removing the BOM.
                if (memoryStream.Length == 0)
                {
                    modelState.AddModelError(formFile.Name,
                        $"{fieldDisplayName}({trustedFileNameForDisplay}) is empty.");
                }

                if (!IsValidFileExtension(formFile.FileName, memoryStream, permittedExtensions))
                {
                    modelState.AddModelError(formFile.Name,
                        $"{fieldDisplayName}({trustedFileNameForDisplay}) file type isn't permitted.");
                }
                else
                {
                    return memoryStream.ToArray();
                }
            }
            catch (Exception ex)
            {
                modelState.AddModelError(formFile.Name,
                    $"{fieldDisplayName}({trustedFileNameForDisplay}) upload failed. " +
                    $"Please contact the Help Desk for support. Error: {ex.HResult}");
            }

            return Array.Empty<byte>();
        }