FileUploader

public interface IFileUploader
	{
		Task<FileInfo> GetUploadedFile(HttpContent content, string expectedExtension);
	}

	public class FileUploader : IFileUploader
	{
		public async Task<FileInfo> GetUploadedFile(HttpContent content, string expectedExtension)
		{
			if (!content.IsMimeMultipartContent())
			{
				throw new HttpResponseException(HttpStatusCode.UnsupportedMediaType);
			}

			var root = ImportExportApplication.FindTemporaryDirectory();

			var provider = new MultipartFormDataStreamProvider(root);

			await content.ReadAsMultipartAsync(provider);

			MultipartFileData file = provider.FileData.FirstOrDefault();
			if (file == null)
			{
				throw new FileNotFoundException();
			}

			var extension = Path.GetExtension(file.Headers.ContentDisposition.FileName.Trim('/', '"'));
			if (extension != expectedExtension)
			{
				throw new InvalidOperationException(Resources.BadFileFormat);
			}

			return new FileInfo(Path.Combine(root, file.LocalFileName.Trim('/', '"')));
		}
	}