Prioritize original transfer syntax when multiple accepts with no quality provided (#2753)

## Description
SLIM viewer sends multiple accept headers to get frames. Original is the
last, this causes us to pick another accept and fail because today our
code needs entire file to do transcoding and will throw when file size
is greater than 100M.

This fix will make us prioritize picking original if available in the
accept list.

## Related issues
ImagingDataCommons/dicom-microscopy-viewer#95

## Testing
Added unit tests

---------

Co-authored-by: smithasa <smithasa@SMITHASAMI1>

Author: smithago

src/Microsoft.Health.Dicom.Core.UnitTests/Features/Retrieve/AcceptHeaderHandlerTests.cs

@@ -5,11 +5,13 @@
 
 using System.Collections.Generic;
 using System.Linq;
+using FellowOakDicom;
 using Microsoft.Extensions.Logging.Abstractions;
 using Microsoft.Health.Dicom.Core.Exceptions;
 using Microsoft.Health.Dicom.Core.Features.Retrieve;
 using Microsoft.Health.Dicom.Core.Messages;
 using Microsoft.Health.Dicom.Core.Messages.Retrieve;
+using Microsoft.Health.Dicom.Core.Web;
 using Xunit;
 
 namespace Microsoft.Health.Dicom.Core.UnitTests.Features.Retrieve;
@@ -139,7 +141,7 @@ public void
         AcceptHeader requestedAcceptHeader1 = new AcceptHeader(
             ValidStudyAcceptHeaderDescriptor.MediaType,
             ValidStudyAcceptHeaderDescriptor.PayloadType,
-            ValidStudyAcceptHeaderDescriptor.AcceptableTransferSyntaxes.First(),
+            DicomTransferSyntaxUids.Original,
             quality: 0.3
         );
 
@@ -164,4 +166,26 @@ public void
 
         Assert.Equivalent(requestedAcceptHeader2, matchedAcceptHeader, strict: true);
     }
+
+    [Fact]
+    public void GivenMultipleMatchedAcceptHeaderNoQuality_WhenTransferSyntaxRequested_ThenShouldReturnOriginal()
+    {
+        AcceptHeader requestedAcceptHeader1 = new AcceptHeader(
+                payloadType: PayloadTypes.MultipartRelated,
+                mediaType: KnownContentTypes.ImageJpeg2000,
+                transferSyntax: DicomTransferSyntax.JPEG2000Lossless.UID.UID);
+
+        AcceptHeader requestedAcceptHeader2 = new AcceptHeader(
+                payloadType: PayloadTypes.SinglePart,
+                mediaType: KnownContentTypes.ApplicationOctetStream,
+                transferSyntax: DicomTransferSyntaxUids.Original);
+
+
+        AcceptHeader matchedAcceptHeader = _handler.GetValidAcceptHeader(
+            ResourceType.Frames,
+            new[] { requestedAcceptHeader1, requestedAcceptHeader2 }
+        );
+
+        Assert.Equivalent(requestedAcceptHeader2, matchedAcceptHeader, strict: true);
+    }
 }

src/Microsoft.Health.Dicom.Core/Features/Retrieve/AcceptHeaderHandler.cs

@@ -59,7 +59,7 @@ private AcceptHeaderHandler(
     public AcceptHeader GetValidAcceptHeader(ResourceType resourceType, IReadOnlyCollection<AcceptHeader> acceptHeaders)
     {
         EnsureArg.IsNotNull(acceptHeaders, nameof(acceptHeaders));
-        List<AcceptHeader> orderedHeaders = acceptHeaders.OrderByDescending(x => x.Quality).ToList();
+        List<AcceptHeader> orderedHeaders = acceptHeaders.OrderByDescending(x => x.Quality ?? AcceptHeader.DefaultQuality).ToList();
 
         _logger.LogInformation(
             "Getting transfer syntax for retrieving {ResourceType} with accept headers {AcceptHeaders}.",
@@ -68,26 +68,42 @@ public AcceptHeader GetValidAcceptHeader(ResourceType resourceType, IReadOnlyCol
 
         List<AcceptHeaderDescriptor> descriptors = _acceptableDescriptors[resourceType];
 
-        // since these are ordered by quality already, we can return the first acceptable header
+        AcceptHeader selectedHeader = null;
+        // we will return the highest priority media type we support
         foreach (AcceptHeader header in orderedHeaders)
         {
             foreach (AcceptHeaderDescriptor descriptor in descriptors)
             {
-                if (descriptor.IsAcceptable(header))
+                if (descriptor.IsAcceptable(header) && (selectedHeader == null || IsHigherPriorityTransferSyntax(header, selectedHeader)))
                 {
-                    return new AcceptHeader(
+                    selectedHeader = new AcceptHeader(
                         header.MediaType,
                         header.PayloadType,
                         descriptor.GetTransferSyntax(header),
                         header.Quality);
+
+                    continue;
                 }
             }
         }
 
+        if (selectedHeader != null)
+        {
+            _logger.LogInformation("Selected accept header {AcceptHeader} for retrieving {ResourceType}.", selectedHeader, resourceType);
+            return selectedHeader;
+        }
+
         //  none were valid
         throw new NotAcceptableException(DicomCoreResource.NotAcceptableHeaders);
     }
 
+    // if no quality provided prioritize returning original transfer syntax
+    private static bool IsHigherPriorityTransferSyntax(AcceptHeader header, AcceptHeader selectedHeader)
+    {
+        bool isQualityGreater = (header.Quality ?? AcceptHeader.DefaultQuality) >= (selectedHeader.Quality ?? AcceptHeader.DefaultQuality);
+        return (header.TransferSyntax.Value == DicomTransferSyntaxUids.Original && isQualityGreater);
+    }
+
     private static List<AcceptHeaderDescriptor> DescriptorsForGetNonFrameResource(PayloadTypes payloadTypes)
     {
         return new List<AcceptHeaderDescriptor>

src/Microsoft.Health.Dicom.Core/Messages/Retrieve/AcceptHeader.cs

@@ -1,4 +1,4 @@
-// -------------------------------------------------------------------------------------------------
+// -------------------------------------------------------------------------------------------------
 // Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT License (MIT). See LICENSE in the repo root for license information.
 // -------------------------------------------------------------------------------------------------