[StaticWebAssets] Use property for original resource (#50420)

Co-authored-by: Marek Fišera <[email protected]>

Author: javiercn

src/StaticWebAssetsSdk/Targets/Microsoft.NET.Sdk.StaticWebAssets.Compression.targets

@@ -170,7 +170,8 @@ Copyright (c) .NET Foundation. All rights reserved.
     <BrotliCompressionLevel Condition="'$(_BlazorBrotliCompressionLevel)' != ''">$(_BlazorBrotliCompressionLevel)</BrotliCompressionLevel>
 
     <!-- Attach weak ETag to compressed assets -->
-    <AttachWeakETagToCompressedAssetsDuringDevelopment Condition="'$(AttachWeakETagToCompressedAssetsDuringDevelopment)' == '' and '$(Configuration)' == 'Debug'">true</AttachWeakETagToCompressedAssetsDuringDevelopment>
+    <LinkAlternativeRepresentationsToOriginalResource Condition="'$(LinkAlternativeRepresentationsToOriginalResource)' == '' and '$(_TargetingNET100OrLater)' == 'true'">EndpointProperty</LinkAlternativeRepresentationsToOriginalResource>
+    <LinkAlternativeRepresentationsToOriginalResource Condition="'$(LinkAlternativeRepresentationsToOriginalResource)' == ''">ResponseHeader</LinkAlternativeRepresentationsToOriginalResource>
   </PropertyGroup>
 
   <PropertyGroup>
@@ -253,7 +254,7 @@ Copyright (c) .NET Foundation. All rights reserved.
     <ApplyCompressionNegotiation
       CandidateEndpoints="@(StaticWebAssetEndpoint)"
       CandidateAssets="@(_CompressionCurrentProjectBuildAssets)"
-      AttachWeakETagToCompressedAssets="$(AttachWeakETagToCompressedAssetsDuringDevelopment)"
+      AttachWeakETagToCompressedAssets="$(LinkAlternativeRepresentationsToOriginalResource)"
     >
       <Output TaskParameter="UpdatedEndpoints" ItemName="_UpdatedCompressionBuildEndpoints" />
     </ApplyCompressionNegotiation>
@@ -377,7 +378,8 @@ Copyright (c) .NET Foundation. All rights reserved.
 
     <ApplyCompressionNegotiation
       CandidateEndpoints="@(StaticWebAssetEndpoint)"
-      CandidateAssets="@(_CompressionCurrentProjectPublishAssets)">
+      CandidateAssets="@(_CompressionCurrentProjectPublishAssets)"
+      AttachWeakETagToCompressedAssets="$(LinkAlternativeRepresentationsToOriginalResource)">
       <Output TaskParameter="UpdatedEndpoints" ItemName="_UpdatedCompressionPublishEndpoints" />
     </ApplyCompressionNegotiation>
 

src/StaticWebAssetsSdk/Targets/Sdk.StaticWebAssets.CurrentVersion.targets

@@ -43,6 +43,18 @@ Copyright (c) .NET Foundation. All rights reserved.
 
   <!-- Resolve the TFM-specific attributes conditionally. -->
   <Choose>
+    <When Condition=" '$(TargetFrameworkIdentifier)' == '.NETCoreApp' AND $([MSBuild]::VersionGreaterThanOrEquals('$(TargetFrameworkVersion)', '10.0')) ">
+      <PropertyGroup>
+        <_TargetingNETCoreApp30OrLater>true</_TargetingNETCoreApp30OrLater>
+        <_TargetingNET50OrLater>true</_TargetingNET50OrLater>
+        <_TargetingNET60OrLater>true</_TargetingNET60OrLater>
+        <_TargetingNET70OrLater>true</_TargetingNET70OrLater>
+        <_TargetingNET80OrLater>true</_TargetingNET80OrLater>
+        <_TargetingNET90OrLater>true</_TargetingNET90OrLater>
+        <_TargetingNET100OrLater>true</_TargetingNET100OrLater>
+        <_RazorLangVersion Condition="'$(RazorLangVersion)' == '' ">10.0</_RazorLangVersion>
+      </PropertyGroup>
+    </When>
     <When Condition=" '$(TargetFrameworkIdentifier)' == '.NETCoreApp' AND $([MSBuild]::VersionGreaterThanOrEquals('$(TargetFrameworkVersion)', '9.0')) ">
       <PropertyGroup>
         <_TargetingNETCoreApp30OrLater>true</_TargetingNETCoreApp30OrLater>

src/StaticWebAssetsSdk/Tasks/ApplyCompressionNegotiation.cs

@@ -16,7 +16,7 @@ public class ApplyCompressionNegotiation : Task
     [Required]
     public ITaskItem[] CandidateAssets { get; set; }
 
-    public bool AttachWeakETagToCompressedAssets { get; set; }
+    public string AttachWeakETagToCompressedAssets { get; set; }
 
     [Output]
     public ITaskItem[] UpdatedEndpoints { get; set; }
@@ -248,6 +248,27 @@ private StaticWebAssetEndpoint CreateUpdatedEndpoint(
             Quality = quality
         };
         Log.LogMessage(MessageImportance.Low, "  Created Content-Encoding selector for compressed asset '{0}' with size '{1}' is '{2}'", encodingSelector.Value, encodingSelector.Quality, relatedEndpointCandidate.Route);
+
+        // Handle EndpointProperty case for ETag
+        var endpointProperties = relatedEndpointCandidate.EndpointProperties.ToList();
+        if (string.Equals(AttachWeakETagToCompressedAssets, "EndpointProperty", StringComparison.Ordinal))
+        {
+            // Find ETag header in the related endpoint candidate
+            foreach (var header in relatedEndpointCandidate.ResponseHeaders)
+            {
+                if (string.Equals(header.Name, "ETag", StringComparison.Ordinal))
+                {
+                    Log.LogMessage(MessageImportance.Low, "  Adding original-resource endpoint property for related endpoint '{0}'", relatedEndpointCandidate.Route);
+                    endpointProperties.Add(new StaticWebAssetEndpointProperty
+                    {
+                        Name = "original-resource",
+                        Value = header.Value
+                    });
+                    break;
+                }
+            }
+        }
+
         var endpointCopy = new StaticWebAssetEndpoint
         {
             AssetFile = compressedAsset.Identity,
@@ -256,7 +277,7 @@ private StaticWebAssetEndpoint CreateUpdatedEndpoint(
                 ..relatedEndpointCandidate.Selectors,
                 encodingSelector
             ],
-            EndpointProperties = relatedEndpointCandidate.EndpointProperties
+            EndpointProperties = [.. endpointProperties]
         };
         var headers = new List<StaticWebAssetEndpointResponseHeader>(7);
         ApplyCompressedEndpointHeaders(headers, compressedEndpoint, relatedEndpointCandidate.Route);
@@ -373,7 +394,7 @@ private void ApplyRelatedEndpointCandidateHeaders(List<StaticWebAssetEndpointRes
                 Log.LogMessage(MessageImportance.Low, "  Adding header '{0}' to related endpoint '{1}'", header.Name, relatedEndpointCandidate.Route);
                 headers.Add(header);
             }
-            else if (AttachWeakETagToCompressedAssets && string.Equals(header.Name, "ETag", StringComparison.Ordinal))
+            else if (string.Equals(AttachWeakETagToCompressedAssets, "ResponseHeader", StringComparison.Ordinal) && string.Equals(header.Name, "ETag", StringComparison.Ordinal))
             {
                 // A resource can have multiple ETags. Since the uncompressed resource has an ETag,
                 // and we are serving the compressed resource from the same URL, we need to update