Add support for Zstd compressed static files (#52)

Allow serving Zstd compressed files with the `.zst` extension.

The example has not been adjusted yet, because the SDK's supported CompressionFormats do not yet include zstd. However, static files compressed by other means (external tools) still work.

Rationale:

[Chrome 123 added zstd Content-Encoding support behind a feature flag `enable-zstd-content-encoding`](https://chromestatus.com/feature/6186023867908096), and [Mozilla has committed to implementing it in Firefox as well](mozilla/standards-positions#775).

Co-authored-by: Jeremy Kescher <jeremy.kescher@timetoact.at>

CompressedStaticFiles.AspNet/CompressedAlternativeFileProvider.cs

@@ -24,7 +24,8 @@ public class CompressedAlternativeFileProvider : IAlternativeFileProvider
         new Dictionary<string, string>()
         {
             { "gzip", ".gz" },
-            { "br", ".br" }
+            { "br", ".br" },
+            { "zstd", ".zst" }
         }.ToImmutableDictionary();
 
 
@@ -45,6 +46,7 @@ public void Initialize(FileExtensionContentTypeProvider fileExtensionContentType
     {
         // the StaticFileProvider would not serve the file if it does not know the content-type
         fileExtensionContentTypeProvider.Mappings[".br"] = "application/brotli";
+        fileExtensionContentTypeProvider.Mappings[".zst"] = "application/zstd";
     }
 
 

CompressedStaticFiles.AspNet/CompressedStaticFileMiddleware.cs

@@ -126,8 +126,7 @@ private void ProcessRequest(HttpContext context)
         //Find the smallest file from all our alternative file providers
         var smallestAlternativeFile = _alternativeFileProviders.Select(alternativeFileProvider => alternativeFileProvider.GetAlternative(context, fileSystem, originalFile))
                                                               .Where(af => af != null)
-                                                              .OrderBy(alternativeFile => alternativeFile?.Cost)
-                                                              .FirstOrDefault();
+                                                              .MinBy(alternativeFile => alternativeFile?.Cost);
 
         if (smallestAlternativeFile != null)
         {

CompressedStaticFiles.AspNet/CompressedStaticFiles.AspNet.csproj

@@ -9,7 +9,7 @@
 			Files need to be compressed and converted to other image formats before deploying.
 		</Description>
 		<PackageProjectUrl>https://github.com/material-blazor/CompressedStaticFiles.AspNetCore</PackageProjectUrl>
-		<PackageTags>aspnetcore;staticfiles;compression;precompressed;gzip;brotli;zopfli;webp;avif;</PackageTags>
+		<PackageTags>aspnetcore;staticfiles;compression;precompressed;gzip;brotli;zopfli;webp;avif;zstd</PackageTags>
 		<PackageReadmeFile>README.md</PackageReadmeFile>
 		<PackageReleaseNotes></PackageReleaseNotes>
 		<AssemblyVersion>1.0.0.0</AssemblyVersion>

README.md

@@ -41,8 +41,8 @@ This project allows you to serve precompressed files to the browser without havi
 ## Getting Started
 
 ### Precompress content
-Static nonimage files have to be precompressed using [Gzip](https://en.wikipedia.org/wiki/Gzip) and/or [Brotli](https://en.wikipedia.org/wiki/Brotli), see CompressedStaticFiles.Example.csproj for an automated methodology for producing compressed css & js files.
-The files must have the same filename as the source + `.br` or `.gzip` (`index.html` would be `index.html.br` for the Brotli version).
+Static nonimage files have to be precompressed using [Gzip](https://en.wikipedia.org/wiki/Gzip), [Brotli](https://en.wikipedia.org/wiki/Brotli) and/or [Zstd](https://en.wikipedia.org/wiki/Zstd), see CompressedStaticFiles.Example.csproj for an automated methodology for producing compressed css & js files.
+The files must have the same filename as the source + `.br`/`.gzip`/`.zstd` (`index.html` would be `index.html.br` for the Brotli version).
 
 ### Encode images
 Modern browsers support new image formats like webp and avif they can store more pixels per byte.
@@ -55,7 +55,7 @@ Replace `UseStaticFiles();` with `UseCompressedStaticFiles();` in `Startup.Confi
 By default CompressedStaticFiles is configured to allow slightly larger files for some image formats as they can store more pixels per byte, this can be disabled by calling `CompressedStaticFileOptions.RemoveImageSubstitutionCostRatio()`.
 
 ## Example
-An example can be found in the [Example](https://github.com/material-blazor/CompressedStaticFiles.AspNet/tree/main/CompressedStaticFiles.Example) directory.
+An example with Gzip and Brotli can be found in the [Example](https://github.com/material-blazor/CompressedStaticFiles.AspNet/tree/main/CompressedStaticFiles.Example) directory.
 By using this package the Lighthouse mobile performance went from `76` to `98` and the transferred size went from `526 kb` to `141 kb`.
 
 ## Acknowledgements
@@ -67,4 +67,4 @@ We built this cloned project because:
 
 - We wanted to update to the currently supported version of .NET;
 - To make some refinements that were to our taste; and
-- To add MSBuild code to the [example CSPROJ file](https://github.com/Material-Blazor/CompressedStaticFiles.AspNet/blob/main/CompressedStaticFiles.Example/CompressedStaticFiles.Example.csproj#L13) to build Brotli and Gzip compressed CSS and JS files.
+- To add MSBuild code to the [example CSPROJ file](https://github.com/Material-Blazor/CompressedStaticFiles.AspNet/blob/main/CompressedStaticFiles.Example/CompressedStaticFiles.Example.csproj#L13) to build Brotli, Gzip and Zstd compressed CSS and JS files.