feat: Support new Fingerprint and Integrity metadata required in .NET 9 SDK Preview 4

src/Uno.Wasm.Bootstrap/StaticWebAssetsResolverTask.cs

@@ -1,4 +1,5 @@
-// ******************************************************************
+
+// ******************************************************************
 // Copyright � 2015-2022 Uno Platform inc. All rights reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
@@ -22,6 +23,8 @@
 using System.Diagnostics;
 using System.IO;
 using System.Linq;
+using System.Numerics;
+using System.Security.Cryptography;
 using Microsoft.Build.Framework;
 using Microsoft.Build.Utilities;
 using Uno.Wasm.Bootstrap.Extensions;
@@ -70,20 +73,7 @@ public override bool Execute()
 			Log.LogMessage(MessageImportance.Low, $"Found {filteredAssets.Length} filtered assets");
 
 			StaticWebAsset =
-				filteredAssets.Select(asset =>
-					new TaskItem(asset, new Dictionary<string, string>
-					{
-						["SourceType"] = "Discovered",
-						["SourceId"] = AssemblyName,
-						["ContentRoot"] = fixedDistPath,
-						["RelativePath"] = asset.Replace(fixedDistPath, ""),
-						["BasePath"] = WebAppBasePath is { Length: > 0 } ? WebAppBasePath : "/",
-						["AssetKind"] = "All",
-						["AssetMode"] = "All",
-						["AssetRole"] = "Primary",
-						["OriginalItemSpec"] = asset,
-					}
-				))
+				filteredAssets.Select(asset => new TaskItem(asset, GetMetadata(asset, fixedDistPath)))
 				.ToArray();
 		}
 		else
@@ -93,4 +83,58 @@ public override bool Execute()
 
 		return true;
 	}
+
+	private Dictionary<string, string> GetMetadata(string asset, string fixedDistPath)
+	{
+		var dict = new Dictionary<string, string>
+		{
+			["SourceType"] = "Discovered",
+			["SourceId"] = AssemblyName,
+			["ContentRoot"] = fixedDistPath,
+			["RelativePath"] = asset.Replace(fixedDistPath, ""),
+			["BasePath"] = WebAppBasePath is { Length: > 0 } ? WebAppBasePath : "/",
+			["AssetKind"] = "All",
+			["AssetMode"] = "All",
+			["AssetRole"] = "Primary",
+			["OriginalItemSpec"] = asset,
+		};
+
+		var (fingerprint, integrity) = ComputeFingerprintAndIntegrity(asset, asset);
+		dict.Add("Fingerprint", fingerprint);
+		dict.Add("Integrity", integrity);
+		return dict;
+	}
+
+	// https://github.com/dotnet/sdk/blob/cc17704acfbee4b2ef49a82aa6f65aaa9cafffef/src/StaticWebAssetsSdk/Tasks/Data/StaticWebAsset.cs#L233-L248
+	private static (string fingerprint, string integrity) ComputeFingerprintAndIntegrity(string identity, string originalItemSpec)
+	{
+		using var file = File.Exists(identity) ?
+			File.OpenRead(identity) :
+			(File.Exists(originalItemSpec) ?
+				File.OpenRead(originalItemSpec) :
+				throw new InvalidOperationException($"No file exists for the asset at either location '{identity}' or '{originalItemSpec}'."));
+
+#if NET6_0_OR_GREATER
+        var hash = SHA256.HashData(file);
+#else
+		using var sha = SHA256.Create();
+		var hash = sha.ComputeHash(file);
+#endif
+		return (ToBase36(hash), Convert.ToBase64String(hash));
+	}
+
+	private static string ToBase36(byte[] hash)
+	{
+		const string chars = "0123456789abcdefghijklmnopqrstuvwxyz";
+
+		var result = new char[10];
+		var dividend = BigInteger.Abs(new BigInteger(hash.AsSpan().Slice(0, 9).ToArray()));
+		for (var i = 0; i < 10; i++)
+		{
+			dividend = BigInteger.DivRem(dividend, 36, out var remainder);
+			result[i] = chars[(int)remainder];
+		}
+
+		return new string(result);
+	}
 }