feat: Implement Policy Engine Evaluation Service and Cache with unit tests

Temp commit to debug

src/Scanner/__Libraries/StellaOps.Scanner.Storage/ObjectStore/ArtifactObjectKeyBuilder.cs

@@ -0,0 +1,75 @@
+using System;
+using StellaOps.Scanner.Storage.Catalog;
+
+namespace StellaOps.Scanner.Storage.ObjectStore;
+
+/// <summary>
+/// Builds deterministic object keys for scanner artefacts stored in the backing object store.
+/// </summary>
+public static class ArtifactObjectKeyBuilder
+{
+    /// <summary>
+    /// Builds an object key for the provided artefact metadata.
+    /// </summary>
+    /// <param name="type">Artefact type.</param>
+    /// <param name="format">Artefact format.</param>
+    /// <param name="digest">Content digest (with or without algorithm prefix).</param>
+    /// <param name="rootPrefix">Optional root prefix to prepend (defaults to <c>scanner</c>).</param>
+    /// <returns>Deterministic storage key.</returns>
+    public static string Build(
+        ArtifactDocumentType type,
+        ArtifactDocumentFormat format,
+        string digest,
+        string? rootPrefix = null)
+    {
+        ArgumentException.ThrowIfNullOrWhiteSpace(digest);
+
+        var normalizedDigest = NormalizeDigest(digest);
+        var digestValue = ExtractDigest(normalizedDigest);
+
+        var prefix = type switch
+        {
+            ArtifactDocumentType.LayerBom => ScannerStorageDefaults.ObjectPrefixes.Layers,
+            ArtifactDocumentType.ImageBom => ScannerStorageDefaults.ObjectPrefixes.Images,
+            ArtifactDocumentType.Index => ScannerStorageDefaults.ObjectPrefixes.Indexes,
+            ArtifactDocumentType.Attestation => ScannerStorageDefaults.ObjectPrefixes.Attestations,
+            ArtifactDocumentType.Diff => "diffs",
+            _ => ScannerStorageDefaults.ObjectPrefixes.Images,
+        };
+
+        var extension = format switch
+        {
+            ArtifactDocumentFormat.CycloneDxJson => "sbom.cdx.json",
+            ArtifactDocumentFormat.CycloneDxProtobuf => "sbom.cdx.pb",
+            ArtifactDocumentFormat.SpdxJson => "sbom.spdx.json",
+            ArtifactDocumentFormat.BomIndex => "bom-index.bin",
+            ArtifactDocumentFormat.DsseJson => "artifact.dsse.json",
+            _ => "artifact.bin",
+        };
+
+        var key = $"{prefix}/{digestValue}/{extension}";
+
+        if (string.IsNullOrWhiteSpace(rootPrefix))
+        {
+            return key;
+        }
+
+        return $"{TrimTrailingSlash(rootPrefix)}/{key}";
+    }
+
+    private static string NormalizeDigest(string digest)
+        => digest.Contains(':', StringComparison.Ordinal)
+            ? digest.Trim()
+            : $"sha256:{digest.Trim()}";
+
+    private static string ExtractDigest(string normalizedDigest)
+    {
+        var parts = normalizedDigest.Split(':', 2, StringSplitOptions.TrimEntries);
+        return parts.Length == 2 ? parts[1] : normalizedDigest;
+    }
+
+    private static string TrimTrailingSlash(string value)
+        => string.IsNullOrWhiteSpace(value)
+            ? string.Empty
+            : value.Trim().TrimEnd('/');
+}

src/Scanner/__Libraries/StellaOps.Scanner.Storage/Services/ArtifactStorageService.cs

@@ -50,8 +50,12 @@ public sealed class ArtifactStorageService
         try
         {
             var normalizedDigest = $"sha256:{digestHex}";
-            var artifactId = CatalogIdFactory.CreateArtifactId(type, normalizedDigest);
-            var key = BuildObjectKey(type, format, normalizedDigest);
+        var artifactId = CatalogIdFactory.CreateArtifactId(type, normalizedDigest);
+        var key = ArtifactObjectKeyBuilder.Build(
+            type,
+            format,
+            normalizedDigest,
+            _options.ObjectStore.RootPrefix);
             var descriptor = new ArtifactObjectDescriptor(
                 _options.ObjectStore.BucketName,
                 key,
@@ -137,45 +141,4 @@ public sealed class ArtifactStorageService
         return (bufferStream, total, digestHex);
     }
 
-    private string BuildObjectKey(ArtifactDocumentType type, ArtifactDocumentFormat format, string digest)
-    {
-        var normalizedDigest = digest.Split(':', 2, StringSplitOptions.TrimEntries)[^1];
-        var prefix = type switch
-        {
-            ArtifactDocumentType.LayerBom => ScannerStorageDefaults.ObjectPrefixes.Layers,
-            ArtifactDocumentType.ImageBom => ScannerStorageDefaults.ObjectPrefixes.Images,
-            ArtifactDocumentType.Diff => "diffs",
-            ArtifactDocumentType.Index => ScannerStorageDefaults.ObjectPrefixes.Indexes,
-            ArtifactDocumentType.Attestation => ScannerStorageDefaults.ObjectPrefixes.Attestations,
-            _ => ScannerStorageDefaults.ObjectPrefixes.Images,
-        };
-
-        var extension = format switch
-        {
-            ArtifactDocumentFormat.CycloneDxJson => "sbom.cdx.json",
-            ArtifactDocumentFormat.CycloneDxProtobuf => "sbom.cdx.pb",
-            ArtifactDocumentFormat.SpdxJson => "sbom.spdx.json",
-            ArtifactDocumentFormat.BomIndex => "bom-index.bin",
-            ArtifactDocumentFormat.DsseJson => "artifact.dsse.json",
-            _ => "artifact.bin",
-        };
-
-        var rootPrefix = _options.ObjectStore.RootPrefix;
-        if (string.IsNullOrWhiteSpace(rootPrefix))
-        {
-            return $"{prefix}/{normalizedDigest}/{extension}";
-        }
-
-        return $"{TrimTrailingSlash(rootPrefix)}/{prefix}/{normalizedDigest}/{extension}";
-    }
-
-    private static string TrimTrailingSlash(string prefix)
-    {
-        if (string.IsNullOrWhiteSpace(prefix))
-        {
-            return string.Empty;
-        }
-
-        return prefix.TrimEnd('/');
-    }
-}
+}