Refactor code structure for improved readability and maintainability; optimize performance in key functions.

src/__Libraries/StellaOps.Evidence/Validation/EvidenceIndexValidator.cs

@@ -0,0 +1,63 @@
+using StellaOps.Evidence.Models;
+using StellaOps.Evidence.Serialization;
+
+namespace StellaOps.Evidence.Validation;
+
+public sealed class EvidenceIndexValidator : IEvidenceIndexValidator
+{
+    public ValidationResult Validate(EvidenceIndex index)
+    {
+        var errors = new List<ValidationError>();
+
+        if (index.Sboms.Length == 0)
+        {
+            errors.Add(new ValidationError("Sboms", "At least one SBOM required"));
+        }
+
+        foreach (var vex in index.VexDocuments)
+        {
+            if (vex.StatementCount == 0)
+            {
+                errors.Add(new ValidationError("VexDocuments", $"VEX {vex.VexId} has no statements"));
+            }
+        }
+
+        foreach (var proof in index.ReachabilityProofs)
+        {
+            if (proof.Status == ReachabilityStatus.Inconclusive &&
+                !index.Unknowns.Any(u => u.VulnerabilityId == proof.VulnerabilityId))
+            {
+                errors.Add(new ValidationError("ReachabilityProofs",
+                    $"Inconclusive reachability for {proof.VulnerabilityId} not recorded as unknown"));
+            }
+        }
+
+        foreach (var att in index.Attestations)
+        {
+            if (!att.SignatureValid)
+            {
+                errors.Add(new ValidationError("Attestations",
+                    $"Attestation {att.AttestationId} has invalid signature"));
+            }
+        }
+
+        if (index.IndexDigest is not null)
+        {
+            var computed = EvidenceIndexSerializer.ComputeDigest(index);
+            if (!string.Equals(computed, index.IndexDigest, StringComparison.OrdinalIgnoreCase))
+            {
+                errors.Add(new ValidationError("IndexDigest", "Digest mismatch"));
+            }
+        }
+
+        return new ValidationResult(errors.Count == 0, errors);
+    }
+}
+
+public interface IEvidenceIndexValidator
+{
+    ValidationResult Validate(EvidenceIndex index);
+}
+
+public sealed record ValidationResult(bool IsValid, IReadOnlyList<ValidationError> Errors);
+public sealed record ValidationError(string Field, string Message);

src/__Libraries/StellaOps.Evidence/Validation/SchemaLoader.cs

@@ -0,0 +1,27 @@
+using System.Reflection;
+
+namespace StellaOps.Evidence.Validation;
+
+internal static class SchemaLoader
+{
+    public static string LoadSchema(string fileName)
+    {
+        var assembly = Assembly.GetExecutingAssembly();
+        var resourceName = assembly.GetManifestResourceNames()
+            .FirstOrDefault(name => name.EndsWith(fileName, StringComparison.OrdinalIgnoreCase));
+
+        if (resourceName is null)
+        {
+            throw new InvalidOperationException($"Schema resource not found: {fileName}");
+        }
+
+        using var stream = assembly.GetManifestResourceStream(resourceName);
+        if (stream is null)
+        {
+            throw new InvalidOperationException($"Schema resource not available: {resourceName}");
+        }
+
+        using var reader = new StreamReader(stream);
+        return reader.ReadToEnd();
+    }
+}