Rename Feedser to Concelier

src/StellaOps.Concelier.Exporter.Json/ExportDigestCalculator.cs

@@ -0,0 +1,52 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Security.Cryptography;
+using System.Text;
+
+namespace StellaOps.Concelier.Exporter.Json;
+
+public static class ExportDigestCalculator
+{
+    public static string ComputeTreeDigest(JsonExportResult result)
+    {
+        ArgumentNullException.ThrowIfNull(result);
+
+        using var sha256 = SHA256.Create();
+        var buffer = new byte[128 * 1024];
+
+        foreach (var file in result.FilePaths.OrderBy(static path => path, StringComparer.Ordinal))
+        {
+            var normalized = file.Replace("\\", "/");
+            var pathBytes = Encoding.UTF8.GetBytes(normalized);
+            _ = sha256.TransformBlock(pathBytes, 0, pathBytes.Length, null, 0);
+
+            var fullPath = ResolveFullPath(result.ExportDirectory, normalized);
+            using var stream = File.OpenRead(fullPath);
+            int read;
+            while ((read = stream.Read(buffer, 0, buffer.Length)) > 0)
+            {
+                _ = sha256.TransformBlock(buffer, 0, read, null, 0);
+            }
+        }
+
+        _ = sha256.TransformFinalBlock(Array.Empty<byte>(), 0, 0);
+        var hash = sha256.Hash ?? Array.Empty<byte>();
+        var hex = Convert.ToHexString(hash).ToLowerInvariant();
+        return $"sha256:{hex}";
+    }
+
+    private static string ResolveFullPath(string root, string normalizedRelativePath)
+    {
+        var segments = normalizedRelativePath.Split('/', StringSplitOptions.RemoveEmptyEntries);
+        var parts = new string[segments.Length + 1];
+        parts[0] = root;
+        for (var i = 0; i < segments.Length; i++)
+        {
+            parts[i + 1] = segments[i];
+        }
+
+        return Path.Combine(parts);
+    }
+}