Added mailboxes as local data sources (#1022)

app/MindWork AI Studio/Tools/Services/Indexing/IndexedDocumentIds.cs

@@ -0,0 +1,45 @@
+using System.Security.Cryptography;
+using System.Text;
+
+namespace AIStudio.Tools.Services.Indexing;
+
+/// <summary>
+/// The ids under which documents and their chunks are stored.
+/// </summary>
+/// <remarks>
+/// Derived rather than random, so the same document of the same data source always ends up under
+/// the same ids, in the vector store as well as in the index store. The formats must stay as they
+/// are: every stored id was made with them.
+/// </remarks>
+internal static class IndexedDocumentIds
+{
+    /// <summary>
+    /// The id of one chunk, which is also the id of its point in the vector store.
+    /// </summary>
+    /// <param name="dataSourceId">The data source the document belongs to.</param>
+    /// <param name="fingerprint">The fingerprint of the document as it was read.</param>
+    /// <param name="chunkIndex">The position of the chunk within the document.</param>
+    /// <returns>The chunk id.</returns>
+    public static string CreateChunkId(string dataSourceId, string fingerprint, int chunkIndex) =>
+        CreateStableGuid($"{dataSourceId}:chunk:{fingerprint}:{chunkIndex}");
+
+    /// <summary>
+    /// The id of a document's row in the index store, which its chunks point at.
+    /// </summary>
+    /// <param name="dataSourceId">The data source the document belongs to.</param>
+    /// <param name="absolutePath">What the row is stored under. For a file, its absolute path.</param>
+    /// <returns>The document id.</returns>
+    public static string CreateParentId(string dataSourceId, string absolutePath) =>
+        CreateStableGuid($"{dataSourceId}:parent-file:{absolutePath}");
+
+    private static string CreateStableGuid(string source)
+    {
+        var hash = SHA256.HashData(Encoding.UTF8.GetBytes(source));
+        var guidBytes = hash[..16].ToArray();
+
+        guidBytes[6] = (byte)((guidBytes[6] & 0x0F) | 0x40);
+        guidBytes[8] = (byte)((guidBytes[8] & 0x3F) | 0x80);
+
+        return new Guid(guidBytes).ToString();
+    }
+}