feat(m9/T23a): folder sibling reorder (ReorderFolderAsync + command + handler)

src/ZB.MOM.WW.ScadaBridge.TemplateEngine/Services/TemplateFolderService.cs

@@ -2,6 +2,7 @@ using ZB.MOM.WW.ScadaBridge.Commons.Entities.Templates;
 using ZB.MOM.WW.ScadaBridge.Commons.Interfaces.Repositories;
 using ZB.MOM.WW.ScadaBridge.Commons.Interfaces.Services;
 using ZB.MOM.WW.ScadaBridge.Commons.Types;
+using ZB.MOM.WW.ScadaBridge.Commons.Types.Enums;
 
 namespace ZB.MOM.WW.ScadaBridge.TemplateEngine.Services;
 
@@ -152,6 +153,56 @@ public class TemplateFolderService
         return Result<TemplateFolder>.Success(folder);
     }
 
+    /// <summary>
+    /// Reorders a template folder relative to its siblings under the same parent by
+    /// swapping <see cref="TemplateFolder.SortOrder"/> with the adjacent sibling in the
+    /// requested direction. Siblings are ordered ascending by <see cref="TemplateFolder.SortOrder"/>
+    /// then <see cref="TemplateFolder.Name"/>; <see cref="ReorderDirection.Up"/> swaps with the
+    /// previous sibling and <see cref="ReorderDirection.Down"/> with the next. Reordering past
+    /// either end is a no-op (returns success without persisting or auditing).
+    /// </summary>
+    /// <param name="folderId">Id of the folder to reorder.</param>
+    /// <param name="direction">Direction to move the folder within its sibling set.</param>
+    /// <param name="user">Username of the actor performing the operation (for audit).</param>
+    /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task that resolves to the reordered <see cref="TemplateFolder"/>, or a failure result if the folder is not found.</returns>
+    public async Task<Result<TemplateFolder>> ReorderFolderAsync(
+        int folderId, ReorderDirection direction, string user,
+        CancellationToken cancellationToken = default)
+    {
+        var folder = await _repository.GetFolderByIdAsync(folderId, cancellationToken);
+        if (folder == null)
+            return Result<TemplateFolder>.Failure($"Folder with ID {folderId} not found.");
+
+        var all = await _repository.GetAllFoldersAsync(cancellationToken);
+
+        // Deterministic sibling ordering: ascending SortOrder, then Name as tie-breaker.
+        var siblings = all
+            .Where(f => f.ParentFolderId == folder.ParentFolderId)
+            .OrderBy(f => f.SortOrder)
+            .ThenBy(f => f.Name, StringComparer.OrdinalIgnoreCase)
+            .ToList();
+
+        var index = siblings.FindIndex(f => f.Id == folderId);
+        var adjacentIndex = direction == ReorderDirection.Up ? index - 1 : index + 1;
+
+        // At the end of the sibling set in the requested direction: no-op.
+        if (adjacentIndex < 0 || adjacentIndex >= siblings.Count)
+            return Result<TemplateFolder>.Success(folder);
+
+        var adjacent = siblings[adjacentIndex];
+
+        // Swap sort order with the adjacent sibling.
+        (folder.SortOrder, adjacent.SortOrder) = (adjacent.SortOrder, folder.SortOrder);
+
+        await _repository.UpdateFolderAsync(folder, cancellationToken);
+        await _repository.UpdateFolderAsync(adjacent, cancellationToken);
+        await _repository.SaveChangesAsync(cancellationToken);
+        await _auditService.LogAsync(user, "Reorder", "TemplateFolder", folder.Id.ToString(), folder.Name, folder, cancellationToken);
+
+        return Result<TemplateFolder>.Success(folder);
+    }
+
     /// <summary>
     /// Deletes an empty template folder. Fails if the folder contains sub-folders or templates.
     /// </summary>