Asset Browser: Support dragging catalogs into top level

This was an oversight when I added catalog drag & drop support. I forgot
to add this for dragging catalogs into the top level by dragging into to
the "All" item as well. This made the drag & drop support rather broken
because it wouldn't work for a basic case.

2 files changed, 35 insertions, 6 deletions

diff --git a/source/blender/editors/asset/ED_asset_catalog.hh b/source/blender/editors/asset/ED_asset_catalog.hh
index 8da8fc0d6c9..cbfce16e9eb 100644
--- a/source/blender/editors/asset/ED_asset_catalog.hh
+++ b/source/blender/editors/asset/ED_asset_catalog.hh
@@ -20,6 +20,8 @@
 
 #pragma once
 
+#include <optional>
+
 #include "BKE_asset_catalog.hh"
 
 #include "BLI_string_ref.hh"
@@ -37,6 +39,18 @@ void ED_asset_catalog_remove(AssetLibrary *library, const blender::bke::CatalogI
 void ED_asset_catalog_rename(AssetLibrary *library,
                              blender::bke::CatalogID catalog_id,
                              blender::StringRefNull new_name);
-void ED_asset_catalog_move(AssetLibrary *library,
-                           blender::bke::CatalogID src_catalog_id,
-                           blender::bke::CatalogID dst_parent_catalog_id);
+/**
+ * Reinsert catalog identified by \a src_catalog_id as child to catalog identified by \a
+ * dst_parent_catalog_id. If \a dst_parent_catalog_id is not set, the catalog is moved to the root
+ * level of the tree.
+ * The name of the reinserted catalog is made unique within the parent. Note that moving a catalog
+ * to the same level it was before will also change its name, since the name uniqueness check isn't
+ * smart enough to ignore the item to be reinserted. So the caller is expected to handle this case
+ * to avoid unwanted renames.
+ *
+ * Nothing is done (debug builds run into an assert) if the given catalog IDs can't be identified.
+ */
+void ED_asset_catalog_move(
+    AssetLibrary *library,
+    blender::bke::CatalogID src_catalog_id,
+    std::optional<blender::bke::CatalogID> dst_parent_catalog_id = std::nullopt);
diff --git a/source/blender/editors/asset/intern/asset_catalog.cc b/source/blender/editors/asset/intern/asset_catalog.cc
index 8e1e5be2e47..218ebe48934 100644
--- a/source/blender/editors/asset/intern/asset_catalog.cc
+++ b/source/blender/editors/asset/intern/asset_catalog.cc
@@ -123,7 +123,7 @@ void ED_asset_catalog_rename(::AssetLibrary *library,
 
 void ED_asset_catalog_move(::AssetLibrary *library,
                            const CatalogID src_catalog_id,
-                           const CatalogID dst_parent_catalog_id)
+                           const std::optional<CatalogID> dst_parent_catalog_id)
 {
   bke::AssetCatalogService *catalog_service = BKE_asset_library_get_catalog_service(library);
   if (!catalog_service) {
@@ -132,9 +132,24 @@ void ED_asset_catalog_move(::AssetLibrary *library,
   }
 
   AssetCatalog *src_catalog = catalog_service->find_catalog(src_catalog_id);
-  AssetCatalog *dst_catalog = catalog_service->find_catalog(dst_parent_catalog_id);
+  if (!src_catalog) {
+    BLI_assert_unreachable();
+    return;
+  }
+  AssetCatalog *dst_catalog = dst_parent_catalog_id ?
+                                  catalog_service->find_catalog(*dst_parent_catalog_id) :
+                                  nullptr;
+  if (!dst_catalog && dst_parent_catalog_id) {
+    BLI_assert_unreachable();
+    return;
+  }
 
-  const AssetCatalogPath new_path = dst_catalog->path / StringRef(src_catalog->path.name());
+  std::string unique_name = catalog_name_ensure_unique(
+      *catalog_service, src_catalog->path.name(), dst_catalog ? dst_catalog->path.c_str() : "");
+  /* If a destination catalog was given, construct the path using that. Otherwise, the path is just
+   * the name of the catalog to be moved, which means it ends up at the root level. */
+  const AssetCatalogPath new_path = dst_catalog ? (dst_catalog->path / unique_name) :
+                                                  AssetCatalogPath{unique_name};
   const AssetCatalogPath clean_new_path = new_path.cleanup();
 
   if (new_path == src_catalog->path || clean_new_path == src_catalog->path) {