Asset Catalogs: write catalogs to disk when saving the blend file

The Asset Catalog Definition File is now saved whenever the blend file
is saved. The location of the CDF depends on where the blend file is
saved, and whether previously a CDF was already loaded, according to the
following rules. The first matching rule wins:

1. Already loaded a CDF from disk? -> Always write to that file.
2. The directory containing the blend file has a
   `blender_assets.cats.txt` file? -> Merge with & write to that file.
3. The directory containing the blend file is part of an asset library,
   as per the user's preferences? -> Merge with & write to
   `${ASSET_LIBRARY_ROOT}/blender_assets.cats.txt`
4. Create a new file `blender_assets.cats.txt` next to the blend file.

1 files changed, 62 insertions, 0 deletions

diff --git a/source/blender/blenkernel/intern/asset_catalog.cc b/source/blender/blenkernel/intern/asset_catalog.cc
index b65ae12e5a7..ee22e25a6ab 100644
--- a/source/blender/blenkernel/intern/asset_catalog.cc
+++ b/source/blender/blenkernel/intern/asset_catalog.cc
@@ -19,11 +19,14 @@
  */
 
 #include "BKE_asset_catalog.hh"
+#include "BKE_preferences.h"
 
 #include "BLI_fileops.h"
 #include "BLI_path_util.h"
 #include "BLI_string_ref.hh"
 
+#include "DNA_userdef_types.h"
+
 /* For S_ISREG() and S_ISDIR() on Windows. */
 #ifdef WIN32
 #  include "BLI_winstuff.h"
@@ -266,6 +269,65 @@ bool AssetCatalogService::write_to_disk(const CatalogFilePath &directory_for_new
   return catalog_definition_file_->write_to_disk();
 }
 
+bool AssetCatalogService::write_to_disk_on_blendfile_save(const char *blend_file_path)
+{
+  /* TODO(Sybren): deduplicate this and write_to_disk(...); maybe the latter function isn't even
+   * necessary any more. */
+
+  /* - Already loaded a CDF from disk? -> Always write to that file. */
+  if (this->catalog_definition_file_) {
+    merge_from_disk_before_writing();
+    return catalog_definition_file_->write_to_disk();
+  }
+
+  if (catalogs_.is_empty() && deleted_catalogs_.is_empty()) {
+    /* Avoid saving anything, when there is nothing to save. */
+    return true; /* Writing nothing when there is nothing to write is still a success. */
+  }
+
+  const CatalogFilePath cdf_path_to_write = find_suitable_cdf_path_for_writing(blend_file_path);
+  this->catalog_definition_file_ = construct_cdf_in_memory(cdf_path_to_write);
+  merge_from_disk_before_writing();
+  return catalog_definition_file_->write_to_disk();
+}
+
+CatalogFilePath AssetCatalogService::find_suitable_cdf_path_for_writing(
+    const CatalogFilePath &blend_file_path)
+{
+  /* Determine the default CDF path in the same directory of the blend file. */
+  char blend_dir_path[PATH_MAX];
+  BLI_split_dir_part(blend_file_path.c_str(), blend_dir_path, sizeof(blend_dir_path));
+  const CatalogFilePath cdf_path_next_to_blend = asset_definition_default_file_path_from_dir(
+      blend_dir_path);
+
+  if (BLI_exists(cdf_path_next_to_blend.c_str())) {
+    /* - The directory containing the blend file has a blender_assets.cats.txt file?
+     *    -> Merge with & write to that file. */
+    return cdf_path_next_to_blend;
+  }
+
+  const bUserAssetLibrary *asset_lib_pref = BKE_preferences_asset_library_containing_path(
+      &U, blend_file_path.c_str());
+  if (asset_lib_pref) {
+    /* - The directory containing the blend file is part of an asset library, as per
+     *   the user's preferences?
+     *    -> Merge with & write to ${ASSET_LIBRARY_ROOT}/blender_assets.cats.txt  */
+
+    char asset_lib_cdf_path[PATH_MAX];
+    BLI_path_join(asset_lib_cdf_path,
+                  sizeof(asset_lib_cdf_path),
+                  asset_lib_pref->path,
+                  DEFAULT_CATALOG_FILENAME.c_str(),
+                  NULL);
+
+    return asset_lib_cdf_path;
+  }
+
+  /* - Otherwise
+   *    -> Create a new file blender_assets.cats.txt next to the blend file. */
+  return cdf_path_next_to_blend;
+}
+
 std::unique_ptr<AssetCatalogDefinitionFile> AssetCatalogService::construct_cdf_in_memory(
     const CatalogFilePath &file_path)
 {