Support for post annotation label reassignement.

copienator/filesystem.py

@@ -92,3 +92,45 @@ def staged_files(
                 if not destination_path.exists():
                     saved.replace(destination_path)
             _remove_path(backup)
+
+
+def publish_file_sets(file_sets: dict[Path, tuple[Path, Iterable[str]]]) -> None:
+    """Commit several staged file sets together, rolling every set back on error.
+
+    Staging and destination directories must be on the same filesystem. Unlike
+    nesting staged_files, failure in a later directory restores earlier ones too.
+    """
+    token = uuid.uuid4().hex
+    backups: list[tuple[Path, Path]] = []
+    committed: list[Path] = []
+    try:
+        for target, (staging, remove) in file_sets.items():
+            target.mkdir(parents=True, exist_ok=True)
+            backup = target / f".publish-{token}.backup"
+            backup.mkdir()
+            backups.append((target, backup))
+            staged = sorted(path for path in staging.iterdir() if path.is_file())
+            names = {path.name for path in staged} | set(remove)
+            for name in sorted(names):
+                if Path(name).name != name:
+                    raise ValueError(f"Invalid output filename: {name}")
+                destination = target / name
+                if destination.exists() or destination.is_symlink():
+                    destination.replace(backup / name)
+            for source in staged:
+                destination = target / source.name
+                source.replace(destination)
+                committed.append(destination)
+    except Exception:
+        for destination in reversed(committed):
+            _remove_path(destination)
+        for target, backup in reversed(backups):
+            for saved in backup.iterdir():
+                saved.replace(target / saved.name)
+        raise
+    finally:
+        for _, backup in backups:
+            if backup.exists() and not any(backup.iterdir()):
+                backup.rmdir()
+    for _, backup in backups:
+        _remove_path(backup)