Add BeatMods parsing and userdata restore

src/plugin_helper/userdata.py

@@ -84,6 +84,19 @@ def infer_windows_appdata_path(instance_path: Path) -> Path:
     return profile / "AppData" / "LocalLow" / "Hyperbolic Magnetism" / "Beat Saber"
 
 
+def infer_proton_appdata_path() -> Path:
+    return (
+        Path.home()
+        / ".local/share/BSManager/SharedContent/compatdata/pfx/drive_c/users/steamuser/AppData/LocalLow/Hyperbolic Magnetism/Beat Saber"
+    )
+
+
+def infer_appdata_path(instance_path: Path) -> Path:
+    if "Users" in instance_path.resolve().parts:
+        return infer_windows_appdata_path(instance_path)
+    return infer_proton_appdata_path()
+
+
 def sync_windows_data_repo(
     *,
     instance: str,
@@ -96,7 +109,7 @@ def sync_windows_data_repo(
         ("UserData", instance_path / "UserData", backup_root / "UserData"),
     ]
     if include_appdata:
-        appdata = appdata_path or infer_windows_appdata_path(instance_path)
+        appdata = appdata_path or infer_appdata_path(instance_path)
         sources.append(("AppData", appdata, backup_root / "AppData"))
 
     for label, source, _ in sources:
@@ -145,6 +158,63 @@ def sync_windows_data_repo(
     }
 
 
+def restore_windows_data_repo(
+    *,
+    instance: str,
+    instance_path: Path,
+    backup_root: Path,
+    appdata_path: Path | None = None,
+    include_appdata: bool = True,
+) -> dict[str, Any]:
+    descriptor_path = backup_root / "backup-descriptor.json"
+    if descriptor_path.is_file():
+        descriptor = json.loads(descriptor_path.read_text(encoding="utf-8"))
+        descriptor_instance = descriptor.get("instance")
+        if descriptor_instance and descriptor_instance != instance:
+            raise ValueError(
+                f"backup descriptor instance {descriptor_instance!r} does not match requested instance {instance!r}"
+            )
+
+    created_at = datetime.now(timezone.utc).strftime("%Y%m%dT%H%M%SZ")
+    restores: list[tuple[str, Path, Path]] = [
+        ("UserData", backup_root / "UserData", instance_path / "UserData"),
+    ]
+    if include_appdata:
+        appdata = appdata_path or infer_appdata_path(instance_path)
+        restores.append(("AppData", backup_root / "AppData", appdata))
+
+    for label, source, _ in restores:
+        if not source.is_dir():
+            raise FileNotFoundError(f"{label} backup not found: {source}")
+
+    restored: list[dict[str, Any]] = []
+    snapshots: list[dict[str, Any]] = []
+    for label, source, destination in restores:
+        snapshot: Path | None = None
+        if destination.exists():
+            snapshot = destination.parent / f"{destination.name}.pre-restore-{created_at}"
+            destination.rename(snapshot)
+            snapshots.append({"label": label, "path": str(snapshot)})
+
+        destination.parent.mkdir(parents=True, exist_ok=True)
+        shutil.copytree(source, destination, symlinks=True)
+        restored.append(
+            {
+                "label": label,
+                "source": str(source),
+                "destination": str(destination),
+                "fileCount": sum(1 for item in destination.rglob("*") if item.is_file()),
+                "snapshot": str(snapshot) if snapshot else None,
+            }
+        )
+
+    return {
+        "backupRoot": str(backup_root),
+        "restored": restored,
+        "snapshots": snapshots,
+    }
+
+
 def _ignore_backup_paths(source_root: Path, skipped: list[str]) -> Callable[[str, list[str]], set[str]]:
     def ignore(current_dir: str, names: list[str]) -> set[str]:
         ignored: set[str] = set()