feat: download missing assets for packaged installs

python/rcs/__init__.py

@@ -1,26 +1,87 @@
 """Robot control stack python bindings."""
 
+import io
 import os
+import zipfile
+from collections.abc import Callable
 from dataclasses import dataclass
+from pathlib import Path, PurePosixPath
 from typing import Any
 
 import numpy as np
+import requests
 from rcs._core import __version__, common
 
 from rcs import camera, envs, hand, sim
 
+GITHUB_ASSET_ARCHIVE_URL = "https://github.com/RobotControlStack/robot-control-stack/archive/refs/tags/{tag}.zip"
 
-def _rcs_prefix() -> str:
-    env_prefix = os.environ.get("RCS_PREFIX")
+
+def download_assets(
+    version: str,
+    prefix: Path,
+    github_asset_archive_url: str,
+    assets_dirname: str = "assets",
+) -> None:
+    tag = f"v{version.split('+', maxsplit=1)[0]}"
+    response = requests.get(github_asset_archive_url.format(tag=tag), timeout=60)
+    response.raise_for_status()
+
+    found_assets = False
+    with zipfile.ZipFile(io.BytesIO(response.content)) as archive:
+        for member in archive.infolist():
+            parts = PurePosixPath(member.filename).parts
+            if len(parts) < 2 or parts[1] != assets_dirname:
+                continue
+
+            found_assets = True
+            target = prefix.joinpath(*parts[1:])
+            if member.is_dir():
+                target.mkdir(parents=True, exist_ok=True)
+            else:
+                target.parent.mkdir(parents=True, exist_ok=True)
+                target.write_bytes(archive.read(member))
+
+    if not found_assets:
+        msg = f"Could not find {assets_dirname} in the downloaded GitHub archive."
+        raise FileNotFoundError(msg)
+
+
+def get_prefix(
+    env_prefix: str | None,
+    editable_prefix: Path,
+    default_prefix: Path,
+    version: str,
+    github_asset_archive_url: str,
+    assets_dirname: str = "assets",
+    download_fn: Callable[[str, Path, str, str], None] = download_assets,
+) -> str:
     if env_prefix:
-        return os.path.abspath(env_prefix)
-    return os.path.abspath(os.path.join(os.path.dirname(__file__), "../../"))
+        prefix = Path(env_prefix).expanduser().resolve()
+    else:
+        editable_prefix = editable_prefix.resolve()
+        if (editable_prefix / assets_dirname).is_dir():
+            return str(editable_prefix)
+        prefix = default_prefix.resolve()
+
+    assets_dir = prefix / assets_dirname
+    if not assets_dir.is_dir():
+        prefix.mkdir(parents=True, exist_ok=True)
+        print(f"Assets not found at {assets_dir}, downloading them now.")
+        download_fn(version, prefix, github_asset_archive_url, assets_dirname)
+
+    return str(prefix)
 
 
-RCS_PREFIX = _rcs_prefix()
+RCS_PREFIX = get_prefix(
+    os.environ.get("RCS_PREFIX"),
+    Path(__file__).resolve().parents[2],
+    Path.home() / ".rcs",
+    __version__,
+    GITHUB_ASSET_ARCHIVE_URL,
+)
 
 
-# TODO: assets must be "downloaded" first time this is imported
 @dataclass(kw_only=True)
 class RobotMetaConfig: