from __future__ import annotations

import os
from pathlib import Path


def weights_dir() -> Path:
    """Directory scanned for locally-bundled model weights.

    Defaults to ``models`` (relative to the working directory); override with the
    ``BGFILTER_WEIGHTS_DIR`` environment variable.
    """
    return Path(os.environ.get("BGFILTER_WEIGHTS_DIR", "models"))


def resolve_model_source(repo_id: str) -> str:
    """Map a HuggingFace repo id to a local weights folder when one is present.

    If ``<weights_dir>/<basename>`` exists it is returned (so models can be shipped
    as plain folders inside the project, e.g. ``ZhengPeng7/BiRefNet`` ->
    ``models/BiRefNet``); otherwise the repo id is returned unchanged so it loads
    from the HF hub/cache as before. An absolute/existing path is passed through.
    """
    if os.path.isdir(repo_id):
        return repo_id
    local = weights_dir() / repo_id.split("/")[-1]
    if local.is_dir():
        return str(local)
    return repo_id