"""模型文件：列举与安全解析。"""

from pathlib import Path

from config import MODELS_DIR

ALLOWED_SUFFIXES = {".glb", ".gltf"}
MEDIA_TYPES = {".glb": "model/gltf-binary", ".gltf": "model/gltf+json"}


def list_models() -> list[str]:
    if not MODELS_DIR.is_dir():
        return []
    names = [
        path.name
        for path in MODELS_DIR.iterdir()
        if path.is_file() and path.suffix.lower() in ALLOWED_SUFFIXES
    ]
    return sorted(names)


def resolve_model(name: str) -> Path | None:
    """只允许 models 目录下的直接子文件，防路径穿越。"""
    if not name or name != Path(name).name:
        return None
    candidate = (MODELS_DIR / name).resolve()
    if candidate.parent != MODELS_DIR.resolve():
        return None
    if candidate.is_file() and candidate.suffix.lower() in ALLOWED_SUFFIXES:
        return candidate
    return None


def media_type(path: Path) -> str:
    return MEDIA_TYPES.get(path.suffix.lower(), "application/octet-stream")