import mimetypes


def get_extension_from_content_type(content_type: str) -> str:
    """Return file extension (without dot) from a given content-type."""
    ext = mimetypes.guess_extension(content_type)
    if ext is None:
        # fallback for types mimetypes may miss
        mapping = {
            "image/webp": "webp",
            "image/jpeg": "jpg",
            "image/png": "png",
            "image/gif": "gif",
            "video/mp4": "mp4",
            "video/webm": "webm",
            "application/pdf": "pdf",
        }
        return mapping.get(content_type, "")
    return ext.lstrip(".")  # remove leading dot


def pick_team(uid: str, user_to_teams: dict, team_map: dict) -> str:
    """Return the best team ID for a user — preferring non-personal teams."""
    candidates = user_to_teams.get(uid, [])
    non_personal = [
        t for t in candidates
        if not team_map.get(t, {}).get("is_personal_team", False)
    ]
    return non_personal[0] if non_personal else (candidates[0] if candidates else "")