src/ingestion/file_detector.py

# src/ingestion/file_detector.py
from pathlib import Path
from typing import Optional


def detect_file_type(path: str) -> Optional[str]:
    """
    Returns one of: 'tcx', 'gpx', 'fit' or None if unknown.
    Accepts compressed (.gz) variants.
    """
    p = Path(path)
    name = p.name.lower()
    if name.endswith(".tcx") or name.endswith(".tcx.gz"):
        return "tcx"
    if name.endswith(".gpx") or name.endswith(".gpx.gz"):
        return "gpx"
    if name.endswith(".fit") or name.endswith(".fit.gz"):
        return "fit"
    return None