"""Hooks to production tracking (Libreflow / Kitsu).

These functions are the single place where checks ask the outside world for
expected values. Return None when the information is unavailable: the
related checks are then skipped instead of failing.
"""


def get_shot_frame_range(ctx):
    """Return the expected (frame_start, frame_end) of the shot, or None.

    ``ctx`` is a ``core.CheckContext``: ``ctx.filepath``, ``ctx.filename_match``
    (groups "sequence" and "shot" of config.FILENAME_PATTERNS["LAYOUT"]) and
    ``ctx.scene`` help identify the shot.

    TODO: query Libreflow or Kitsu (gazu), e.g.::

        import gazu
        shot = gazu.shot.get_shot_by_name(sequence, shot_name)
        start = shot["data"]["frame_in"]; end = shot["data"]["frame_out"]
    """
    return None