from ics import Calendar

td_titles = ["TD"]
sh_titles = ["ANGLAIS", "Anglais", "ETHIQUE"]

def _filter_group(name: str, titles: list[str], group: str) -> bool | None:
    for title in titles:
        if title in name:
            return "Examen" in name or group == "all" or group in name

    return None

def _filter_event(name: str, td_group: str, sh_group: str) -> bool:
    res = _filter_group(name, sh_titles, sh_group)
    if res:
        return True

    elif res == None:
        if _filter_group(name, td_titles, td_group) != False:
            return True

    return False

def filter_calendar(calendar: Calendar, td_group: str, sh_group: str) -> Calendar:
    filtered_calendar = Calendar()

    for event in calendar.events:
        if _filter_event(event.name, td_group, sh_group):
            filtered_calendar.events.add(event)

    return filtered_calendar