WaitForFlatFieldFiberPos

class WaitForFlatFieldFiberPos(KPFFunction):
    '''Wait for the flat field fiber aperture via the `kpfcal.FF_FIBERPOS`
    keyword.

    Args:
        FF_FiberPos (str): The name of the flat field fiber position desired.
            Allowed Values: "Blank", "6 mm f/5", "7.5 mm f/4", "10 mm f/3",
            "13.2 mm f/2.3", "Open".
        wait (bool): Wait for move to complete before returning? default: True

    KTL Keywords Used

    - `kpfcal.FF_FIBERPOS`
    '''
    @classmethod
    def pre_condition(cls, args):
        keyword = ktl.cache('kpfcal', 'FF_FiberPos')
        allowed_values = list(keyword._getEnumerators())
        if 'Unknown' in allowed_values:
            allowed_values.pop(allowed_values.index('Unknown'))
        check_input(args, 'FF_FiberPos', allowed_values=allowed_values)

    @classmethod
    def perform(cls, args):
        target = args.get('FF_FiberPos')
        timeout = cfg.getfloat('times', 'nd_move_time', fallback=20)
        expr = f"($kpfcal.FF_FiberPos == '{target}')"
        success = ktl.waitFor(expr, timeout=timeout)
        if success is False:
            log.error(f"Timed out waiting for FF_FiberPos filter wheel")

    @classmethod
    def post_condition(cls, args):
        target = args.get('FF_FiberPos')
        expr = f"($kpfcal.FF_FiberPos == '{target}')"
        success = ktl.waitFor(expr, timeout=0.1)

    @classmethod
    def add_cmdline_args(cls, parser):
        parser.add_argument('FF_FiberPos', type=str,
                            choices=["Blank", "6 mm f/5", "7.5 mm f/4",
                                     "10 mm f/3", "13.2 mm f/2.3", "Open"],
                            help='Wide flat aperture to use.')
        return super().add_cmdline_args(parser)