from .math_round_div import round_div
from .retail_volumetric_weight_types import ChargeableWeight


def _whole(value: object) -> bool:
    return isinstance(value, int) and not isinstance(value, bool)


def chargeable_weight(
    length_mm: int,
    width_mm: int,
    height_mm: int,
    actual_grams: int,
    divisor: int,
    round_up_to_grams: int,
) -> ChargeableWeight:
    """The weight a carrier charges on: the greater of actual and volumetric,
    rounded up to the carrier's billing step.

    mm³ / (cm³ per kg) is exactly grams, so everything stays in integers.
    """
    for d in (length_mm, width_mm, height_mm):
        if not _whole(d) or d < 1:
            raise ValueError("dimensions must be 1 mm or more, received %r" % (d,))
    if not _whole(actual_grams) or actual_grams < 0:
        raise ValueError("actualGrams must not be negative, received %r" % (actual_grams,))
    if not _whole(divisor) or divisor < 1:
        raise ValueError("divisor must be 1 or more, received %r" % (divisor,))
    if not _whole(round_up_to_grams) or round_up_to_grams < 1:
        raise ValueError("roundUpToGrams must be 1 or more, received %r" % (round_up_to_grams,))
    volumetric_grams = round_div(length_mm * width_mm * height_mm, divisor, "up")
    heavier = max(actual_grams, volumetric_grams)
    return ChargeableWeight(
        actual_grams=actual_grams,
        volumetric_grams=volumetric_grams,
        chargeable_grams=round_div(heavier, round_up_to_grams, "up") * round_up_to_grams,
        basis="volumetric" if volumetric_grams > actual_grams else "actual",
    )