from .math_big_integer import parse_big_integer
from .math_round_div import RoundingMode, round_div


def round_div_big(numerator: str, denominator: str, mode: RoundingMode) -> str:
    """math.round-div, for integers too big for a JavaScript number.

    Python's integers never overflow, so this is math.round-div itself; the
    capability exists so TypeScript and Rust, whose native integers stop at
    2^53 and 2^127, give the same answer from the same decimal strings.
    """
    n = parse_big_integer(numerator)
    d = parse_big_integer(denominator)
    if mode not in ("half-up", "half-even", "down", "up"):
        raise ValueError('unknown rounding mode "%s"' % (mode,))
    return str(round_div(n, d, mode))