"""金额与比率的定点运算。积分只向下取整，避免四舍五入把释放总额做超。"""

from __future__ import annotations

from decimal import Decimal, ROUND_DOWN

QUANT = Decimal("0.00000001")


def to_decimal(value: object) -> Decimal:
    if isinstance(value, Decimal):
        return value
    return Decimal(str(value))


def money(value: object) -> Decimal:
    return to_decimal(value).quantize(QUANT, rounding=ROUND_DOWN)


def rate(value: object) -> Decimal:
    number = to_decimal(value)
    if number < 0:
        number = Decimal("0")
    elif number > 1:
        number = Decimal("1")
    return number.quantize(QUANT, rounding=ROUND_DOWN)


def ratio(numerator: int, denominator: int) -> Decimal:
    if denominator <= 0:
        return Decimal("0")
    return rate(Decimal(numerator) / Decimal(denominator))