"""Decimal utilities."""

from decimal import ROUND_HALF_UP, ROUND_UP, Decimal

# One billionth
DEFAULT_TOLERANCE = Decimal('1e-9')


def safe_round_up(
    value: Decimal | float | int | str,
    exp: Decimal | int = Decimal('1'),
    tolerance: Decimal = DEFAULT_TOLERANCE,
) -> Decimal:
    """Round up to the given decimal places, accounting for floating-point drift."""
    # Sanitize value
    if not isinstance(value, Decimal):
        value = Decimal(str(value))

    # Sanitize exp
    if isinstance(exp, int):
        exp = Decimal(10) ** -exp
    elif not isinstance(exp, Decimal):
        raise TypeError(f'exp must be int or Decimal, got {type(exp).__name__}')

    # Correct floating-point drift
    rounded = value.quantize(exp, rounding=ROUND_HALF_UP)
    value = rounded if abs(value - rounded) < tolerance else value

    return value.quantize(exp, rounding=ROUND_UP)


def to_cent(
    value: Decimal | float | int | str, tolerance: Decimal = DEFAULT_TOLERANCE
) -> Decimal:
    """Round up to the nearest cent, accounting for floating-point drift."""
    return safe_round_up(value, Decimal('0.01'), tolerance)