import decimal
from typing import (
    Callable,
    Tuple,
)

ABI_DECIMAL_PREC = 999

abi_decimal_context = decimal.Context(prec=ABI_DECIMAL_PREC)

ZERO = decimal.Decimal(0)
TEN = decimal.Decimal(10)


def ceil32(x: int) -> int:
    return x if x % 32 == 0 else x + 32 - (x % 32)


def compute_unsigned_integer_bounds(num_bits: int) -> Tuple[int, int]:
    return (
        0,
        2**num_bits - 1,
    )


def compute_signed_integer_bounds(num_bits: int) -> Tuple[int, int]:
    return (
        -1 * 2 ** (num_bits - 1),
        2 ** (num_bits - 1) - 1,
    )


def compute_unsigned_fixed_bounds(
    num_bits: int,
    frac_places: int,
) -> Tuple[decimal.Decimal, decimal.Decimal]:
    int_upper = compute_unsigned_integer_bounds(num_bits)[1]

    with decimal.localcontext(abi_decimal_context):
        upper = decimal.Decimal(int_upper) * TEN**-frac_places

    return ZERO, upper


def compute_signed_fixed_bounds(
    num_bits: int,
    frac_places: int,
) -> Tuple[decimal.Decimal, decimal.Decimal]:
    int_lower, int_upper = compute_signed_integer_bounds(num_bits)

    with decimal.localcontext(abi_decimal_context):
        exp = TEN**-frac_places
        lower = decimal.Decimal(int_lower) * exp
        upper = decimal.Decimal(int_upper) * exp

    return lower, upper


def scale_places(places: int) -> Callable[[decimal.Decimal], decimal.Decimal]:
    """
    Returns a function that shifts the decimal point of decimal values to the
    right by ``places`` places.
    """
    if not isinstance(places, int):
        raise ValueError(
            f"Argument `places` must be int.  Got value {places} "
            f"of type {type(places)}.",
        )

    with decimal.localcontext(abi_decimal_context):
        scaling_factor = TEN**-places

    def f(x: decimal.Decimal) -> decimal.Decimal:
        with decimal.localcontext(abi_decimal_context):
            return x * scaling_factor

    places_repr = f"Eneg{places}" if places > 0 else f"Epos{-places}"
    func_name = f"scale_by_{places_repr}"

    f.__name__ = func_name
    f.__qualname__ = func_name

    return f