utilities.py

"""Utilities."""

import sys
from typing import Dict, Optional

RGB_RANGE = 0b11111111


def bit_mask(size: int) -> int:
    """Return a bit mask with `size` number of 1-s."""
    if size < 0:
        raise ValueError('{0:d} B TOO SMALL BB'.format(size))
    elif size == 0:
        return 0
    else:
        return int('1' * size, base=2)


def query_user(question: str, default: Optional[bool]=None) -> bool:
    """Ask the user a yes/no question and return the response.

    Seeded from from
    https://stackoverflow.com/questions/3041986/apt-command-line-interface-like-yes-no-input

    Args:
        question: A prompt to provide to the user.
        default: An optional presumed answer, if the user just hits <Enter>.
            It must be "yes" (the default), "no" or None (meaning
            an answer is required of the user).

    Returns:
        True if the user specifies a truthy variant, False if the user specifies
        a falsy variant, or the default value.
    """
    if default is None:
        prompt = '[y/n]'
    elif default is True:
        prompt = '[Y/n]'
    elif default is False:
        prompt = '[y/N]'
    else:
        raise ValueError(f'invalid default answer: "{default}"')

    response_to_bool: Dict[str, bool] = {
        'yes': True,
        'y': True,
        'no': False,
        'n': False
    }
    while True:
        sys.stdout.write(f'{question} {prompt}: ')
        choice = input().lower()
        if default is not None and not choice:
            return default
        elif choice in response_to_bool:
            return response_to_bool[choice]
        else:
            print(
                'Please respond with one of "{0:s}"'.format(
                    '", "'.join(response_to_bool.keys())))