__all__ = [
    'SNAKE_CASE_CHARACTERS',
    'is_snake_case',
    'str_to_snake_case',
]

import string

SNAKE_CASE_CHARACTERS = string.ascii_lowercase + string.digits + '_'


def is_snake_case(input_str: str) -> bool:
    """
    Returns True if the input string only consists of snake case characters (lowercase letters, digits, underscore).
    """
    return all(c in SNAKE_CASE_CHARACTERS for c in input_str)


def str_to_snake_case(input_str: str) -> str:
    """
    Converts any string to a snake case string: Whitespaces are replaced with an underscore, uppercase letters are
    converted to lowercase, and any non-alphanumeric character is removed.
    """
    # First, lowercase string and replace any consecutive whitespaces with a single underscore
    almost_snake_case = '_'.join(input_str.lower().split())

    # Now, remove all characters that are neither letters, digits, nor underscores
    return ''.join(filter(lambda c: c in SNAKE_CASE_CHARACTERS, almost_snake_case))