"""String helpers."""

import base64
import re


def sanitize_s3_path(string):
    """Strip invalid characters out of a string."""
    pattern = re.compile(r'[0-9a-zA-Z!\-_*\'()]')
    output = ''
    for char in string:
        if pattern.match(char):
            output = output + char
    return output


def from_camelcase_to_snakecase(name):
    """Convert camelCase strings to snake_case."""
    return re.sub('([a-z])([A-Z])', r'\1_\2', name).lower()


def base64decode(encoded_data):
    """Decode string, which was encoded with base64."""
    return base64.b64decode(encoded_data).decode()