Source code for ska_ser_skuid.base32

# https://www.crockford.com/base32.html
BASE32_ALPHABET = "0123456789abcdefghjkmnpqrstvwxyz"




def b32encode(n: int) -> str:
    """Encode a non-negative integer using Crockford Base32.

    Uses the alphabet ``0-9 a-z`` (excluding ``i``, ``l``, ``o``, ``u``).

    :param n: Non-negative integer to encode.
    :returns: Crockford Base32 string representation.
    :raises ValueError: If *n* is negative.
    """
    if n == 0:
        return "0"
    elif n < 0:
        raise ValueError(f"Only encodes positive integers, got {n}")
    encoded = ""
    while n > 0:
        n, remainder = divmod(n, 32)
        encoded = BASE32_ALPHABET[remainder] + encoded
    return encoded





def b32decode(encoded_id: str) -> int:
    """Decode a Crockford Base32 string back to an integer.

    :param encoded_id: A non-empty string using the Crockford Base32 alphabet.
    :returns: The decoded non-negative integer.
    :raises ValueError: If *encoded_id* is empty or contains an invalid character.
    """
    if not encoded_id:
        raise ValueError("Cannot decode empty string")
    decoded = 0
    for char in encoded_id:
        if char not in BASE32_ALPHABET:
            raise ValueError(f"Invalid base32 character: {char}")
        decoded = decoded * 32 + BASE32_ALPHABET.index(char)

    return decoded