"""Base64 encoding in urlsafe format without padding.

Fixes Python base64 module's faults:
- Padding "==" is optional and not produced by base64url.enc
- Base64 type is str (stdlib uses bytes)
- Doesn't silently ignore invalid characters and produce garbage
"""

# We cannot use urlsafe_b64decode which misses the validation argument
from base64 import b64decode as _decode
from base64 import urlsafe_b64encode as _encode

__all__ = ["enc", "dec", "enc_lines", "dec_lines"]


def enc(data: bytes) -> str:
    """Base64 encode bytes to a URL-safe string without padding."""
    return _encode(data).decode("ascii").rstrip("=")


def dec(s: str, *, validate=True) -> bytes:
    """Decode standard or urlsafe Base64, with or without padding.

    Validation raises binascii.Error (ValueError) on invalid characters.
    If False, any unrecognized characters are silently ignored.
    """
    # Testing whether needs padding is slower, this is the fastest way and constant time.
    return _decode(s + -len(s) % 4 * "=", altchars=b"-_", validate=validate)


def enc_lines(data: bytes, length: int = 76, sep="\n") -> str:
    """Base64 encode bytes to a URL-safe string split into lines.

    Returns a string with newlines inserted after every `length` characters.
    The value should be a multiple of 4 for best compatibility with other systems.
    """
    s = enc(data)
    return sep.join([s[i : i + length] for i in range(0, len(s), length)])


def dec_lines(s: str) -> bytes:
    """Decode standard or urlsafe Base64 from a multiline string.

    All whitespace is ignored to allow formatted input.
    Raises binascii.Error (ValueError) on other invalid characters.
    """
    return dec("".join(s.split()))