import codecs
from custom_codecs.register import register_codec


def encode(text):
    result = []

    last_space = False

    for c in text:
        if c.isalnum():
            result.append(c)
            last_space = False
        elif c == " ":
            if not last_space:
                result.append(" ")
            last_space = True

    return "".join(result).encode("ascii")


def decode(data):
    return data.decode("ascii")


register_codec("alphanumeric", encode, decode)