import string
import codecs
from custom_codecs.register import register_codec
from easybits import Bits

allowed_characters = string.ascii_letters + string.digits

def encode(text):
    """A (very) lossy encoder which only saves ASCII letters, numbers, and spaces.
    Everything else is discarded. All whitespace (e.g. tabs) is converted into spaces.
    """
    ascii_characters = []
    last_character_was_space = False
    for char in text:
        if char in allowed_characters:
            ascii_characters.append(char)
            last_character_was_space = False
        elif char in string.whitespace and not last_character_was_space:
            ascii_characters.append(' ')
            last_character_was_space = True
    ascii_text = ''.join(ascii_characters)
    return Bits(ascii_text).bytes

def decode(data):
    """A decoder which reads bytes and returns (string, length), 
    where length is the length of bytes consumed
    """
    text = ""
    for i, byte in enumerate(data):
        try:
            text += Bits(byte, length=8).ascii
        except OverflowError:
            print(i, byte)
            print(text + '|')
            print("Error")
            breakpoint()
    return text
    
register_codec(encode, decode, "alphanumeric")