from itertools import cycle
from hashlib import md5
import os
from utils import listener


FLAG = b'crypto{??????????????????????????????????????}'


def bxor(a, b):
    return bytes(x ^ y for x, y in zip(a, b))


class Challenge():
    def __init__(self):
        self.before_input = "Enter data\n"

    def challenge(self, msg):
        if "option" not in msg:
            return {"error": "You must send an option to this server."}

        elif msg["option"] == "message":
            data = bytes.fromhex(msg["data"])

            if len(data) < len(FLAG):
              return {"error": "Bad input"}

            salted = bxor(data, cycle(FLAG))
            return {"hash": md5(salted).hexdigest()}

        else:
            return {"error": "Invalid option"}


"""
When you connect, the 'challenge' function will be called on your JSON
input.
"""
listener.start_server(port=13407)