from typing import List, Tuple

from utils import *


class WeakRNG:
    """Simple class for weak RNG"""

    def __init__(self) -> None:
        self.rstate = 0
        self.maxn = 255
        self.a = 0  # Set this to correct value
        self.b = 0  # Set this to correct value
        self.p = 257

    def init_state(self, rstate: int) -> None:
        """Initialise rstate"""
        self.rstate = rstate  # Set this to some value
        self.update_state()

    def update_state(self) -> None:
        """Update state"""
        self.rstate = (self.a * self.rstate + self.b) % self.p

    def get_prg_byte(self) -> int:
        """Return a new PRG byte and update PRG state"""
        b = self.rstate & 0xFF
        self.update_state()
        return b


def main() -> None:
    # Initialise weak rng
    wr = WeakRNG()
    wr.init_state(0)

    # Print ciphertext
    CH = "a432109f58ff6a0f2e6cb280526708baece6680acc1f5fcdb9523129434ae9f6ae9edc2f224b73a8"
    print("Full ciphertext in hexa:", CH)

    # Print known plaintext
    pknown = "Let all creation"
    nb = len(pknown)
    print("Known plaintext:", pknown)
    pkh = str_2_hex(pknown)
    print("Plaintext in hexa:", pkh)

    # Obtain first nb bytes of RNG
    gh = hexxor(pkh, CH[0 : nb * 2])
    print(gh)
    gbytes = []
    for i in range(nb):
        gbytes.append(ord(hex_2_str(gh[2 * i : 2 * i + 2])))
    print("Bytes of RNG: ")
    print(gbytes)

    # Break the LCG here:
    # TODO 1: Find a and b, and set them in the RNG

    # TODO 2: Predict/generate rest of RNG bytes

    # TODO 3: Decrypt plaintext

    # TODO 4: Print the full plaintext
    p = ...
    print("Full plaintext is:", p)


if __name__ == "__main__":
    main()