#!/usr/bin/python3
# -*- coding: utf-8 -*-

# Affine Cipher Hacker
# https://www.nostarch.com/crackingcodes (BSD Licensed)

import affineCipher, detectEnglish, cryptomath
from typing import Optional

SILENT_MODE = False


def main() -> None:
    # You might want to copy & paste this text from the source code at
    # https://www.nostarch.com/crackingcodes/affineHacker.py
    myMessage = """"5QG9ol3La6QI93!xQxaia6faQL9QdaQG1!!axQARLa!!AuaRLQ\
ADQALQG93!xQxaGaAfaQ1QX3o1RQARL9Qda!AafARuQLX1LQALQI1iQX3o1RN"Q-5!1RQP36ARu"""

    hackedMessage = hackAffine(myMessage)

    if hackedMessage != None:
        # The plaintext is displayed on the screen. For the convenience of
        # the user, we copy the text of the code to the clipboard.
        print("Copying hacked message to clipboard:")
        print(hackedMessage)
    else:
        print("Failed to hack encryption.")


def hackAffine(message: str) -> Optional[str]:
    print("Hacking...")

    # Python programs can be stopped at any time by pressing Ctrl-C (on
    # Windows) or Ctrl-D (on Mac and Linux)
    print("(Press Ctrl-C or Ctrl-D to quit at any time.)")

    # Brute-force by looping through every possible key
    for key in range(len(affineCipher.SYMBOLS) ** 2):
        keyA = affineCipher.getKeyParts(key)[0]
        if cryptomath.gcd(keyA, len(affineCipher.SYMBOLS)) != 1:
            continue

        decryptedText = affineCipher.decryptMessage(key, message)
        if not SILENT_MODE:
            print("Tried Key %s... (%s)" % (key, decryptedText[:40]))

        if detectEnglish.isEnglish(decryptedText):
            # Check with the user if the decrypted key has been found.
            print()
            print("Possible encryption hack:")
            print("Key: %s" % (key))
            print("Decrypted message: " + decryptedText[:200])
            print()
            print("Enter D if done, anything else to continue hacking:")
            response = input("> ")

            if response.strip().upper().startswith("D"):
                return decryptedText
    return None


# If affineHacker.py is run (instead of imported as a module)
# call the main() function.
if __name__ == "__main__":
    main()