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

# Transposition File Hacker
# https://www.nostarch.com/crackingcodes (BSD Licensed)

import time, os, sys, transpositionDecrypt, detectEnglish
from typing import Optional


inputFilename = "frankenstein.encrypted.txt"
outputFilename = "frankenstein.decrypted.txt"


def main() -> None:
    if not os.path.exists(inputFilename):
        print("The file %s does not exist. Quitting." % (inputFilename))
        sys.exit()
    inputFile = open(inputFilename)
    content = inputFile.read()
    inputFile.close()
    hackedMessage = hackTransposition(content)
    if hackedMessage is not None:
        print("Writing decrypted text to %s." % (outputFilename))
        outputFile = open(outputFilename, "w")
        outputFile.write(hackedMessage)
        outputFile.close()
    else:
        print("Failed to hack encryption.")


# The hackTransposition() function's code was copy/pasted from
# transpositionHacker.py and had some modifications made.
def hackTransposition(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.)")
    for key in range(1, len(message)):
        print("Trying key #%s... " % (key), end="")
        sys.stdout.flush()
        # We want to track the amount of time it takes to test a single key,
        # so we record the time in startTime.
        startTime = time.time()
        decryptedText = transpositionDecrypt.decryptMessage(key, message)
        englishPercentage = round(detectEnglish.getEnglishCount(decryptedText) * 100, 2)
        totalTime = round(time.time() - startTime, 3)
        print("Test time: %s seconds, " % (totalTime), end="")
        sys.stdout.flush()  # Flush printed text to the screen.
        print("Percent English: %s%%" % (englishPercentage))
        if englishPercentage > 20:
            print()
            print("Key " + str(key) + ": " + decryptedText[:100])
            print()
            print("Enter D if done, anything else to continue hacking:")
            response = input("> ")
            if response.strip().upper().startswith("D"):
                return decryptedText
    return None


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