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

# Transposition Cipher Encrypt/Decrypt File
# https://www.nostarch.com/crackingcodes (BSD Licensed)

import time, os, sys, transpositionEncrypt, transpositionDecrypt


def main() -> None:
    inputFilename = "frankenstein.txt"
    # BE CAREFUL! If a file with the outputFilename name already exists,
    # this program will overwrite that file.
    outputFilename = "frankenstein.encrypted.txt"
    myKey = 10
    myMode = "encrypt"  # set to 'encrypt' or 'decrypt'
    # If the input file does not exist, then the program terminates early:
    if not os.path.exists(inputFilename):
        print("The file %s does not exist. Quitting..." % (inputFilename))
        sys.exit()
    # If the output file already exists, give the user a chance to quit:
    if os.path.exists(outputFilename):
        print(
            "This will overwrite the file %s. (C)ontinue or (Q)uit?" % (outputFilename)
        )
        response = input("> ")
        if not response.lower().startswith("c"):
            sys.exit()
    # Read in the message from the input file:
    fileObj = open(inputFilename)
    content = fileObj.read()
    fileObj.close()
    print("%sing..." % (myMode.title()))
    # Measure how long the encryption/decryption takes:
    startTime = time.time()
    if myMode == "encrypt":
        translated = transpositionEncrypt.encryptMessage(myKey, content)
    elif myMode == "decrypt":
        translated = transpositionDecrypt.decryptMessage(myKey, content)
    totalTime = round(time.time() - startTime, 2)
    print("%sion time: %s seconds" % (myMode.title(), totalTime))
    # Write out the translated message to the output file:
    outputFileObj = open(outputFilename, "w")
    outputFileObj.write(translated)
    outputFileObj.close()
    print("Done %sing %s (%s characters)." % (myMode, inputFilename, len(content)))
    print("%sed file is %s." % (myMode.title(), outputFilename))


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