#!/usr/bin/env python
from pathlib import Path
from argparse import ArgumentParser
from io import BytesIO

from Crypto.Cipher import AES

import config as cfg


if __name__ == '__main__':
    parser = ArgumentParser(description='encrypt or decrypt files')
    parser.add_argument('infile', type=str, help='input file')
    parser.add_argument('outfile', type=str, help='output file')
    pgroup = parser.add_mutually_exclusive_group(required=True)
    pgroup.add_argument('--encrypt', '-e', action='store_true',
                        help='encrypt file')
    pgroup.add_argument('--decrypt', '-d', action='store_true',
                        help='decrypt file')
    args = parser.parse_args()

    args.infile = Path(args.infile)
    args.outfile = Path(args.outfile)

    # for a real application, use a better nonce
    cipher = AES.new(
        cfg.CRYPT_KEY.encode(), AES.MODE_EAX,
        nonce=cfg.CRYPT_KEY.encode()  # @todo  HERE BE DRAGONS!
    )
    
    cryptfunc = None    
    if args.encrypt:
        cryptfunc = cipher.encrypt
    else:
        cryptfunc = cipher.decrypt
        
    args.outfile.write_bytes(
        cryptfunc(
            args.infile.read_bytes()
        )
    )