#!/usr/bin/env -S python3

import subprocess
import sys


def main():
    [_, input] = sys.argv
    input_tar = input + ".tar"
    output = input + ".cprmt"
    print("Compressing '" + input + "' into '" + output + "'.")
    subprocess.Popen(["tar", "cf", input_tar, input]).wait()
    input_tar_fd = open(input_tar, "rb")
    output_fd = open(output, "wb")
    byte_index = 0
    while True:
        read = input_tar_fd.read(1024)
        if len(read) == 0:
            break
        for byte in read:
            if byte_index == 0:
                output_fd.write(bytes([5, byte]))
            else:
                output_fd.write(bytes([byte]))
            byte_index += 1
            byte_index %= 4
    print("Done.")


if __name__ == "__main__": main()