#!/usr/bin/env nix-shell
#!nix-shell -i python3 -p "python3.withPackages (ppkgs: with ppkgs; [ pwntools ])"

from datetime import datetime, timedelta

from pwn import *

def gen_pin(prefix: str, i: int) -> str:
    return f"{prefix}{i}".ljust(8, '0')

def try_pin(pin: str) -> (int, bool):
    p = process("./pin_checker")

    p.recvuntil(b":\n")

    before = datetime.now()
    p.sendline(pin.encode())
    assert((line := p.recvline().strip()) == '8', f"{line}")
    assert((line := p.recvline().strip()) == 'Checking PIN...', f"{line}")
    result = p.recvline().decode()
    after = datetime.now()
    duration = after - before

    if result.strip() == 'Access denied.':
        return duration, False
    # NOTE: found by strings | grep "Access"
    elif result.startswith('Access granted'):
        return duration, True
    else:
        print("Unexpected result:")
        print(result)
        return duration, False

def main():
  current_prefix = ""
  for i in range(8):

      max_time = timedelta.min
      max_digit = None

      for d in range(10):
          pin = gen_pin(current_prefix, d)

          time, result = try_pin(pin)
          if max_time < time:
              max_time = time
              max_digit = d

          if result:
              print(f'FOUND PIN: {pin}')
              break
          else:
              print(f"{pin} -> {time}")

      current_prefix = current_prefix + str(max_digit)
      print(current_prefix)

if __name__ == '__main__':
  main()