#!/usr/bin/env python

import hashlib
import time
import subprocess
import sys


def get_file_hash(filename):
    hasher = hashlib.sha256()
    with open(filename, 'rb') as f:
        hasher.update(f.read())
    return hasher.hexdigest()


def main(script_name, interval=1):
    last_hash = None
    process = None

    while True:
        try:
            current_hash = get_file_hash(script_name)
            if current_hash != last_hash:
                last_hash = current_hash
                if process and process.poll() is None:
                    process.terminate()
                print(f"Detected change in {script_name}, running script...")
                process = subprocess.Popen(['pypy3', script_name], shell=False)
            time.sleep(interval)
        except KeyboardInterrupt:
            if process:
                process.terminate()
            break
        except FileNotFoundError:
            print("The file was not found. Make sure the script name is correct.")
            break

if __name__ == "__main__":
    main(sys.argv[1])