import subprocess
import datetime
import re

import argparse

def write_result(filename, ping):
	with open(filename, "w") as f:
		f.write(f'Start time {datetime.datetime.now()}')
		for result in ping:
			f.write(result)
		f.write(f"End time {datetime.datetime.now()}")

def ping_subnet(subnet):
	for addr in range(1, 255):
		yield subprocess.Popen(["ping", f"{subnet}.{addr}", "-n", "1"], stdout=subprocess.PIPE) \
			.stdout.read()									\
			.decode()

def main(subnet, filename):
	write_result(filename, ping_subnet(subnet))

def parse_arguments():
	parser = argparse.ArgumentParser(usage=% (prog)s [options] <subnet>,
					description='ip checker',
					epilog="python ipscanner.py 192.168.1 -f somefile.txt")
	parser.add_argument('subnet', type=str, help='the subnet you want to ping')
	parser.add_argument('-f', '--filename', type=str, help='The filename')
	args = parser.parse_args()

	if not re.match(r"(\d{1,3}\.\d{1,3}\.\d{1,3})", args.subnet) \
		or any(a not in range(1, 255) for a in map(int, args.subnet.split("."))):
			parser.error("This is not a valid subnet... muhfukka.... doesn't that suck?")

	if " " in args.filename:
		parser.error("There cannot be whitespaces in the filename")

	return args.subnet, args.filename

if _name_ == '_main_':
	main(*parse_arguments())