import os
import time
import datetime
import _socket
import traceback
import sys

NETWORK_CONNECTION_NAME = 'Ethernet' # change to your network connection name
RESTORE_DNS_SETTINGS_TO = 'dhcp' # set to 'dhcp' or 'static X.X.X.X' to restore dns settings after script work
LOGFILE_NAME = 'log.txt'

funcs = [
    'gethostbyaddr',
    'gethostbyname_ex'
]

dns_servers = (
    '8.8.4.4',
    '129.250.35.250',
    '156.154.70.22',
    '199.2.252.10',
    '204.194.232.200',
    '204.97.212.10',
    '208.67.220.220',
    '209.55.0.110',
    '209.55.1.220',
    '77.88.8.8',
    '77.88.8.88',
    '5.230.130.41',
    '87.118.126.225',
    '212.185.16.51',
    '51.255.48.247',
    '5.135.18.114',
    '74.63.222.26',
    '138.68.199.36',
    '201.158.6.14',
    '189.211.178.28',
    '46.101.26.141',
    '5.56.134.32',
    '195.110.58.92',
    '213.3.16.176',
    '62.167.1.132',
    '141.105.66.183',
    '77.34.36.138',
    '109.195.102.86',
    '84.237.20.90'
)

hostnames = (
    'ubuntu.com',
    'python.org',
    'google.com',
    'mysql.com',
    'microsoft.com',
    'yandex.ru',
    'lingvolive.com',
    'yahoo.com',
    'github.com',
)


def log_measures(duration_time, dns_server, hostname, func, error=''):
    with open(LOGFILE_NAME, 'a') as f:
        line = ';'.join(
            (
                datetime.datetime.now().strftime("%Y-%m-%d;%H:%M"),
                str(datetime.timedelta(seconds = duration_time)).ljust(14),
                dns_server.ljust(15),
                hostname.ljust(15),
                func,
                error,
            )
        )
        f.write(line + '\n')


def log_comment(text):
    with open(LOGFILE_NAME, 'a') as f:
        f.write('#{}: {}\n'.format(datetime.datetime.now().strftime("%Y-%m-%d;%H:%M"), text))


def main():
    log_comment('Test started')

    for func in funcs:
        func_work_time = 0

        for dns_server in dns_servers:
            os.system('netsh interface ip set dns "{}" static {}'. format(NETWORK_CONNECTION_NAME, dns_server))
            time.sleep(2) # waiting for the shell a bit
            os.system('ipconfig /flushdns')
            time.sleep(2) # waiting for the shell a bit
            for hostname in hostnames:
                try:
                    time1 = time.time()
                    getattr(_socket, func)(hostname)
                except:
                    time2 = time.time()
                    error = traceback.format_exception(*sys.exc_info())[-1].strip()
                    log_measures(time2-time1, dns_server, hostname, func, error)
                else:
                    time2 = time.time()
                func_work_time += time2 - time1

        log_comment('{} worked: {} sec'.format(func, func_work_time))

    # Restore settings
    os.system('netsh interface ip set dns "{}" {}'. format(NETWORK_CONNECTION_NAME, RESTORE_DNS_SETTINGS_TO))


if __name__ == '__main__':
    main()