import re
import smtplib
import logging
import socket
import dns.resolver
from datetime import datetime
import multiprocessing


MX_DNS_CACHE = {}
MX_CHECK_CACHE = {}
smtp = smtplib.SMTP(timeout=0.4)


def get_mx_ip(hostname):
    if hostname not in MX_DNS_CACHE:
        try:
            MX_DNS_CACHE[hostname] = dns.resolver.query(hostname, 'MX')
        except (dns.resolver.NXDOMAIN, dns.resolver.NoAnswer):
            MX_DNS_CACHE[hostname] = None

    return MX_DNS_CACHE[hostname]



def validate_email(email, check_mx=False, verify=False, debug=False, smtp_timeout=10):
    """This will check valid email syntax by django validators and check hostname and local name
    by using the updated library dns.resolver and verify the email by smtp library.
    Caching the result in MX_DNS_CACHE to iprove performance.
    """
    try:
        check_mx |= verify
        if check_mx:
            hostname = email[email.find('@') + 1:]
            # try:
            #     mx_hosts = dns.resolver.query(hostname, 'MX')
            # except (dns.resolver.NXDOMAIN, dns.resolver.NoAnswer):
            #     return False
            # mx_hosts = get_mx_ip(hostname)
            if hostname in MX_DNS_CACHE:
                mx_hosts = MX_DNS_CACHE[hostname]
            else:
                mx_hosts = get_mx_ip(hostname)
            if mx_hosts is None:
                return False
            for mx in mx_hosts:
                try:
                    if not verify and mx in MX_CHECK_CACHE:
                        return MX_CHECK_CACHE[mx]

                    smtp.connect(mx.exchange.to_text())
                    # b = datetime.now() - a
                    # print "After connecting... ", b
                    MX_CHECK_CACHE[mx] = True
                    if not verify:
                        try:
                            smtp.quit()
                        except smtplib.SMTPServerDisconnected:
                            pass
                        return True
                    # a = datetime.now()
                    status, _ = smtp.helo()
                    # b = datetime.now() -a
                    # print "after sending email...", b
                    if status != 250:
                        smtp.quit()
                        if debug:
                            logger.debug(u'%s answer: %s - %s', mx, status, _)
                        continue
                    smtp.mail('')
                    status, _ = smtp.rcpt(email)
                    if status == 250:
                        smtp.quit()
                        return True
                    if debug:
                        logger.debug(u'%s answer: %s - %s', mx, status, _)
                    smtp.quit()
                except smtplib.SMTPServerDisconnected:  # Server not permits verify user
                    if debug:
                        logger.debug(u'%s disconected.', mx)
                except smtplib.SMTPConnectError:
                    if debug:
                        logger.debug(u'Unable to connect to %s.', mx)
            return None
    except AssertionError:
        return False
    except (socket.error) as e:
        if debug:
            logger.debug('ServerError or socket.error exception raised (%s).', e)
        return None
    return True


if __name__ == '__main__':

    emails = [] # add emails

    b = datetime.now()


    def validate(email):
        a = datetime.now()
        value = validate_email(email, verify=True)
        delta = datetime.now() - a
        print value, email, (delta.microseconds + delta.microseconds/1E6)

    def lookup(email):
        hostname = email[email.find('@') + 1:]
        max_hosts = get_mx_ip(hostname)
        return max_hosts

    pool = multiprocessing.Pool()
    result = pool.map(lookup, emails)
    finalresult = pool.map(validate, emails)
    delta = datetime.now() - b
    print delta.seconds + delta.microseconds/1E6