#!/usr/bin/python3


import smtplib, imaplib
import random
import logging
from datetime import datetime
import os, time, shutil
import re
import subprocess

def days_between(d1, d2):
    return abs((d2 - d1).days)

def need_to_rotate_log(logfile):
    # the log file contains the date per line, so get first line of log, it is
    # when the log started
    try:
        file_obj = open(logfile, 'r')
    except:
        return 0
    Lines = file_obj.readlines()
    first_line = Lines[0]
    file_obj.close()

    # get just the data to convert
    m = re.search('(\d+:\d+:\d+ \d+-\d+-\d+) .*', first_line)
    start_of_file = datetime. strptime(m.group(1), '%H:%M:%S %d-%m-%y')
    now = datetime.now()
    log_file_age_days = days_between(now, start_of_file )
    return log_file_age_days > 7

# function that sends a message using smtp to port 467
def SendMessage( server, username, password, nonce, f ):
    msg='To: {} \r\nFrom: {}\r\nSubject: Test from python\r\nDate: \r\nTEST {}'.format( username, username, str(nonce))

    # connect to mail server
    try:
        logging.info( "about to smtp_sll" );
        s = smtplib.SMTP_SSL(host=server)
        conn_time = time.time_ns();
        logging.info( "about to login" );
        s.login(username,password)
        login_time = time.time_ns();
        logging.info( "about to send" );
        s.sendmail( username, username, msg)
        send_time = time.time_ns();
        logging.info( "sent" );
    except smtplib.SMTPConnectError as e:
        logging.error( "Failed to connect to {} ({})".format(server, e.strerror))
        print('node_mail_synth_trans{what="mail_working"} 0', file=f )
    except smtplib.SMTPAuthenticationError as e:
        logging.error( "Failed to autheticate to {} with user: {} ({})".format(server, username, e.strerror))
        print('node_mail_synth_trans{what="mail_working"} 0', file=f )
    except smtplib.SMTPRecipientsRefused as e:
        logging.error( "Recipient failed {} : ({})".format(username, e.strerror))
        print('node_mail_synth_trans{what="mail_working"} 0', file=f )
    except smtplib.SMTPException as e:
        logging.error( "Generic SMTP exception, not one I cared about ({})".format(e.strerror))
        print('node_mail_synth_trans{what="mail_working"} 0', file=f )
    finally:
        if s:
            s.quit()
            quit_time = time.time_ns();
            logging.info("Successfully sent email: %d" % nonce )
            smtp_elapsed=(quit_time-start_time)/1000000
            logging.info("Time to send (ms): "+ str(smtp_elapsed))
            print('node_mail_synth_trans{what="smtp_time_in_ms"} %d' % smtp_elapsed, file=f)
            print('node_mail_synth_trans{what="smtp_working"} 1', file=f )

# function that searches for message just sent in imap, and deletes it
def ReceiveMessage( server, username, password, nonce, start_time, f ):
    try:
        imap_start_time = time.time_ns();
        conn = imaplib.IMAP4_SSL(server)
        imap_conn_time = time.time_ns();
    except imaplib.IMAP4.error as e:
        logging.error( "IMAP: Failed to connect ({})".format(e.strerror))
        print('node_mail_synth_trans{what="mail_working"} 0', file=f )

    try:
        conn.login(username,password)
        imap_login_time = time.time_ns();
    except imaplib.IMAP4.error as e:
        logging.error( "IMAP: failed to login ({})".format(e.strerror))
        print('node_mail_synth_trans{what="mail_working"} 0', file=f )

    try:
        conn.select('Inbox')
        search_str="TEST " + str(nonce)
        typ, data = conn.search(None,'(BODY "' + search_str + '")' )
        imap_search_time = time.time_ns();

        if data[0] == b'':
            raise Exception("search returned no data")
        for num in data[0].split():
            typ, data = conn.fetch(num,'(RFC822)')
            conn.store(num, '+FLAGS', '\\Deleted')
            imap_retr_time = time.time_ns();
        conn.expunge()
        imap_del_time = time.time_ns();
    except imaplib.IMAP4.error as e:
        logging.error( "IMAP: Could not find email {}".format(e.strerror))    
        print('node_mail_synth_trans{what="mail_working"} 0', file=f )
    finally:
        if conn:
            conn.close()
            imap_close_time = time.time_ns();
            # adding a 1 second sleep because my logs say it is deleting emails, but the emails are still in my folder, and also deleting ANY TEST emails, so if a subsequent run
            # works, it gets rid of the old ones that did fail for some reason
            time.sleep(1)
            conn.select('Inbox')
            search_str="TEST "
            typ, data = conn.search(None,'(BODY "' + search_str + '")' )
            # if there is still data, something didn't delete as expected, so
            # just clean it up
            if data[0] != b'':
                for num in data[0].split():
                    typ, data = conn.fetch(num,'(RFC822)')
                    conn.store(num, '+FLAGS', '\\Deleted')
                conn.expunge()
            conn.logout()
            imap_elapsed=(imap_close_time-imap_start_time)/1000000
            total_elapsed=(imap_close_time-start_time)/1000000 - 5000
            logging.info("time to recv email: %d" % imap_elapsed )
            logging.info("Successfully found and deleted email: %d" % nonce)
            print('node_mail_synth_trans{what="imap_time_in_ms"} %d' % imap_elapsed, file=f)
            print('node_mail_synth_trans{what="total_time_in_ms"} %d' % total_elapsed, file=f)
            print('node_mail_synth_trans{what="imap_working"} 1', file=f )
            print('node_mail_synth_trans{what="mail_working"} 1', file=f )

def Fail2BanCount():
    try:
        o = subprocess.run(["sudo", "/bin/docker", "exec", "mail", "fail2ban"], stdout=subprocess.PIPE, text=True )
        logging.info( f"Fail2ban returned: '{str(o.stdout.strip())}' ")
        out=str(o.stdout.strip()).split('\n')[1]
        ip_addresses = re.findall(r'\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}', out)
        unique_ip_count = len(set(ip_addresses))
        print( 'node_mail_synth_trans{what="fail2ban_cnt"} ' + str(unique_ip_count), file=f )
    except Exception as e:
        logging.error( f"Fail2ban: failed to get output for fail2ban ({e})" )
        print('node_mail_synth_trans{what="fail2ban_cnt"} 0', file=f )

# login using travel as its never really used (if I do anything dumb, it should
# have no real impact on mail that matters)
server='mail.depaoli.id.au'
username='travel@depaoli.id.au'
password='%fId0bPIE0Y2JZTzODJ%#p9V'

# set up unique message to send
nonce = random.randint(1,99999999)

# open file for writing prometheus formatted data into
f = open('/srv/docker/container/node-exporter/textfile_collector/mail.prom', 'w')

# put required help/type text in
print('# HELP node_mail_synth_trans details of last synthetic mail transaction (full send/recv of an email)', file=f)
print('# TYPE node_mail_synth_trans gauge', file=f )

# check for time, if its been a week or so, rotate the log
logfile='/var/tmp/mail-tester.log'
if( need_to_rotate_log(logfile) ):
    print( 'Rotating log file, its a week old (deletes file from 2 weeks ago)' )
    shutil.move( logfile, logfile + '.1' )

# also set up an actual log file while I am learning python / testing this out
logging.basicConfig(filename=logfile, format='%(asctime)s - %(message)s', datefmt='%H:%M:%S %d-%m-%y', level=logging.INFO)

# all the time_ns() calls are just timestamps to compare back to this one for
# relative time elapsed for operations, good for graphing in prometheus
start_time = time.time_ns();
logging.info("start up for: %d" % nonce );

SendMessage( server, username, password, nonce, f )
logging.info("waiting 5 seconds for email to actually be delivered")
time.sleep(5)
ReceiveMessage( server, username, password, nonce, start_time, f )

Fail2BanCount()

# close output file (used for prometheus)
f.close()