#!/usr/bin/python

from collections import Counter
from sys import version_info
import datetime
import argparse
import getpass
import smtplib
import time
import sys
import os
import re

py3 = version_info[0] > 2  # creates boolean value for test that Python major version > 2
username = False
password = False


def main():
    """
    Main method that gets called when script is executed

    :return: void
    """

    parser = argparse.ArgumentParser(description=("Parses provided log file and sends an email if a pattern is noticed "
                                                  "to repeat R times in M amount of minutes."))
    parser.add_argument("logfile", type=file, help="Log file to parse")
    parser.add_argument("-r", "--repeat", type=int, help="Number of times pattern can repeat")
    parser.add_argument("-m", "--minutes", type=int, help="Time in minutes that pattern will be monitored")

    args = parser.parse_args()
    logfile = args.logfile
    repeat = abs(args.repeat)
    minutes = abs(args.minutes)

    if not repeat:
        print "Please provide number of pattern accurrences to monitor for: -r INT"
        sys.exit(0)
    if not minutes:
        print "Please provide number of minutes to monitor a pattern for: -m INT"
        sys.exit(0)

    patterns = []
    first_time = 0
    for qline in readlines_reverse(logfile):
        # lets get time from the qline
        match = re.findall(r"\[(.{26}).+(\{.+\})", qline)

        time_string = match[0][0]
        log_time = datetime.datetime.strptime(time_string, "%Y-%m-%dT%H:%M:%S.%f").timetuple()

        if first_time == 0:
            first_time = int(time.mktime(log_time))

        pattern_string = match[0][1]
        patterns.append(pattern_string)

        # lets check stop condition
        if (first_time - int(time.mktime(log_time))) >= minutes*60:
            # reset first time
            first_time = 0
            # count number of times every pattern appears in list
            counts = Counter(patterns)
            for key, value in counts.iteritems():
                if value >= repeat:
                    # we need to send email now
                    global username, password

                    while not username:
                        if py3:
                            username = input("Please enter your Gmail username: ")
                        else:
                            username = raw_input("Please enter your Gmail username: ")

                    while not password:
                        password = getpass.getpass("Please enter your Gmail password: ")
                    print "Pattern: " + key + "\n"\
                          "appeared more than " + str(repeat) + " times in " + str(minutes) + " minutes. " \
                                                                                              "Sending email now."

                    send_mail("realmathtutor@gmail.com", "okryshchenko@gmail.com", "log parser report",
                              "The pattern has been noticed to repeat " + str(repeat) + " times in " + str(minutes),
                              "smtp.gmail.com")

            # reset patterns list
            patterns = []


def readlines_reverse(filename):
    """
    Reads file from the end to the top

    :param filename: file to read
    :return: list
    """

    with filename as qfile:
        qfile.seek(0, os.SEEK_END)
        position = qfile.tell()
        line = ''
        while position >= 0:
            qfile.seek(position)
            next_char = qfile.read(1)
            if next_char == "\n":
                yield line[::-1]
                line = ''
            else:
                line += next_char
            position -= 1
        yield line[::-1]


def send_mail(from_address, to_address, subject, text, server):
    """
    This function send emails

    :param from_address: who send the email
    :param to_address: recipient of the email
    :param subject: email subject
    :param text: email body message
    :param server: smtp server
    :return: void
    """

    message = """\
        From: %s
        To: %s
        Subject: %s
        %s
        """ % (from_address, ", ".join(to_address), subject, text)
    # Send the mail
    server = smtplib.SMTP(server, 587)
    server.ehlo()
    server.starttls()
    server.login(username, password)
    server.sendmail(from_address, to_address, message)
    server.quit()


if __name__ == '__main__':
    sys.exit(main())