#! /usr/bin/python3
import calendar
import re
import sys
from dateutil.parser import parse
import datetime

def write_csv(downtimes, output):
    with open(output, 'w+') as f:
        i = 1
        for month in sorted(downtimes.keys()):
            f.write('Start,End,Downtime in seconds,Downtime,Planned?,Comment\n')
            i = i + 1
            first_row = i
            total_sec = downtimes[month]['days'] * 24 * 60 * 60
            for begin, end in downtimes[month]['downtimes']:
                sec = (end - begin).total_seconds()
                f.write('"=""%s""","=""%s""",%i,"=""%s""",No,\n' %
                        (begin,
                        end,
                        sec,
                        str(datetime.timedelta(seconds=sec)),
                        ))
                i = i + 1
            last_row = i - 1
            f.write('\nMonth,Downtime in seconds,Downtime in minutes,SLA\n')
            i = i + 2
            f.write('"=""%s""","=SUMIF(E%i:E%i,""No"",C%i:C%i)","=TEXT(TIME(INT(B%i/3600),MOD(INT(B%i/60),60),MOD(B%i, 60)), ""h:mm"")","=100-(((B%i)/%i)*100)"\n\n\n\n\n' % (month, first_row, last_row, first_row, last_row, i, i, i, i, total_sec))
            i = i + 5

def append_downtime(downtimes, begin, end):
    month = '%i/%02d' % (begin.year, begin.month)
    if month not in downtimes:
        _, days = calendar.monthrange(begin.year, begin.month)
        downtimes[month] = {'days': days, 'downtimes': []}
    downtimes[month]['downtimes'].append((begin, end))
    return downtimes


def parse_log(logfile):
    with open(logfile) as f:
        downtimes = {}
        for line in f:
            if 'Unavailable' in line:
                match = re.search(r'Unavailable ([0-9.]+) ([0-9:]+) - ([0-9.]+) ([0-9:]+)', line)
                if match:
                    begin = parse('%s %s' % (match.group(1), match.group(2)), dayfirst=True)
                    end = parse('%s %s' % (match.group(3), match.group(4)), dayfirst=True)
                    if begin.year == end.year and \
                            begin.month == end.month:
                                downtimes = append_downtime(downtimes, begin, end)
                    else:
                        _, last_day = calendar.monthrange(begin.year, begin.month)
                        end_of_month = parse('%s.%s.%s 23:59:59' % (last_day, begin.month, begin.year), dayfirst=True)
                        beginning_of_month = parse('01.%s.%s 00:00:00' % (end.month, end.year), dayfirst=True)
                        downtimes = append_downtime(downtimes, begin, end_of_month)
                        downtimes = append_downtime(downtimes, beginning_of_month, end)
        return downtimes

def main():
    if len(sys.argv) < 3:
        print('Usage: ./%s available.log destination.csv' % sys.argv[0])
        return 1
    downtimes = parse_log(sys.argv[1])
    write_csv(downtimes, sys.argv[2])

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