#!/usr/bin/env python

# Author: Josh Holtrop
# Simple script to show me my week's hours as far as my Ubuntu box knows them

import sys
import re
import argparse
from datetime import *

LOGFILE = '/var/log/auth.log'

now = datetime.now()
monday = (now - timedelta(now.weekday())).date()

def get_dt_from_log_line(line):
    m = re.match(r'(\S\S\S)\s+(\d+)\s+(\d+):(\d+):(\d+)\s+.*', line)
    if m is not None:
        month_name, day, t_hr, t_min, t_sec = m.group(1, 2, 3, 4, 5)
        try:
            month = datetime.strptime(month_name, '%b').month
        except:
            return None
        year = now.year
        if month == 12 and now.month == 1:
            year -= 1
        dt = datetime(*map(int, [year, month, day, t_hr, t_min, t_sec]))
        return dt
    return None

def main(argv):
    total_hours = 40
    parser = argparse.ArgumentParser('hours')
    parser.add_argument('-t', '--total', type=float)
    args = parser.parse_args(argv[1:])
    if args.total is not None:
        total_hours = args.total

    times = []
    for i in range(7):
        times.append([None, None])

    f = open(LOGFILE, 'r')
    while True:
        line = f.readline()
        if line == '':
            break
        if re.search(r'gnome-screensaver.*unlocked.login.keyring', line):
            # found a login line
            dt = get_dt_from_log_line(line)
            idx = (dt.date() - monday).days
            if times[idx][0] is None or dt < times[idx][0]:
                times[idx][0] = dt
        elif re.search(r'lock-screen:', line):
            # found a logout line
            dt = get_dt_from_log_line(line)
            idx = (dt.date() - monday).days
            if times[idx][1] is None or dt > times[idx][1]:
                times[idx][1] = dt
    f.close()

    now_idx = (now.date() - monday).days
    if times[now_idx][1] is None or now > times[now_idx][1]:
        times[now_idx][1] = now

    def fmt_time_dt(dt):
        s = dt.strftime('%I:%M') + dt.strftime('%p')[0].lower()
        if s[0] == '0':
            s = s[1:]
        return s

    border = lambda: sys.stdout.write('-' * 40 + '\n')

    total_seconds = 0
    border()
    for time in times:
        if time[0] is not None:
            sys.stdout.write('%-14s' % (time[0].strftime('%d %A') + ':'))
            sys.stdout.write(fmt_time_dt(time[0]))
            sys.stdout.write(' - ')
            if time[1] is not None:
                sys.stdout.write(fmt_time_dt(time[1]))
                seconds = (time[1] - time[0]).seconds
                hours = seconds / 60.0 / 60.0
                sys.stdout.write(' (%.2f hours)' % hours)
                total_seconds += seconds
            else:
                sys.stdout.write('???')
            sys.stdout.write('\n')
    border()
    sys.stdout.write('Total: %.2f hours' % (seconds / 60.0 / 60.0))

    secs_in_total_hours = total_hours * 60 * 60
    if total_seconds < secs_in_total_hours:
        out_time = now + timedelta(0, secs_in_total_hours - total_seconds)
        sys.stdout.write('; %.1f at: %s %s' % (total_hours,
            out_time.strftime('%a %d'), fmt_time_dt(out_time)))
    sys.stdout.write('\n')

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