#!/usr/bin/env python3

import argparse
import sys
import time
import traceback
from datetime import datetime, timedelta

import humanize

from checker import nagios
from checker.result import quit_check

sys.path.insert(0, "/usr/lib/python3/dist-packages")
import dbus


def check_timer(timer_name):
    if not timer_name.endswith('.timer'):
        timer_name = timer_name + '.timer'

    try:
        system_bus = dbus.SystemBus()
        systemd1 = system_bus.get_object('org.freedesktop.systemd1', '/org/freedesktop/systemd1')
        manager = dbus.Interface(systemd1, 'org.freedesktop.systemd1.Manager')
        timer_unit_path = manager.GetUnit(timer_name)
        timer_unit = system_bus.get_object('org.freedesktop.systemd1', timer_unit_path)
        timer_properties = dbus.Interface(timer_unit, 'org.freedesktop.DBus.Properties')
        active_state = timer_properties.Get('org.freedesktop.systemd1.Unit', 'ActiveState')
        if active_state == 'active':
            next_elapse = timer_properties.Get('org.freedesktop.systemd1.Timer', 'NextElapseUSecRealtime')

            try:
                local_timezone_offset_seconds = time.localtime().tm_gmtoff
                local_timezone_offset = timedelta(seconds=local_timezone_offset_seconds)
                local_datetime = datetime.utcfromtimestamp(int(next_elapse) / 1e6) + local_timezone_offset
                next_elapse_str = local_datetime.strftime("%m-%d-%Y %H:%M")
            except ValueError as v_err:
                if 'is out of range' in repr(v_err):
                    # This occurs whenever the timer resets.
                    # "year 586524 is out of range"
                    print(f'OK - {timer_name} has triggered.')
                    sys.exit(nagios.STATE_OK)

            current_time = time.time() * 1e6  # convert current time to microseconds
            remaining_time_sec = int((next_elapse - current_time) / 1e6)  # convert remaining time to seconds
            remaining_time_human = str(humanize.naturaltime(datetime.now() + timedelta(seconds=remaining_time_sec))).strip(' from now')
            perfdata_dict = {
                'remaining_time': {
                    'value': remaining_time_sec,
                    'unit': 's',
                    'min': 0
                }
            }
            quit_check(f'{timer_name} is active. Trigger time: {next_elapse_str}. Remaining time: {remaining_time_human}.', nagios.STATE_OK, perfdata_dict)
        else:
            quit_check(f'{timer_name} is not active.', nagios.STATE_CRIT)
    except dbus.exceptions.DBusException:
        quit_check(f'{timer_name} could not be found.', nagios.STATE_UNKNOWN)


if __name__ == '__main__':
    parser = argparse.ArgumentParser()
    parser.add_argument('-t', '--timer', required=True, help='The name of the timer to check.')
    parser.add_argument('-l', '--last-ran-delta', help='The associated service should have been triggered at least this many seconds ago.')
    args = parser.parse_args()

    try:
        check_timer(args.timer)
    except Exception as e:
        print(f'UNKNOWN - exception "{e}"')
        traceback.print_exc()
        sys.exit(nagios.STATE_UNKNOWN)