#!/usr/bin/env python3

import subprocess
from datetime import datetime, timedelta

import dateutil.parser
import pytz

states = {
    "OK": 0,
    "WARNING": 1,
    "CRITICAL": 2,
    "UNKNOWN": 3
}

def report(state: str, msg: str) -> None:
    print("%s: %s" % (state, msg))
    exit(states[state])

if subprocess.check_output(['psql', '-v', 'ON_ERROR_STOP=1',
                            'postgres', '-t', '-c',
                            'SELECT pg_is_in_recovery()']).strip() != b'f':
    report('OK', 'this is not the primary')

try:
    with open('/var/lib/nagios_state/last_postgres_backup') as f:
        last_backup = dateutil.parser.parse(f.read())
except OSError:
    report('UNKNOWN', 'could not determine completion time of last Postgres backup')

if datetime.now(tz=pytz.utc) - last_backup > timedelta(hours=25):
    report('CRITICAL', 'last Postgres backup completed more than 25 hours ago: %s' % (last_backup,))

report('OK', 'last Postgres backup completed less than 25 hours ago: %s' % (last_backup,))
