#!/usr/bin/env python3

from datetime import datetime, timedelta
from re import match
from subprocess import check_output
from sys import exit

output = check_output(['zfs', 'get', 'creation', '-Hpr', '-t', 'snapshot'])

now = int(datetime.now().timestamp())
warn_age = now - (60 * 60 * 24 * 60)
crit_age = now - (60 * 60 * 24 * 90)

warn_snapshots = set()
crit_snapshots = set()

return_code = 0

for line in output.decode('utf-8').split("\n"):
    if line.strip() == '':
        continue

    items = line.split("\t")

    # If the snapshot name contains 'zfs-auto-snap', it's probably
    # really an automated snapshot and will be cleaned up eventually.
    # This check only cares about manually created snapshots, though.
    if 'zfs-auto-snap' in items[0]:
        continue

    # These are docker-internal snapshots and should not be touched by
    # us.
    if match(r'^tank/docker/[a-z0-9]+(-init)?@[0-9]+', items[0]):
        continue

    # line should be '<snapshot> creation <timestamp> -', separated by
    # tabstops.
    if len(items) < 3:
        print('UNKNOWN - error while parsing ' + line)
        exit(3)

    creation_date = int(items[2])

    if creation_date < crit_age:
        crit_snapshots.add(items[0])
    elif creation_date < warn_age:
        warn_snapshots.add(items[0])

# We have to do additional loops in here to have CRITICAL items on top.
for snap in sorted(crit_snapshots):
    print('CRITICAL - {} is older than 90 days'.format(snap))

for snap in sorted(warn_snapshots):
    print('WARN - {} is older than 60 days'.format(snap))

if len(crit_snapshots) > 0:
    return_code = 2
elif len(warn_snapshots) > 0:
    return_code = 1
else:
    print('OK - no snapshots are older than 60 days')

exit(return_code)