#!/usr/bin/python3
# Copyright (C) 2023 Philipp Fromme
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

import argparse
import pytz
import re
import subprocess
import sys
from enum import Enum
from datetime import datetime, timedelta

class State(Enum):
    OK = 0
    WARNING = 1
    CRITICAL = 2
    UNKNOWN = 3
    def set_state(self, state):
        if state.value > self.value:
            return state
        return self

def main():
	parser = argparse.ArgumentParser(description="Check for LVM snapshots overdue for deletion")
	parser.add_argument("-w", "--warning", help="Warning threshold, default "
	                   "604800 seconds (one week)", nargs="?", type=int,
	                   default=604800)
	parser.add_argument("-c", "--critical", help="Critical threshold, default 1209600 seconds (two weeks)",
	                   nargs="?", type=int, default=1209600)
	parser.add_argument("-z", "--tz", help="Set timezone, default Europe/Berlin",
	                   nargs="?", type=str, default='Europe/Berlin')
	parser.add_argument("-r", "--regex", help="Only show LVs with names matching regex, "
	                   "matches all snapshots by default", nargs='+', default=[None])
	parser.add_argument("-d", "--delete", help="Only show snapshots to be deleted",
	                   action="store_true")
	args = parser.parse_args()

	if args.critical < args.warning:
		sys.exit(f"Critical seconds {args.critical} is less than warning seconds {args.warning}")
	cmd = ['/sbin/lvs', '-o', 'lv_name,lv_time', '--separator=|', '--noheadings', '-S', 'lv_attr=~[^s.*]']
	snapshots = subprocess.check_output(cmd)
	snapshots = snapshots.decode().strip().split('\n')
	dt_now = datetime.now(pytz.timezone(args.tz))
	state = State.OK
	output = ""
	for line in snapshots:
		if not line:
			continue
		line = line.strip()
		elements = line.split('|')
		lv_name = elements[0]
		for pattern in args.regex:
			if pattern is None:
				break
			regex = re.compile(pattern)
			if regex.match(lv_name):
				break
		else:
			continue
		lv_time = elements[1]
		dt_lv_time = datetime.strptime(lv_time, '%Y-%m-%d %H:%M:%S %z')
		dt_warning = dt_lv_time + timedelta(0,args.warning)
		dt_critical = dt_lv_time + timedelta(0,args.critical)
		if dt_warning > dt_now and args.delete:
			continue
		output = (f"{output}\n"
			 f"{lv_name}:\n"
			 f"  Creation Date: {lv_time}\n"
			 f"  Deletion Date: {dt_warning}")
		dt_delta = None
		if dt_critical < dt_now:
			state = state.set_state(State.CRITICAL)
		elif dt_warning < dt_now:
			state = state.set_state(State.WARNING)
		else:
			continue
		dt_delta = dt_now - dt_warning
		output = (f"{output}\n"
			  f"  Deletion Overdue: {dt_delta}")
	if state == State.OK:
		output = ("OK: keine zu loeschenden Snapshots gefunden\n"
			 f"{output}")
	elif state == State.WARNING:
		output = ("WARNING: folgende Snapshots muessen geloescht werden!\n"
			 f"{output}")
	elif state == State.CRITICAL:
		output = ("CRITICAL: einige Snapshots sind bereits DEUTLICH ueber dem Loeschdatum!\n"
			 f"{output}")
	print(output)
	sys.exit(state.value)

if __name__ == "__main__":
    main()