#!/usr/bin/env python3
"""
=head1 NAME

mongo_lag - MongoDB Replication Lag

Connects to a single mongo instance and retrieve replication lag for all connected members.

=head1 APPLICABLE SYSTEMS

MongoDB 3.X and 4.X with pymongo installed.

=head1 CONFIGURATION

Default for host is 127.0.0.1 and port 27017 and will work without being defined:

    [mongo_lag]
    env.host 127.0.0.1
    env.port 27017
    env.username user
    env.password P@55w0rd

or

    [mongo_lag]
    env.MONGO_DB_URI mongodb://user:passwd@127.0.0.1:27017

=head1 AUTHOR

Stefan Andersen <stefan@stefanandersen.dk>

Updated by Alban Espie-Guillon <alban.espie@alterway.fr>

=head1 LICENSE

The Beer Ware License (Revision 42)
<alban.espie@alterway.fr> wrote this file. As long
as you retain this notice you can do whatever you want
with this stuff. If we meet some day, and you think
this stuff is worth it, you can buy me a beer in return.

SPDX-License-Identifier: Beerware

=cut
"""

import os
import sys
import pymongo

def _get_members():
    if 'MONGO_DB_URI' in os.environ:
        conn = pymongo.MongoClient(os.environ['MONGO_DB_URI'])
    else:
        host = os.environ.get('host', '127.0.0.1')
        port = os.environ.get('port', 27017)
        username = os.environ.get('username', '')
        password = os.environ.get('password', '')
        conn = pymongo.MongoClient(host, int(port))
        if username:
            connAuth = conn['admin']
            connAuth.authenticate(username, password)

    repl_status = conn.admin.command("replSetGetStatus")

    members = {}
    for member in repl_status['members']:
        if member['stateStr'] != 'ARBITER' :
            name = member['name'].split('.')[0]
            members[name] = {'state': member['state'], 'optimeDate': member['optimeDate']}
    return members

def run():
    members = _get_members();
    for member in members:
        if members[member]['state'] == 1:
            primary_optime = members[member]['optimeDate']

    for member in members:
        lag = (primary_optime - members[member]['optimeDate']).seconds
        print("{0}.value {1}".format(member, lag))

def config():
    print("""graph_title MongoDB replication lag
graph_args --base 1000
graph_vlabel Replication lag (seconds)
graph_category %s
""" % os.getenv('graph_category', 'db'))

    for member in _get_members():
        print("{0}.label {0}".format(member))

if __name__ == "__main__":
    if len(sys.argv) > 1 and sys.argv[1] == "config":
        config()
    else:
        run()