#!/usr/bin/env python3
# pylint: disable=invalid-name
# pylint: enable=invalid-name
# pylint: disable=consider-using-f-string

"""Munin plugin to monitor systemd service status.

=head1 NAME

systemd_status - monitor systemd service status, including normal services,
mounts, hotplugs and socket activations

=head1 APPLICABLE SYSTEMS

Linux systems with systemd installed.

=head1 CONFIGURATION

No configuration is required for this plugin.

Warning level for systemd "failed" state is set to 0:0. If any of the services
enters "failed" state, Munin will emit warning.

Single service can be ignored by configuring it's value to "0":

  [systemd_status]
  env.fwupd_refresh_service 0

Normally this plugin monitors global system services. User services can be
monitored by manually adding softlink and config:

  ln -s /usr/share/munin/plugins/systemd_status \
    /etc/munin/plugins/systemd_status_b

  [systemd_status_b]
  user b
  env.monitor_user yes

=head1 AUTHOR

Kim B. Heino <b@bbbs.net>

=head1 LICENSE

GPLv2

=head1 MAGIC MARKERS

 #%# family=auto
 #%# capabilities=autoconf

=cut

"""

import os
import pwd
import re
import subprocess
import sys
import unicodedata


STATES = (
    'failed',
    'dead',
    'running',
    'exited',
    'active',
    'listening',
    'waiting',
    'plugged',
    'mounted',
)

USER = os.environ.get('monitor_user') in ('yes', '1')


def safename(name):
    """Return safe variable name."""
    # Convert ä->a as isalpha('ä') is true
    value = unicodedata.normalize('NFKD', name)
    value = value.encode('ASCII', 'ignore').decode('utf-8')

    # Remove non-alphanumeric chars
    return ''.join(char.lower() if char.isalnum() else '_' for char in value)


def config():
    """Autoconfig values."""
    if USER:
        print('graph_title systemd services for {}'.format(
            pwd.getpwuid(os.geteuid())[0]))
    else:
        print('graph_title systemd services')
    print('graph_vlabel Services')
    print('graph_category processes')
    print('graph_args --base 1000 --lower-limit 0')
    print('graph_scale no')
    print('graph_info Number of services in given activation state.')
    for state in STATES:
        print('{state}.label Services in {state} state'.format(state=state))
    print('failed.warning 0:0')
    if os.environ.get('MUNIN_CAP_DIRTYCONFIG') == '1':
        fetch()


def fetch():
    """Print runtime values."""
    # Get data
    try:
        output = subprocess.check_output(['systemctl', 'list-units'] +
                                         (['--user'] if USER else []),
                                         encoding='utf-8')
    except (OSError, subprocess.CalledProcessError):
        return

    # Parse data
    states = {state: 0 for state in STATES}
    for line in output.splitlines():
        token = line.split()
        if token and len(token[0]) < 3:  # Skip failed-bullet
            token = token[1:]
        if len(token) < 4:
            continue
        service = token[0]
        state = token[3]
        if service.endswith('.scope'):
            continue  # Ignore scopes
        if re.match(r'user.*@\d+\.service', service):
            continue  # These fail randomly in older systemd
        if state in states:
            value = 1
            if state == 'failed':
                value = int(os.environ.get(safename(service), 1))
            states[state] += value

    # Output
    for state in STATES:
        print('{}.value {}'.format(state, states[state]))


def fix_dbus():
    """Fix DBus address for user service."""
    if not USER:
        return
    euid = '/{}/'.format(os.geteuid())
    if euid in os.environ.get('DBUS_SESSION_BUS_ADDRESS', ''):
        return
    os.putenv('DBUS_SESSION_BUS_ADDRESS',
              'unix:path=/run/user{}bus'.format(euid))


if __name__ == '__main__':
    fix_dbus()
    if len(sys.argv) > 1 and sys.argv[1] == 'autoconf':
        print('yes' if os.path.exists('/run/systemd/system') else
              'no (systemd is not running)')
    elif len(sys.argv) > 1 and sys.argv[1] == 'config':
        config()
    else:
        fetch()