#!/usr/bin/env python3
# -*- coding: utf-8; py-indent-offset: 4 -*-
#
# Author:  Linuxfabrik GmbH, Zurich, Switzerland
# Contact: info (at) linuxfabrik (dot) ch
#          https://www.linuxfabrik.ch/
# License: The Unlicense, see LICENSE file.

# https://github.com/Linuxfabrik/monitoring-plugins/blob/main/CONTRIBUTING.md

"""See the check's README for more details."""

import argparse
import sys

import lib.args
import lib.base
import lib.db_mysql
import lib.human
from lib.globals import STATE_OK, STATE_UNKNOWN, STATE_WARN

__author__ = 'Linuxfabrik GmbH, Zurich/Switzerland'
__version__ = '2026040801'

DESCRIPTION = """Checks sort operations in MySQL/MariaDB, including the rate of sort merge passes that
required temporary disk files. A high rate indicates that sort_buffer_size may need to
be increased.
Alerts when the disk-based sort rate is too high."""

DEFAULT_DEFAULTS_FILE = '/var/spool/icinga2/.my.cnf'
DEFAULT_DEFAULTS_GROUP = 'client'
DEFAULT_TIMEOUT = 3


def parse_args():
    """Parse command line arguments using argparse."""
    parser = argparse.ArgumentParser(description=DESCRIPTION)

    parser.add_argument(
        '-V',
        '--version',
        action='version',
        version=f'%(prog)s: v{__version__} by {__author__}',
    )

    parser.add_argument(
        '--always-ok',
        help=lib.args.help('--always-ok'),
        dest='ALWAYS_OK',
        action='store_true',
        default=False,
    )

    parser.add_argument(
        '--defaults-file',
        help='MySQL/MariaDB cnf file to read user, host and password from. '
        'Example: `--defaults-file=/var/spool/icinga2/.my.cnf`. '
        'Default: %(default)s',
        dest='DEFAULTS_FILE',
        default=DEFAULT_DEFAULTS_FILE,
    )

    parser.add_argument(
        '--defaults-group',
        help=lib.args.help('--defaults-group') + ' Default: %(default)s',
        dest='DEFAULTS_GROUP',
        default=DEFAULT_DEFAULTS_GROUP,
    )

    parser.add_argument(
        '--timeout',
        help=lib.args.help('--timeout') + ' Default: %(default)s (seconds)',
        dest='TIMEOUT',
        type=int,
        default=DEFAULT_TIMEOUT,
    )

    args, _ = parser.parse_known_args()
    return args


def get_vars(conn):
    # Do not implement `get_all_vars()`, just fetch the ones we need for this check.
    # Without the GLOBAL modifier, SHOW VARIABLES displays the values that are used for
    # the current connection to MariaDB.
    sql = """
        show global variables
        where variable_name like 'read_rnd_buffer_size'
            or variable_name like 'sort_buffer_size'
            ;
          """
    return lib.base.coe(lib.db_mysql.select(conn, sql))


def get_status(conn):
    # Do not implement `get_all_vars()`, just fetch the ones we need for this check.
    # Without the GLOBAL modifier, SHOW STATUS displays the values that are used for
    # the current connection to MariaDB.
    sql = """
        show global status
        where variable_name like 'Sort_merge_passes'
            or variable_name like 'Sort_range'
            or variable_name like 'Sort_scan'
            ;
          """
    return lib.base.coe(lib.db_mysql.select(conn, sql))


def main():
    """The main function. This is where the magic happens."""

    # logic taken from mysqltuner.pl:mysql_stats(), section # Sorting, v1.9.8
    # including variable names

    # parse the command line
    try:
        args = parse_args()
    except SystemExit:
        sys.exit(STATE_UNKNOWN)

    mysql_connection = {
        'defaults_file': args.DEFAULTS_FILE,
        'defaults_group': args.DEFAULTS_GROUP,
        'timeout': args.TIMEOUT,
    }
    conn = lib.base.coe(lib.db_mysql.connect(mysql_connection))
    lib.base.coe(lib.db_mysql.check_select_privileges(conn))

    myvar = lib.db_mysql.lod2dict(get_vars(conn))
    mystat = lib.db_mysql.lod2dict(get_status(conn))
    lib.db_mysql.close(conn)

    # init some vars
    msg = ''
    state = STATE_OK
    perfdata = ''

    # calculations
    mycalc = {}
    mycalc['total_sorts'] = int(mystat['Sort_scan']) + int(mystat['Sort_range'])
    if mycalc['total_sorts'] > 0:
        mycalc['pct_temp_sort_table'] = round(
            int(mystat['Sort_merge_passes']) / int(mycalc['total_sorts']) * 100
        )
    else:
        mycalc['pct_temp_sort_table'] = 0

    # Sorting
    msg += (
        f'{lib.human.number2human(mystat["Sort_scan"])} sorts used a full table scan. '
    )
    if mycalc['total_sorts'] == 0:

        # build the message
        msg += 'No sort required temporary tables.'
    else:
        msg += (
            f'Sorts requiring temporary tables:'
            f' {mycalc["pct_temp_sort_table"]}%'
            f' ({lib.human.number2human(mystat["Sort_merge_passes"])}'
            f' temp sorts /'
            f' {lib.human.number2human(mycalc["total_sorts"])} sorts)'
        )
        if mycalc['pct_temp_sort_table'] > 10:
            sort_state = STATE_WARN
            state = lib.base.get_worst(state, sort_state)
            msg += (
                f'{lib.base.state2str(state, prefix=" ")}.'
                f' Set sort_buffer_size >'
                f' {myvar["sort_buffer_size"]}'
                f' and/or read_rnd_buffer_size >'
                f' {myvar["read_rnd_buffer_size"]}.'
            )
        else:
            msg += '.'

    perfdata += lib.base.get_perfdata(
        'mysql_read_rnd_buffer_size',
        myvar['read_rnd_buffer_size'],
        uom='B',
        _min=0,
    )
    perfdata += lib.base.get_perfdata(
        'mysql_sort_buffer_size',
        myvar['sort_buffer_size'],
        uom='B',
        _min=0,
    )

    perfdata += lib.base.get_perfdata(
        'mysql_sort_merge_passes',
        mystat['Sort_merge_passes'],
        uom='c',
        _min=0,
    )
    perfdata += lib.base.get_perfdata(
        'mysql_sort_range',
        mystat['Sort_range'],
        uom='c',
        _min=0,
    )
    perfdata += lib.base.get_perfdata(
        'mysql_sort_scan',
        mystat['Sort_scan'],
        uom='c',
        _min=0,
    )

    perfdata += lib.base.get_perfdata(
        'mysql_pct_temp_sort_table',
        mycalc['pct_temp_sort_table'],
        uom='%',
        _min=0,
        _max=100,
    )
    perfdata += lib.base.get_perfdata(
        'mysql_total_sorts',
        mycalc['total_sorts'],
        uom='c',
        _min=0,
    )

    # over and out
    lib.base.oao(msg, state, perfdata, always_ok=args.ALWAYS_OK)


if __name__ == '__main__':
    try:
        main()
    except Exception:
        lib.base.cu()
