#!/usr/bin/env python3
# -*- coding: utf-8 -*-
# Copyright (C) 2019 tribe29 GmbH - License: GNU General Public License v2
# This file is part of Checkmk (https://checkmk.com). It is subject to the terms and
# conditions defined in the file COPYING, which is part of this source code package.

#
# session_id, wait_duration_ms, wait_type, blocking_session_id
# <<<mssql_blocked_sessions>>>
# Blocked _Sessions
# 119 232292187 LCK_M_U 75
# 76 221526672 LCK_M_U 115

# <<<mssql_blocked_sessions:sep(124)>>>
# Blocked _Sessions
# 119|232292187|LCK_M_U|75
# 76|221526672|LCK_M_U|115

# <<<mssql_blocked_sessions:sep(124)>>>
# Blocked _Sessions
# INST_ID1|119|232292187|LCK_M_U|75
# INST_ID2|76|221526672|LCK_M_U|115

# <<<mssql_blocked_sessions:sept(124)>>>
# INST_ID1|No blocking sessions

factory_settings["mssql_blocked_sessions_default_levels"] = {
    "state": 2,
}

NO_BLOCKING_SESSIONS_MSG = "No blocking sessions"


def parse_mssql_blocked_sessions(info):
    db_instance = collections.namedtuple(  # pylint: disable=collections-namedtuple-call
        "DBInstance", ["session_id", "wait_type", "blocking_session_id", "wait_duration"]
    )
    parsed = {}
    for line in info:
        if line[-1].startswith("ERROR:"):
            continue

        if len(line) == 1 and line[0] == NO_BLOCKING_SESSIONS_MSG:
            parsed.setdefault("", [])
        elif len(line) == 2 and line[1] == NO_BLOCKING_SESSIONS_MSG:
            parsed.setdefault(line[0], [])
        elif len(line) == 4:
            session_id, wait_duration_ms, wait_type, blocking_session_id = line
            parsed.setdefault("", []).append(
                db_instance(
                    session_id,
                    wait_type,
                    blocking_session_id,
                    float(wait_duration_ms) / 1000,
                )
            )
        elif len(line) == 5:
            inst, session_id, wait_duration_ms, wait_type, blocking_session_id = line
            parsed.setdefault(inst, []).append(
                db_instance(
                    session_id,
                    wait_type,
                    blocking_session_id,
                    float(wait_duration_ms) / 1000,
                )
            )

    return parsed


def check_mssql_blocked_sessions(item, params, parsed):
    if item is None:
        item = ""

    data = parsed.get(item)
    if data is None:
        # Assume general connection problem to the database, which is reported
        # by the "X Instance" service and skip this check.
        raise MKCounterWrapped("Failed to retrieve data from database")
    if not data:
        yield 0, NO_BLOCKING_SESSIONS_MSG
        return

    summary = {}
    details = []
    warn, crit = params.get("waittime", (None, None))
    ignored_waittypes = set()
    waittypes_to_be_ignored = params.get("ignore_waittypes", [])

    for db_inst in data:
        if db_inst.wait_type in waittypes_to_be_ignored:
            ignored_waittypes.add(db_inst.wait_type)
            continue

        if crit is not None and db_inst.wait_duration >= crit:
            state = 2
        elif warn is not None and db_inst.wait_duration >= warn:
            state = 1
        else:
            state = 0

        summary.setdefault(db_inst.session_id, 0)
        summary[db_inst.session_id] += 1
        details.append(
            (
                state,
                "Session %s blocked by %s (Type: %s, Wait: %s)"
                % (
                    db_inst.session_id,
                    db_inst.blocking_session_id,
                    db_inst.wait_type,
                    get_age_human_readable(db_inst.wait_duration),
                ),
            )
        )

    if summary:
        yield params["state"], "Summary: %s" % (
            ", ".join(["%s blocked by %s ID(s)" % (k, v) for k, v in sorted(summary.items())])
        )

        max_state = max([state for state, _infotext in details])
        if max_state:
            yield max_state, "At least one session above thresholds (warn/crit at %s/%s)" % (
                get_age_human_readable(warn),
                get_age_human_readable(crit),
            )
        for state, infotext in details:
            yield state, "\n%s" % infotext
    else:
        yield 0, NO_BLOCKING_SESSIONS_MSG

    if ignored_waittypes:
        yield 0, "\nIgnored wait types: %s" % ", ".join(ignored_waittypes)


check_info["mssql_blocked_sessions"] = {
    "parse_function": parse_mssql_blocked_sessions,
    "inventory_function": discover(),
    "check_function": check_mssql_blocked_sessions,
    "service_description": "MSSQL %s Blocked Sessions",
    "group": "mssql_instance_blocked_sessions",
    "default_levels_variable": "mssql_blocked_sessions_default_levels",
}
