#!/usr/bin/env python
# Slack

# -*- coding: utf-8 -*-
# +------------------------------------------------------------------+
# |             ____ _               _        __  __ _  __           |
# |            / ___| |__   ___  ___| | __   |  \/  | |/ /           |
# |           | |   | '_ \ / _ \/ __| |/ /   | |\/| | ' /            |
# |           | |___| | | |  __/ (__|   <    | |  | | . \            |
# |            \____|_| |_|\___|\___|_|\_\___|_|  |_|_|\_\           |
# |                                                                  |
# | Copyright Mathias Kettner 2018             mk@mathias-kettner.de |
# +------------------------------------------------------------------+
#
# This file is part of Check_MK.
# The official homepage is at http://mathias-kettner.de/check_mk.
#
# check_mk 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 in version 2.  check_mk is  distributed
# in the hope that it will be useful, but WITHOUT ANY WARRANTY;  with-
# out even the implied warranty of  MERCHANTABILITY  or  FITNESS FOR A
# PARTICULAR PURPOSE. See the  GNU General Public License for more de-
# tails. You should have  received  a copy of the  GNU  General Public
# License along with GNU Make; see the file  COPYING.  If  not,  write
# to the Free Software Foundation, Inc., 51 Franklin St,  Fifth Floor,
# Boston, MA 02110-1301 USA.
r"""
Send notification messages to Slack
===================================

Use a slack webhook to send notification messages
"""
from __future__ import unicode_literals
import sys
import requests
import re
import os

from typing import AnyStr, Dict, Optional, Tuple  # pylint: disable=unused-import

import cmk.password_store

COLORS = {
    "CRITICAL": "#EE0000",
    "DOWN": "#EE0000",
    "WARNING": "#FFDD00",
    "OK": "#00CC00",
    "UP": "#00CC00",
    "UNKNOWN": "#CCCCCC",
    "UNREACHABLE": "#CCCCCC",
}


def cmk_links(context):
    # type: (Dict) -> Tuple[Optional[str], Optional[str]]
    if context.get("PARAMETER_URL_PREFIX"):
        url_prefix = context["PARAMETER_URL_PREFIX"]
    elif context.get("PARAMETER_URL_PREFIX_MANUAL"):
        url_prefix = context["PARAMETER_URL_PREFIX_MANUAL"]
    elif context.get("PARAMETER_URL_PREFIX_AUTOMATIC") == "http":
        url_prefix = "http://%s/%s" % (context["MONITORING_HOST"], context["OMD_SITE"])
    elif context.get("PARAMETER_URL_PREFIX_AUTOMATIC") == "https":
        url_prefix = "https://%s/%s" % (context["MONITORING_HOST"], context["OMD_SITE"])
    else:
        url_prefix = None

    if url_prefix:
        base_url = re.sub('/check_mk/?', '', url_prefix)
        host_url = base_url + context['HOSTURL']

        if context['WHAT'] == 'SERVICE':
            service_url = base_url + context['SERVICEURL']
            return host_url, service_url

        return host_url, None

    return None, None


def extend_context_with_link_urls(context, link_template):
    # type: (Dict, AnyStr) -> None

    host_url, service_url = cmk_links(context)

    if host_url:
        context['LINKEDHOSTNAME'] = link_template.format(host_url, context['HOSTNAME'])
    else:
        context['LINKEDHOSTNAME'] = context['HOSTNAME']

    if service_url:
        context['LINKEDSERVICEDESC'] = link_template.format(service_url, context['SERVICEDESC'])
    else:
        context['LINKEDSERVICEDESC'] = context.get('SERVICEDESC', '')


def slack_msg(context):
    # type: (Dict) -> Dict
    """Build the message for slack"""

    extend_context_with_link_urls(context, '<{}|{}>')

    if context.get('WHAT', None) == "SERVICE":
        color = COLORS.get(context["SERVICESTATE"])
        title = "Service {NOTIFICATIONTYPE} notification".format(**context)
        text = "Host: {LINKEDHOSTNAME} (IP: {HOSTADDRESS})\nService: {LINKEDSERVICEDESC}\nState: {SERVICESTATE}".format(
            **context)
        output = context["SERVICEOUTPUT"]
    else:
        color = COLORS.get(context["HOSTSTATE"])
        title = "Host {NOTIFICATIONTYPE} notification".format(**context)
        text = "Host: {LINKEDHOSTNAME} (IP: {HOSTADDRESS})\nState: {HOSTSTATE}".format(**context)
        output = context["HOSTOUTPUT"]

    return {
        "attachments": [
            {
                "color": color,
                "title": title,
                "text": text,
            },
            {
                "color":
                    color,
                "title":
                    "Additional Info",
                "text":
                    output + "\nPlease take a look: " + ", ".join(
                        map("@{}".format, context["CONTACTNAME"].split(','))),
                "footer":
                    "Check_MK notification: {LONGDATETIME}".format(**context),
            },
        ]
    }


def collect_context():
    # type: () -> Dict
    return {
        var[7:]: value.decode("utf-8")
        for (var, value) in os.environ.items()
        if var.startswith("NOTIFY_")
    }


def retrieve_from_passwordstore(parameter):
    value = parameter.split()

    if len(value) == 2:
        if value[0] == 'store':
            value = cmk.password_store.load().get(value[1])
        else:
            value = value[1]
    else:
        value = value[0]

    return value


def post_request(message_constructor, success_code=200):
    context = collect_context()

    url = retrieve_from_passwordstore(context.get("PARAMETER_WEBHOOK_URL"))

    r = requests.post(url=url, json=message_constructor(context))

    if r.status_code == success_code:
        sys.exit(0)
    else:
        sys.stderr.write(
            "Failed to send notification. Status: %i, Response: %s\n" % (r.status_code, r.text))
        sys.exit(2)


if __name__ == "__main__":
    post_request(slack_msg)