#!/usr/bin/env python3
#
# Copyright (c) 2017-2020  Joe Clarke <jclarke@cisco.com>
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
# 1. Redistributions of source code must retain the above copyright
#    notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
#    notice, this list of conditions and the following disclaimer in the
#    documentation and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
# SUCH DAMAGE.

import sys
import json
from sparker import Sparker, MessageType
from subprocess import Popen, PIPE
import re
import shlex
import requests
import os
from multiprocessing import Pool
import CLEUCreds
from cleu.config import Config as C

SPARK_ROOM = "DHCP Scope Alarms"

THRESHOLD = "75"
CACHE_FILE = "/home/jclarke/dhcp_scope.dat"
STATS_FILE = "/home/jclarke/dhcp_scope_stats.dat"


def parse_result(out):
    matches = re.findall(r"([\w-]+=[^;]+);(?=\s|$)", out)
    res = {}
    for m in matches:
        if m == "":
            continue
        k, v = m.split("=")
        res[k] = v
    return res


def get_results(scope):
    global DHCP_SERVER

    if scope != "100 Ok" and scope != "":
        proc = Popen(
            shlex.split("ssh -2 root@{} /root/nrcmd.sh -r scope {} getUtilization".format(C.DHCP_SERVER, scope)), stdout=PIPE, stderr=PIPE
        )
        out, err = proc.communicate()
        outs = out.decode("utf-8")
        if not re.search(r"^100", outs):
            return None
        outd = parse_result(outs)
        if "active-dynamic" not in outd or "total-dynamic" not in outd or "free-dynamic" not in outd:
            return None

        util = (float(outd["active-dynamic"]) / float(outd["total-dynamic"])) * 100.0
        # print('Util for {0} is {1:.2f}% utilized'.format(scope, util))

        return (scope, {"util": util, "active-dynamic": outd["active-dynamic"], "total-dynamic": outd["total-dynamic"]})


def get_metrics(pool):
    global DHCP_SERVER

    response = {}

    proc = Popen(shlex.split("ssh -2 root@{} /root/nrcmd.sh -r scope listnames".format(C.DHCP_SERVER)), stdout=PIPE, stderr=PIPE)
    out, err = proc.communicate()
    outs = out.decode("utf-8")
    if not re.search(r"^100", outs):
        sys.exit(0)
    scopes = outs.split("\n")

    results = [pool.apply_async(get_results, [s]) for s in scopes]
    for res in results:
        retval = res.get()
        if retval is not None:
            response[retval[0]] = retval[1]

    return response


if __name__ == "__main__":
    prev_state = {}
    curr_state = {}
    stats = {}

    spark = Sparker(token=CLEUCreds.SPARK_TOKEN)

    if os.path.exists(CACHE_FILE):
        fd = open(CACHE_FILE, "r")
        prev_state = json.load(fd)
        fd.close()

    pool = Pool(20)
    metrics = get_metrics(pool)

    for scope, stat in metrics.items():
        stats[scope] = {"perc": stat["util"]}
        if stat["util"] >= float(THRESHOLD):
            curr_state[scope] = True
            if scope not in prev_state or (scope in prev_state and not prev_state[scope]):
                spark.post_to_spark(
                    C.WEBEX_TAM,
                    SPARK_ROOM,
                    "Scope **{0}** is now **{1:.2f}%** utilized ({2} of {3} free addresses remain); suppressing future alerts until resolved".format(
                        scope, stat["util"], stat["free-dynamic"], stat["total-dynamic"]
                    ),
                    MessageType.WARNING,
                )
        else:
            curr_state[scope] = False
            if scope in prev_state and prev_state[scope]:
                spark.post_to_spark(
                    C.WEBEX_TEAM,
                    SPARK_ROOM,
                    "Scope **{0}** is now only **{1:.2f}%** utilized ({2} free addresses out of {3})".format(
                        scope, stat["util"], stat["free-dynamic"], stat["total-dynamic"]
                    ),
                    MessageType.GOOD,
                )

    fd = open(CACHE_FILE, "w")
    json.dump(curr_state, fd, indent=4)
    fd.close()

    fd = open(STATS_FILE, "w")
    json.dump(stats, fd, indent=4)
    fd.close()