#!/usr/local/bin/python2.7
"""
 discovery-wrapper A small tool which wraps around discovery and tries to
                guide the discovery process with a more modern approach with a
                Queue and workers.

 Based on the original version of poller-wrapper.py by Job Snijders

 Author:        Neil Lathwood <neil@librenms.org>
 Date:          Sep 2016

 Usage:         This program accepts one command line argument: the number of threads
                that should run simultaneously. If no argument is given it will assume
                a default of 1 thread.

 Ubuntu Linux:  apt-get install python-mysqldb
 FreeBSD:       cd /usr/ports/*/py-MySQLdb && make install clean

 License:       This program 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, either version 3 of the License, or (at your
                option) any later version.

                This program is distributed in the hope that it will be useful, but
                WITHOUT ANY WARRANTY; without even the implied warranty of
                MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
                Public License for more details.

                You should have received a copy of the GNU General Public License along
                with this program. If not, see http://www.gnu.org/licenses/.

                LICENSE.txt contains a copy of the full GPLv3 licensing conditions.
"""
try:

    import json
    import os
    import Queue
    import subprocess
    import sys
    import threading
    import time

except:
    print "ERROR: missing one or more of the following python modules:"
    print "threading, Queue, sys, subprocess, time, os, json"
    sys.exit(2)

try:
    import MySQLdb
except:
    print "ERROR: missing the mysql python module:"
    print "On ubuntu: apt-get install python-mysqldb"
    print "On FreeBSD: cd /usr/ports/*/py-MySQLdb && make install clean"
    sys.exit(2)

"""
    Fetch configuration details from the config_to_json.php script
"""

install_dir = os.path.dirname(os.path.realpath(__file__))
config_file = install_dir + '/config.php'


def get_config_data():
    config_cmd = ['/usr/bin/env', 'php', '%s/config_to_json.php' % install_dir]
    try:
        proc = subprocess.Popen(config_cmd, stdout=subprocess.PIPE, stdin=subprocess.PIPE)
    except:
        print "ERROR: Could not execute: %s" % config_cmd
        sys.exit(2)
    return proc.communicate()[0]

try:
    with open(config_file) as f:
        pass
except IOError as e:
    print "ERROR: Oh dear... %s does not seem readable" % config_file
    sys.exit(2)

try:
    config = json.loads(get_config_data())
except:
    print "ERROR: Could not load or parse configuration, are PATHs correct?"
    sys.exit(2)

discovery_path = config['install_dir'] + '/discovery.php'
db_username = config['db_user']
db_password = config['db_pass']
db_port = int(config['db_port'])

if config['db_host'][:5].lower() == 'unix:':
    db_server = config['db_host']
    db_port = 0
else:
    db_server = config['db_host']

db_dbname = config['db_name']


def db_open():
    try:
        if db_port == 0:
            db = MySQLdb.connect(host=db_server, user=db_username, passwd=db_password, db=db_dbname)
        else:
            db = MySQLdb.connect(host=db_server, port=db_port, user=db_username, passwd=db_password, db=db_dbname)
        return db
    except:
        print "ERROR: Could not connect to MySQL database!"
        sys.exit(2)

# (c) 2015, GPLv3, Daniel Preussker <f0o@devilcode.org> <<<EOC1
if 'distributed_poller_group' in config:
    discovery_group = str(config['distributed_poller_group'])
else:
    discovery_group = False


def memc_alive():
    try:
        global memc
        key = str(uuid.uuid4())
        memc.set('discovery.ping.' + key, key, 60)
        if memc.get('discovery.ping.' + key) == key:
            memc.delete('discovery.ping.' + key)
            return True
        else:
            return False
    except:
        return False


def memc_touch(key, time):
    try:
        global memc
        val = memc.get(key)
        memc.set(key, val, time)
    except:
        pass

if ('distributed_poller' in config and
    'distributed_poller_memcached_host' in config and
    'distributed_poller_memcached_port' in config and
        config['distributed_poller']):
    try:
        import memcache
        import uuid
        memc = memcache.Client([config['distributed_poller_memcached_host'] + ':' +
            str(config['distributed_poller_memcached_port'])])
        if str(memc.get("discovery.master")) == config['distributed_poller_name']:
            print "This system is already joined as the discovery master."
            sys.exit(2)
        if memc_alive():
            if memc.get("discovery.master") is None:
                print "Registered as Master"
                memc.set("discovery.master", config['distributed_poller_name'], 10)
                memc.set("discovery.nodes", 0, 300)
                IsNode = False
            else:
                print "Registered as Node joining Master %s" % memc.get("discovery.master")
                IsNode = True
                memc.incr("discovery.nodes")
            distdisco = True
        else:
            print "Could not connect to memcached, disabling distributed discovery."
            distdisco = False
            IsNode = False
    except SystemExit:
        raise
    except ImportError:
        print "ERROR: missing memcache python module:"
        print "On deb systems: apt-get install python-memcache"
        print "On other systems: easy_install python-memcached"
        print "Disabling distributed discovery."
        distdisco = False
else:
    distdisco = False
# EOC1

s_time = time.time()
real_duration = 0
per_device_duration = {}
discovered_devices = 0

"""
    Take the amount of threads we want to run in parallel from the commandline
    if None are given or the argument was garbage, fall back to default of 16
"""
try:
    amount_of_workers = int(sys.argv[1])
    if amount_of_workers == 0:
        print "ERROR: 0 threads is not a valid value"
        sys.exit(2)
except:
    amount_of_workers = 1

devices_list = []

"""
    This query specificly orders the results depending on the last_discovered_timetaken variable
    Because this way, we put the devices likely to be slow, in the top of the queue
    thus greatening our chances of completing _all_ the work in exactly the time it takes to
    discover the slowest device! cool stuff he
"""
# (c) 2015, GPLv3, Daniel Preussker <f0o@devilcode.org> <<<EOC2
if discovery_group is not False:
    query = "select device_id from devices where poller_group IN(" + discovery_group + ") and disabled = 0 order by last_polled_timetaken desc"
else:
    query = "select device_id from devices where disabled = 0 order by last_polled_timetaken desc"
# EOC2


db = db_open()
cursor = db.cursor()
cursor.execute(query)
devices = cursor.fetchall()
for row in devices:
    devices_list.append(int(row[0]))
# (c) 2015, GPLv3, Daniel Preussker <f0o@devilcode.org> <<<EOC3
if distdisco and not IsNode:
    query = "select max(device_id),min(device_id) from devices"
    cursor.execute(query)
    devices = cursor.fetchall()
    maxlocks = devices[0][0]
    minlocks = devices[0][1]
# EOC3
db.close()

"""
    A seperate queue and a single worker for printing information to the screen prevents
    the good old joke:

        Some people, when confronted with a problem, think,
        "I know, I'll use threads," and then they two they hav erpoblesms.
"""


def printworker():
    nodeso = 0
    while True:
# (c) 2015, GPLv3, Daniel Preussker <f0o@devilcode.org> <<<EOC4
        global IsNode
        global distdisco
        if distdisco:
            if not IsNode:
                memc_touch('discovery.master', 10)
                nodes = memc.get('discovery.nodes')
                if nodes is None and not memc_alive():
                    print "WARNING: Lost Memcached. Taking over all devices. Nodes will quit shortly."
                    distdisco = False
                    nodes = nodeso
                if nodes is not nodeso:
                    print "INFO: %s Node(s) Total" % (nodes)
                    nodeso = nodes
            else:
                memc_touch('discovery.nodes', 10)
            try:
                worker_id, device_id, elapsed_time = print_queue.get(False)
            except:
                pass
                try:
                    time.sleep(1)
                except:
                    pass
                continue
        else:
            worker_id, device_id, elapsed_time = print_queue.get()
# EOC4
        global real_duration
        global per_device_duration
        global discovered_devices
        real_duration += elapsed_time
        per_device_duration[device_id] = elapsed_time
        discovered_devices += 1
        if elapsed_time < 300:
            print "INFO: worker %s finished device %s in %s seconds" % (worker_id, device_id, elapsed_time)
        else:
            print "WARNING: worker %s finished device %s in %s seconds" % (worker_id, device_id, elapsed_time)
        print_queue.task_done()

"""
    This class will fork off single instances of the discovery.php process, record
    how long it takes, and push the resulting reports to the printer queue
"""


def poll_worker():
    while True:
        device_id = poll_queue.get()
# (c) 2015, GPLv3, Daniel Preussker <f0o@devilcode.org> <<<EOC5
        if not distdisco or memc.get('discovery.device.' + str(device_id)) is None:
            if distdisco:
                result = memc.add('discovery.device.' + str(device_id), config['distributed_poller_name'], 300)
                if not result:
                    print "This device (%s) appears to be being discovered by another discovery node" % (device_id)
                    poll_queue.task_done()
                    continue
                if not memc_alive() and IsNode:
                    print "Lost Memcached, Not discovering Device %s as Node. Master will discover it." % device_id
                    poll_queue.task_done()
                    continue
# EOC5
            try:
                start_time = time.time()
                command = "/usr/bin/env php %s -h %s >> /dev/null 2>&1" % (discovery_path, device_id)
                subprocess.check_call(command, shell=True)
                elapsed_time = int(time.time() - start_time)
                print_queue.put([threading.current_thread().name, device_id, elapsed_time])
            except (KeyboardInterrupt, SystemExit):
                raise
            except:
                pass
        poll_queue.task_done()

poll_queue = Queue.Queue()
print_queue = Queue.Queue()

print "INFO: starting the discovery at %s with %s threads, slowest devices first" % (time.strftime("%Y-%m-%d %H:%M:%S"),
        amount_of_workers)

for device_id in devices_list:
    poll_queue.put(device_id)

for i in range(amount_of_workers):
    t = threading.Thread(target=poll_worker)
    t.setDaemon(True)
    t.start()

p = threading.Thread(target=printworker)
p.setDaemon(True)
p.start()

try:
    poll_queue.join()
    print_queue.join()
except (KeyboardInterrupt, SystemExit):
    raise

total_time = int(time.time() - s_time)

print "INFO: discovery-wrapper polled %s devices in %s seconds with %s workers" % (discovered_devices, total_time, amount_of_workers)

# (c) 2015, GPLv3, Daniel Preussker <f0o@devilcode.org> <<<EOC6
if distdisco or memc_alive():
    master = memc.get("discovery.master")
    if master == config['distributed_poller_name'] and not IsNode:
        print "Wait for all discovery-nodes to finish"
        nodes = memc.get("discovery.nodes")
        while nodes > 0 and nodes is not None:
            try:
                time.sleep(1)
                nodes = memc.get("discovery.nodes")
            except:
                pass
        print "Clearing Locks"
        x = minlocks
        while x <= maxlocks:
            memc.delete('discovery.device.' + str(x))
            x = x + 1
        print "%s Locks Cleared" % x
        print "Clearing Nodes"
        memc.delete("discovery.master")
        memc.delete("discovery.nodes")
    else:
        memc.decr("discovery.nodes")
    print "Finished %s." % time.time()
# EOC6

show_stopper = False

if total_time > 21600:
    print "WARNING: the process took more than 6 hours to finish, you need faster hardware or more threads"
    print "INFO: in sequential style discovery the elapsed time would have been: %s seconds" % real_duration
    for device in per_device_duration:
        if per_device_duration[device] > 3600:
            print "WARNING: device %s is taking too long: %s seconds" % (device, per_device_duration[device])
            show_stopper = True
    if show_stopper:
        print "ERROR: Some devices are taking more than 3600 seconds, the script cannot recommend you what to do."
    else:
        recommend = int(total_time / 300.0 * amount_of_workers + 1)
        print "WARNING: Consider setting a minimum of %d threads. (This does not constitute professional advice!)" % recommend

    sys.exit(2)
