#!/usr/bin/env python
#
# Copyright (c) 2014 Marin Atanasov Nikolov <dnaeon@gmail.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
#    in this position and unchanged.
# 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(S) ``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.
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"""
vevents-cli is an application used for monitoring
events of a VMware vSphere server from the command-line.

"""

import logging
import pyVmomi

from time import sleep
from docopt import docopt
from vconnector.core import VConnector
from vconnector.core import VConnectorDatabase

def monitor_vsphere_events(agent, interval):
    """
    Continuously monitors the VMware vSphere Events

    For monitoring of VMware vSphere Events we use an EventHistoryCollector
    and monitor for any new events in the collector.

    For more information about EventHistoryCollector,
    please refer to this chapter of the VMware vSphere API documentation:
    
        - http://pubs.vmware.com/vsphere-55/index.jsp#com.vmware.wssdk.pg.doc/PG_Alarms.17.1.html

    Args:
        host     (tuple): Connection details of the vSphere host we connect to
        interval (float): Check for new events every 'interval' seconds
    
    """
    client = VConnector(
        user=agent['user'],
        pwd=agent['pwd'],
        host=agent['host']
    )
    client.connect()

    # Create an Event filter spec and a collector for our Events
    logging.info('Getting Event Collector')
    filter_spec = pyVmomi.vim.event.EventFilterSpec()
    collector   = client.si.content.eventManager.CreateCollectorForEvents(filter=filter_spec)

    logging.info('Retrieving Events from vSphere host %s', agent['host'])
    last_event_key = None
    try:
        while True:
            # New events will be inserted at the first element in the collector.latestPage list
            event = collector.latestPage[0]

            if last_event_key != event.key:
                print '[%s] %s' % (event.createdTime, event.fullFormattedMessage)
                last_event_key = event.key

            sleep(float(interval))
    except KeyboardInterrupt:
        print '\nCaught keyboard interrupt, exiting ...'

    collector.DestroyCollector()
    client.disconnect()

def get_vsphere_agent(db, host):
    """
    Get the connection details for a vSphere Agent from the database

    Args:
        db   (str): Path to the vConnector database file
        host (str): Hostname of the vSphere host from the database

    Returns:
        The connection details for the vSphere host if found, None otherwise

    """
    db = VConnectorDatabase(db)
    agents = db.get_agents(only_enabled=True)

    for agent in agents:
        if agent['host'] == host:
            break
    else:
        return None

    return agent

def main():
    usage="""
Usage: vevents-cli [-D] [-d <db>] [-i <interval>] -H <host>
       vevents-cli (-h|-v)

Options:
  -h, --help                            Display this usage info
  -v, --version                         Display version and exit
  -D, --debug                           Run in debug mode, be more verbose
  -d <db>, --database <db>              Path to the vConnector SQLite database file
                                        [default: /var/lib/vconnector/vconnector.db]
  -i <interval>, --interval <interval>  Check for new events every 'interval' seconds
                                        [default: 1.0]
  -H <host>, --host <host>              Specify the vSphere hostname to connect to

"""

    args = docopt(usage, version="0.1.0")

    level = logging.DEBUG if args['--debug'] else logging.INFO
    logging.basicConfig(
        format='%(asctime)s - %(levelname)s - vevents-cli[%(process)s]: %(message)s',
        level=level
    )

    agent = get_vsphere_agent(
        db=args['--database'],
        host=args['--host']
    )

    if not agent:
        raise SystemExit, 'vSphere Agent %s is not registered or is disabled' % args['--host']

    monitor_vsphere_events(agent=agent, interval=args['--interval'])

if __name__ == '__main__':
    main()

