#!/usr/bin/env python
# vim: tabstop=4 shiftwidth=4 softtabstop=4

# Copyright 2010 United States Government as represented by the
# Administrator of the National Aeronautics and Space Administration.
# All Rights Reserved.
#
#    Licensed under the Apache License, Version 2.0 (the "License"); you may
#    not use this file except in compliance with the License. You may obtain
#    a copy of the License at
#
#         http://www.apache.org/licenses/LICENSE-2.0
#
#    Unless required by applicable law or agreed to in writing, software
#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
#    License for the specific language governing permissions and limitations
#    under the License.

"""
Handle lease database updates from DHCP servers.
"""

import gettext
import os
import sys

# If ../nova/__init__.py exists, add ../ to Python search path, so that
# it will override what happens to be installed in /usr/(local/)lib/python...
possible_topdir = os.path.normpath(os.path.join(os.path.abspath(sys.argv[0]),
                                   os.pardir,
                                   os.pardir))
if os.path.exists(os.path.join(possible_topdir, 'nova', '__init__.py')):
    sys.path.insert(0, possible_topdir)

gettext.install('nova', unicode=1)

from nova import context
from nova import db
from nova import flags
from nova import log as logging
from nova import rpc
from nova import utils
from nova.network import linux_net

FLAGS = flags.FLAGS
flags.DECLARE('auth_driver', 'nova.auth.manager')
flags.DECLARE('network_size', 'nova.network.manager')
flags.DECLARE('num_networks', 'nova.network.manager')
flags.DECLARE('update_dhcp_on_disassociate', 'nova.network.manager')

LOG = logging.getLogger('nova.dhcpbridge')


def add_lease(mac, ip_address, _hostname, _interface):
    """Set the IP that was assigned by the DHCP server."""
    if FLAGS.fake_rabbit:
        LOG.debug(_("leasing ip"))
        network_manager = utils.import_object(FLAGS.network_manager)
        network_manager.lease_fixed_ip(context.get_admin_context(),
                                       mac,
                                       ip_address)
    else:
        rpc.cast(context.get_admin_context(),
                 "%s.%s" % (FLAGS.network_topic, FLAGS.host),
                 {"method": "lease_fixed_ip",
                  "args": {"mac": mac,
                           "address": ip_address}})


def old_lease(mac, ip_address, hostname, interface):
    """Update just as add lease."""
    LOG.debug(_("Adopted old lease or got a change of mac/hostname"))
    add_lease(mac, ip_address, hostname, interface)


def del_lease(mac, ip_address, _hostname, _interface):
    """Called when a lease expires."""
    if FLAGS.fake_rabbit:
        LOG.debug(_("releasing ip"))
        network_manager = utils.import_object(FLAGS.network_manager)
        network_manager.release_fixed_ip(context.get_admin_context(),
                                         mac,
                                         ip_address)
    else:
        rpc.cast(context.get_admin_context(),
                 "%s.%s" % (FLAGS.network_topic, FLAGS.host),
                 {"method": "release_fixed_ip",
                  "args": {"mac": mac,
                           "address": ip_address}})


def init_leases(interface):
    """Get the list of hosts for an interface."""
    ctxt = context.get_admin_context()
    network_ref = db.network_get_by_bridge(ctxt, interface)
    return linux_net.get_dhcp_leases(ctxt, network_ref['id'])


def main():
    """Parse environment and arguments and call the approproate action."""
    flagfile = os.environ.get('FLAGFILE', FLAGS.dhcpbridge_flagfile)
    utils.default_flagfile(flagfile)
    argv = FLAGS(sys.argv)
    logging.setup()
    interface = os.environ.get('DNSMASQ_INTERFACE', 'br0')
    if int(os.environ.get('TESTING', '0')):
        from nova.tests import fake_flags
    action = argv[1]
    if action in ['add', 'del', 'old']:
        mac = argv[2]
        ip = argv[3]
        hostname = argv[4]
        msg = _("Called %(action)s for mac %(mac)s with ip %(ip)s and"
                " hostname %(hostname)s on interface %(interface)s") % locals()
        LOG.debug(msg)
        globals()[action + '_lease'](mac, ip, hostname, interface)
    else:
        print init_leases(interface)

if __name__ == "__main__":
    main()