#!/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

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


def add_lease(mac, ip_address):
    """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(),
                                       ip_address)
    else:
        rpc.cast(context.get_admin_context(),
                 "%s.%s" % (FLAGS.network_topic, FLAGS.host),
                 {"method": "lease_fixed_ip",
                  "args": {"address": ip_address}})


def old_lease(mac, ip_address):
    """Called when an old lease is recognized."""
    # NOTE(vish): We assume we heard about this lease the first time.
    #             If not, we will get it the next time the lease is
    #             renewed.
    pass


def del_lease(mac, ip_address):
    """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(),
                                         ip_address)
    else:
        rpc.cast(context.get_admin_context(),
                 "%s.%s" % (FLAGS.network_topic, FLAGS.host),
                 {"method": "release_fixed_ip",
                  "args": {"address": ip_address}})


def init_leases(network_id):
    """Get the list of hosts for a network."""
    ctxt = context.get_admin_context()
    network_ref = db.network_get(ctxt, network_id)
    network_manager = utils.import_object(FLAGS.network_manager)
    return network_manager.get_dhcp_leases(ctxt, network_ref)


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()

    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]
        msg = _("Called '%(action)s' for mac '%(mac)s' with ip '%(ip)s'") % \
                    {"action": action,
                     "mac": mac,
                     "ip": ip}
        LOG.debug(msg)
        globals()[action + '_lease'](mac, ip)
    else:
        try:
            network_id = int(os.environ.get('NETWORK_ID'))
        except TypeError:
            LOG.error(_("Environment variable 'NETWORK_ID' must be set."))
            sys.exit(1)

        print init_leases(network_id)

    rpc.cleanup()


if __name__ == "__main__":
    main()