# Copyright 2012 OpenStack Foundation
# All Rights Reserved
# Copyright (c) 2012 NEC Corporation
#
#    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.
#

import time

from neutronclient.common import exceptions as neutron_client_exc
from oslo.config import cfg

from nova.compute import flavors
from nova.compute import utils as compute_utils
from nova import conductor
from nova.db import base
from nova import exception
from nova.network import api as network_api
from nova.network import model as network_model
from nova.network import neutronv2
from nova.network.neutronv2 import constants
from nova.network.security_group import openstack_driver
from nova.openstack.common import excutils
from nova.openstack.common.gettextutils import _
from nova.openstack.common import lockutils
from nova.openstack.common import log as logging
from nova.openstack.common import uuidutils

neutron_opts = [
    cfg.StrOpt('neutron_url',
               default='http://127.0.0.1:9696',
               help='URL for connecting to neutron'),
    cfg.IntOpt('neutron_url_timeout',
               default=30,
               help='Timeout value for connecting to neutron in seconds'),
    cfg.StrOpt('neutron_admin_username',
               help='Username for connecting to neutron in admin context'),
    cfg.StrOpt('neutron_admin_password',
               help='Password for connecting to neutron in admin context',
               secret=True),
    cfg.StrOpt('neutron_admin_tenant_id',
               help='Tenant id for connecting to neutron in admin context'),
    cfg.StrOpt('neutron_admin_tenant_name',
               help='Tenant name for connecting to neutron in admin context. '
                    'This option is mutually exclusive with '
                    'neutron_admin_tenant_id. Note that with Keystone V3 '
                    'tenant names are only unique within a domain.'),
    cfg.StrOpt('neutron_region_name',
               help='Region name for connecting to neutron in admin context'),
    cfg.StrOpt('neutron_admin_auth_url',
               default='http://localhost:5000/v2.0',
               help='Authorization URL for connecting to neutron in admin '
               'context'),
    cfg.BoolOpt('neutron_api_insecure',
                default=False,
                help='If set, ignore any SSL validation issues'),
    cfg.StrOpt('neutron_auth_strategy',
               default='keystone',
               help='Authorization strategy for connecting to '
                    'neutron in admin context'),
    # TODO(berrange) temporary hack until Neutron can pass over the
    # name of the OVS bridge it is configured with
    cfg.StrOpt('neutron_ovs_bridge',
               default='br-int',
               help='Name of Integration Bridge used by Open vSwitch'),
    cfg.IntOpt('neutron_extension_sync_interval',
                default=600,
                help='Number of seconds before querying neutron for'
                     ' extensions'),
    cfg.StrOpt('neutron_ca_certificates_file',
                help='Location of CA certificates file to use for '
                     'neutron client requests.'),
   ]

CONF = cfg.CONF
CONF.register_opts(neutron_opts)
CONF.import_opt('default_floating_pool', 'nova.network.floating_ips')
CONF.import_opt('flat_injected', 'nova.network.manager')
LOG = logging.getLogger(__name__)

refresh_cache = network_api.refresh_cache
update_instance_info_cache = network_api.update_instance_cache_with_nw_info


class API(base.Base):
    """API for interacting with the neutron 2.x API."""
    _sentinel = object()

    def __init__(self):
        super(API, self).__init__()
        self.last_neutron_extension_sync = None
        self.extensions = {}
        self.conductor_api = conductor.API()
        self.security_group_api = (
            openstack_driver.get_openstack_security_group_driver())

    def setup_networks_on_host(self, context, instance, host=None,
                               teardown=False):
        """Setup or teardown the network structures."""

    def _get_available_networks(self, context, project_id,
                                net_ids=None, neutron=None):
        """Return a network list available for the tenant.
        The list contains networks owned by the tenant and public networks.
        If net_ids specified, it searches networks with requested IDs only.
        """
        if not neutron:
            neutron = neutronv2.get_client(context)

        if net_ids:
            # If user has specified to attach instance only to specific
            # networks then only add these to **search_opts. This search will
            # also include 'shared' networks.
            search_opts = {'id': net_ids}
            nets = neutron.list_networks(**search_opts).get('networks', [])
        else:
            # (1) Retrieve non-public network list owned by the tenant.
            search_opts = {'tenant_id': project_id, 'shared': False}
            nets = neutron.list_networks(**search_opts).get('networks', [])
            # (2) Retrieve public network list.
            search_opts = {'shared': True}
            nets += neutron.list_networks(**search_opts).get('networks', [])

        _ensure_requested_network_ordering(
            lambda x: x['id'],
            nets,
            net_ids)

        if not context.is_admin:
            for net in nets:
                # Perform this check here rather than in validate_networks to
                # ensure the check is performed everytime allocate_for_instance
                # is invoked
                if net.get('router:external'):
                    raise exception.ExternalNetworkAttachForbidden(
                        network_uuid=net['id'])

        return nets

    def _create_port(self, port_client, instance, network_id, port_req_body,
                     fixed_ip=None, security_group_ids=None,
                     available_macs=None, dhcp_opts=None):
        """Attempts to create a port for the instance on the given network.

        :param port_client: The client to use to create the port.
        :param instance: Create the port for the given instance.
        :param network_id: Create the port on the given network.
        :param port_req_body: Pre-populated port request. Should have the
            device_id, device_owner, and any required neutron extension values.
        :param fixed_ip: Optional fixed IP to use from the given network.
        :param security_group_ids: Optional list of security group IDs to
            apply to the port.
        :param available_macs: Optional set of available MAC addresses to use.
        :param dhcp_opts: Optional DHCP options.
        :returns: ID of the created port.
        :raises PortLimitExceeded: If neutron fails with an OverQuota error.
        """
        try:
            if fixed_ip:
                port_req_body['port']['fixed_ips'] = [{'ip_address': fixed_ip}]
            port_req_body['port']['network_id'] = network_id
            port_req_body['port']['admin_state_up'] = True
            port_req_body['port']['tenant_id'] = instance['project_id']
            if security_group_ids:
                port_req_body['port']['security_groups'] = security_group_ids
            if available_macs is not None:
                if not available_macs:
                    raise exception.PortNotFree(
                        instance=instance['display_name'])
                mac_address = available_macs.pop()
                port_req_body['port']['mac_address'] = mac_address
            if dhcp_opts is not None:
                port_req_body['port']['extra_dhcp_opts'] = dhcp_opts
            port_id = port_client.create_port(port_req_body)['port']['id']
            LOG.debug(_('Successfully created port: %s') % port_id,
                      instance=instance)
            return port_id
        except neutron_client_exc.NeutronClientException as e:
            # NOTE(mriedem): OverQuota in neutron is a 409
            if e.status_code == 409:
                LOG.warning(_('Neutron error: quota exceeded'))
                raise exception.PortLimitExceeded()
            with excutils.save_and_reraise_exception():
                LOG.exception(_('Neutron error creating port on network %s'),
                              network_id, instance=instance)

    def allocate_for_instance(self, context, instance, **kwargs):
        """Allocate network resources for the instance.

        :param requested_networks: optional value containing
            network_id, fixed_ip, and port_id
        :param security_groups: security groups to allocate for instance
        :param macs: None or a set of MAC addresses that the instance
            should use. macs is supplied by the hypervisor driver (contrast
            with requested_networks which is user supplied).
            NB: NeutronV2 currently assigns hypervisor supplied MAC addresses
            to arbitrary networks, which requires openflow switches to
            function correctly if more than one network is being used with
            the bare metal hypervisor (which is the only one known to limit
            MAC addresses).
        :param dhcp_options: None or a set of key/value pairs that should
            determine the DHCP BOOTP response, eg. for PXE booting an instance
            configured with the baremetal hypervisor. It is expected that these
            are already formatted for the neutron v2 api.
            See nova/virt/driver.py:dhcp_options_for_instance for an example.
        """
        hypervisor_macs = kwargs.get('macs', None)
        available_macs = None
        if hypervisor_macs is not None:
            # Make a copy we can mutate: records macs that have not been used
            # to create a port on a network. If we find a mac with a
            # pre-allocated port we also remove it from this set.
            available_macs = set(hypervisor_macs)
        neutron = neutronv2.get_client(context)
        LOG.debug(_('allocate_for_instance() for %s'),
                  instance['display_name'])
        if not instance['project_id']:
            msg = _('empty project id for instance %s')
            raise exception.InvalidInput(
                reason=msg % instance['display_name'])
        requested_networks = kwargs.get('requested_networks')
        dhcp_opts = kwargs.get('dhcp_options', None)
        ports = {}
        fixed_ips = {}
        net_ids = []
        if requested_networks:
            for network_id, fixed_ip, port_id in requested_networks:
                if port_id:
                    port = neutron.show_port(port_id)['port']
                    if port.get('device_id'):
                        raise exception.PortInUse(port_id=port_id)
                    if hypervisor_macs is not None:
                        if port['mac_address'] not in hypervisor_macs:
                            raise exception.PortNotUsable(port_id=port_id,
                                instance=instance['display_name'])
                        else:
                            # Don't try to use this MAC if we need to create a
                            # port on the fly later. Identical MACs may be
                            # configured by users into multiple ports so we
                            # discard rather than popping.
                            available_macs.discard(port['mac_address'])
                    network_id = port['network_id']
                    ports[network_id] = port
                elif fixed_ip and network_id:
                    fixed_ips[network_id] = fixed_ip
                if network_id:
                    net_ids.append(network_id)

        nets = self._get_available_networks(context, instance['project_id'],
                                            net_ids)

        if not nets:
            LOG.warn(_("No network configured!"), instance=instance)
            return network_model.NetworkInfo([])

        security_groups = kwargs.get('security_groups', [])
        security_group_ids = []

        # TODO(arosen) Should optimize more to do direct query for security
        # group if len(security_groups) == 1
        if len(security_groups):
            search_opts = {'tenant_id': instance['project_id']}
            user_security_groups = neutron.list_security_groups(
                **search_opts).get('security_groups')

        for security_group in security_groups:
            name_match = None
            uuid_match = None
            for user_security_group in user_security_groups:
                if user_security_group['name'] == security_group:
                    if name_match:
                        raise exception.NoUniqueMatch(
                            _("Multiple security groups found matching"
                              " '%s'. Use an ID to be more specific.") %
                               security_group)

                    name_match = user_security_group['id']
                if user_security_group['id'] == security_group:
                    uuid_match = user_security_group['id']

            # If a user names the security group the same as
            # another's security groups uuid, the name takes priority.
            if not name_match and not uuid_match:
                raise exception.SecurityGroupNotFound(
                    security_group_id=security_group)
            elif name_match:
                security_group_ids.append(name_match)
            elif uuid_match:
                security_group_ids.append(uuid_match)

        touched_port_ids = []
        created_port_ids = []
        ports_in_requested_order = []
        for network in nets:
            # If security groups are requested on an instance then the
            # network must has a subnet associated with it. Some plugins
            # implement the port-security extension which requires
            # 'port_security_enabled' to be True for security groups.
            # That is why True is returned if 'port_security_enabled'
            # is not found.
            if (security_groups and not (
                    network['subnets']
                    and network.get('port_security_enabled', True))):

                raise exception.SecurityGroupCannotBeApplied()
            network_id = network['id']
            zone = 'compute:%s' % instance['availability_zone']
            port_req_body = {'port': {'device_id': instance['uuid'],
                                      'device_owner': zone}}
            try:
                port = ports.get(network_id)
                self._populate_neutron_extension_values(context, instance,
                                                        port_req_body)
                # Requires admin creds to set port bindings
                port_client = (neutron if not
                               self._has_port_binding_extension(context) else
                               neutronv2.get_client(context, admin=True))
                if port:
                    port_client.update_port(port['id'], port_req_body)
                    touched_port_ids.append(port['id'])
                    ports_in_requested_order.append(port['id'])
                else:
                    created_port = self._create_port(
                            port_client, instance, network_id,
                            port_req_body, fixed_ips.get(network_id),
                            security_group_ids, available_macs, dhcp_opts)
                    created_port_ids.append(created_port)
                    ports_in_requested_order.append(created_port)
            except Exception:
                with excutils.save_and_reraise_exception():
                    for port_id in touched_port_ids:
                        try:
                            port_req_body = {'port': {'device_id': None}}
                            # Requires admin creds to set port bindings
                            if self._has_port_binding_extension(context):
                                port_req_body['port']['binding:host_id'] = None
                                port_client = neutronv2.get_client(
                                    context, admin=True)
                            else:
                                port_client = neutron
                            port_client.update_port(port_id, port_req_body)
                        except Exception:
                            msg = _("Failed to update port %s")
                            LOG.exception(msg, port_id)

                    for port_id in created_port_ids:
                        try:
                            neutron.delete_port(port_id)
                        except Exception:
                            msg = _("Failed to delete port %s")
                            LOG.exception(msg, port_id)

        nw_info = self.get_instance_nw_info(context, instance, networks=nets,
                                            port_ids=ports_in_requested_order)
        # NOTE(danms): Only return info about ports we created in this run.
        # In the initial allocation case, this will be everything we created,
        # and in later runs will only be what was created that time. Thus,
        # this only affects the attach case, not the original use for this
        # method.
        return network_model.NetworkInfo([port for port in nw_info
                                          if port['id'] in created_port_ids +
                                                           touched_port_ids])

    def _refresh_neutron_extensions_cache(self, context):
        """Refresh the neutron extensions cache when necessary."""
        if (not self.last_neutron_extension_sync or
            ((time.time() - self.last_neutron_extension_sync)
             >= CONF.neutron_extension_sync_interval)):
            neutron = neutronv2.get_client(context)
            extensions_list = neutron.list_extensions()['extensions']
            self.last_neutron_extension_sync = time.time()
            self.extensions.clear()
            self.extensions = dict((ext['name'], ext)
                                   for ext in extensions_list)

    def _has_port_binding_extension(self, context, refresh_cache=False):
        if refresh_cache:
            self._refresh_neutron_extensions_cache(context)
        return constants.PORTBINDING_EXT in self.extensions

    def _populate_neutron_extension_values(self, context, instance,
                                           port_req_body):
        """Populate neutron extension values for the instance.

        If the extension contains nvp-qos then get the rxtx_factor.
        """
        self._refresh_neutron_extensions_cache(context)
        if 'nvp-qos' in self.extensions:
            flavor = flavors.extract_flavor(instance)
            rxtx_factor = flavor.get('rxtx_factor')
            port_req_body['port']['rxtx_factor'] = rxtx_factor
        if self._has_port_binding_extension(context):
            port_req_body['port']['binding:host_id'] = instance.get('host')

    def deallocate_for_instance(self, context, instance, **kwargs):
        """Deallocate all network resources related to the instance."""
        LOG.debug(_('deallocate_for_instance() for %s'),
                  instance['display_name'])
        search_opts = {'device_id': instance['uuid']}
        neutron = neutronv2.get_client(context)
        data = neutron.list_ports(**search_opts)
        ports = [port['id'] for port in data.get('ports', [])]

        requested_networks = kwargs.get('requested_networks') or {}
        ports_to_skip = [port_id for nets, fips, port_id in requested_networks]
        ports = set(ports) - set(ports_to_skip)
        # Reset device_id and device_owner for the ports that are skipped
        for port in ports_to_skip:
            port_req_body = {'port': {'device_id': '', 'device_owner': ''}}
            try:
                neutronv2.get_client(context).update_port(port,
                                                          port_req_body)
            except Exception:
                LOG.info(_('Unable to reset device ID for port %s'), port,
                         instance=instance)

        for port in ports:
            try:
                neutron.delete_port(port)
            except neutronv2.exceptions.NeutronClientException as e:
                if e.status_code == 404:
                    LOG.warning(_("Port %s does not exist"), port)
                else:
                    with excutils.save_and_reraise_exception():
                        LOG.exception(_("Failed to delete neutron port %s"),
                                      port)

        # NOTE(arosen): This clears out the network_cache only if the instance
        # hasn't already been deleted. This is needed when an instance fails to
        # launch and is rescheduled onto another compute node. If the instance
        # has already been deleted this call does nothing.
        update_instance_info_cache(self, context, instance,
                                   network_model.NetworkInfo([]))

    def allocate_port_for_instance(self, context, instance, port_id,
                                   network_id=None, requested_ip=None):
        """Allocate a port for the instance."""
        return self.allocate_for_instance(context, instance,
                requested_networks=[(network_id, requested_ip, port_id)])

    def deallocate_port_for_instance(self, context, instance, port_id):
        """Remove a specified port from the instance.

        Return network information for the instance
        """
        try:
            neutronv2.get_client(context).delete_port(port_id)
        except Exception:
            LOG.exception(_("Failed to delete neutron port %s") %
                          port_id)

        return self.get_instance_nw_info(context, instance)

    def list_ports(self, context, **search_opts):
        """List ports for the client based on search options."""
        return neutronv2.get_client(context).list_ports(**search_opts)

    def show_port(self, context, port_id):
        """Return the port for the client given the port id."""
        return neutronv2.get_client(context).show_port(port_id)

    def get_instance_nw_info(self, context, instance, networks=None,
                             port_ids=None, use_slave=False):
        """Return network information for specified instance
           and update cache.
        """
        # NOTE(geekinutah): It would be nice if use_slave had us call
        #                   special APIs that pummeled slaves instead of
        #                   the master. For now we just ignore this arg.
        with lockutils.lock('refresh_cache-%s' % instance['uuid']):
            result = self._get_instance_nw_info(context, instance, networks,
                                                port_ids)
            update_instance_info_cache(self, context,
                                       instance,
                                       nw_info=result,
                                       update_cells=False)
        return result

    def _get_instance_nw_info(self, context, instance, networks=None,
                              port_ids=None):
        # NOTE(danms): This is an inner method intended to be called
        # by other code that updates instance nwinfo. It *must* be
        # called with the refresh_cache-%(instance_uuid) lock held!
        LOG.debug(_('get_instance_nw_info() for %s'), instance['display_name'])
        nw_info = self._build_network_info_model(context, instance, networks,
                                                 port_ids)
        return network_model.NetworkInfo.hydrate(nw_info)

    def _gather_port_ids_and_networks(self, context, instance, networks=None,
                                      port_ids=None):
        """Return an instance's complete list of port_ids and networks."""

        if ((networks is None and port_ids is not None) or
            (port_ids is None and networks is not None)):
            message = ("This method needs to be called with either "
                       "networks=None and port_ids=None or port_ids and "
                       " networks as not none.")
            raise exception.NovaException(message=message)

        ifaces = compute_utils.get_nw_info_for_instance(instance)
        # This code path is only done when refreshing the network_cache
        if port_ids is None:
            port_ids = [iface['id'] for iface in ifaces]
            net_ids = [iface['network']['id'] for iface in ifaces]

        if networks is None:
            networks = self._get_available_networks(context,
                                                    instance['project_id'],
                                                    net_ids)
        # an interface was added/removed from instance.
        else:
            # Since networks does not contain the existing networks on the
            # instance we use their values from the cache and add it.
            networks = networks + [
                {'id': iface['network']['id'],
                 'name': iface['network']['label'],
                 'tenant_id': iface['network']['meta']['tenant_id']}
                for iface in ifaces]

            # Include existing interfaces so they are not removed from the db.
            port_ids = [iface['id'] for iface in ifaces] + port_ids

        return networks, port_ids

    @refresh_cache
    def add_fixed_ip_to_instance(self, context, instance, network_id):
        """Add a fixed ip to the instance from specified network."""
        search_opts = {'network_id': network_id}
        data = neutronv2.get_client(context).list_subnets(**search_opts)
        ipam_subnets = data.get('subnets', [])
        if not ipam_subnets:
            raise exception.NetworkNotFoundForInstance(
                instance_id=instance['uuid'])

        zone = 'compute:%s' % instance['availability_zone']
        search_opts = {'device_id': instance['uuid'],
                       'device_owner': zone,
                       'network_id': network_id}
        data = neutronv2.get_client(context).list_ports(**search_opts)
        ports = data['ports']
        for p in ports:
            for subnet in ipam_subnets:
                fixed_ips = p['fixed_ips']
                fixed_ips.append({'subnet_id': subnet['id']})
                port_req_body = {'port': {'fixed_ips': fixed_ips}}
                try:
                    neutronv2.get_client(context).update_port(p['id'],
                                                              port_req_body)
                    return
                except Exception as ex:
                    msg = _("Unable to update port %(portid)s on subnet "
                            "%(subnet_id)s with failure: %(exception)s")
                    LOG.debug(msg, {'portid': p['id'],
                                    'subnet_id': subnet['id'],
                                    'exception': ex})

        raise exception.NetworkNotFoundForInstance(
                instance_id=instance['uuid'])

    @refresh_cache
    def remove_fixed_ip_from_instance(self, context, instance, address):
        """Remove a fixed ip from the instance."""
        zone = 'compute:%s' % instance['availability_zone']
        search_opts = {'device_id': instance['uuid'],
                       'device_owner': zone,
                       'fixed_ips': 'ip_address=%s' % address}
        data = neutronv2.get_client(context).list_ports(**search_opts)
        ports = data['ports']
        for p in ports:
            fixed_ips = p['fixed_ips']
            new_fixed_ips = []
            for fixed_ip in fixed_ips:
                if fixed_ip['ip_address'] != address:
                    new_fixed_ips.append(fixed_ip)
            port_req_body = {'port': {'fixed_ips': new_fixed_ips}}
            try:
                neutronv2.get_client(context).update_port(p['id'],
                                                          port_req_body)
            except Exception as ex:
                msg = _("Unable to update port %(portid)s with"
                        " failure: %(exception)s")
                LOG.debug(msg, {'portid': p['id'], 'exception': ex})
            return

        raise exception.FixedIpNotFoundForSpecificInstance(
                instance_uuid=instance['uuid'], ip=address)

    def validate_networks(self, context, requested_networks, num_instances):
        """Validate that the tenant can use the requested networks.

        Return the number of instances than can be successfully allocated
        with the requested network configuration.
        """
        LOG.debug(_('validate_networks() for %s'),
                  requested_networks)

        neutron = neutronv2.get_client(context)
        ports_needed_per_instance = 0

        if not requested_networks:
            nets = self._get_available_networks(context, context.project_id,
                                                neutron=neutron)
            if len(nets) > 1:
                # Attaching to more than one network by default doesn't
                # make sense, as the order will be arbitrary and the guest OS
                # won't know which to configure
                msg = _("Multiple possible networks found, use a Network "
                         "ID to be more specific.")
                raise exception.NetworkAmbiguous(msg)
            else:
                ports_needed_per_instance = 1

        else:
            net_ids = []

            for (net_id, _i, port_id) in requested_networks:
                if port_id:
                    try:
                        port = neutron.show_port(port_id).get('port')
                    except neutronv2.exceptions.NeutronClientException as e:
                        if e.status_code == 404:
                            port = None
                        else:
                            with excutils.save_and_reraise_exception():
                                LOG.exception(_("Failed to access port %s"),
                                              port_id)
                    if not port:
                        raise exception.PortNotFound(port_id=port_id)
                    if port.get('device_id', None):
                        raise exception.PortInUse(port_id=port_id)
                    if not port.get('fixed_ips'):
                        raise exception.PortRequiresFixedIP(port_id=port_id)
                    net_id = port['network_id']
                else:
                    ports_needed_per_instance += 1

                if net_id in net_ids:
                    raise exception.NetworkDuplicated(network_id=net_id)
                net_ids.append(net_id)

            # Now check to see if all requested networks exist
            nets = self._get_available_networks(context,
                                    context.project_id, net_ids,
                                    neutron=neutron)
            for net in nets:
                if not net.get('subnets'):
                    raise exception.NetworkRequiresSubnet(
                        network_uuid=net['id'])

            if len(nets) != len(net_ids):
                requsted_netid_set = set(net_ids)
                returned_netid_set = set([net['id'] for net in nets])
                lostid_set = requsted_netid_set - returned_netid_set
                id_str = ''
                for _id in lostid_set:
                    id_str = id_str and id_str + ', ' + _id or _id
                raise exception.NetworkNotFound(network_id=id_str)

        # Note(PhilD): Ideally Nova would create all required ports as part of
        # network validation, but port creation requires some details
        # from the hypervisor.  So we just check the quota and return
        # how many of the requested number of instances can be created

        ports = neutron.list_ports(tenant_id=context.project_id)['ports']
        quotas = neutron.show_quota(tenant_id=context.project_id)['quota']
        if quotas.get('port', -1) == -1:
            # Unlimited Port Quota
            return num_instances
        else:
            free_ports = quotas.get('port') - len(ports)
            ports_needed = ports_needed_per_instance * num_instances
            if free_ports >= ports_needed:
                return num_instances
            else:
                return free_ports // ports_needed_per_instance

    def _get_instance_uuids_by_ip(self, context, address):
        """Retrieve instance uuids associated with the given ip address.

        :returns: A list of dicts containing the uuids keyed by 'instance_uuid'
                  e.g. [{'instance_uuid': uuid}, ...]
        """
        search_opts = {"fixed_ips": 'ip_address=%s' % address}
        data = neutronv2.get_client(context).list_ports(**search_opts)
        ports = data.get('ports', [])
        return [{'instance_uuid': port['device_id']} for port in ports
                if port['device_id']]

    def get_instance_uuids_by_ip_filter(self, context, filters):
        """Return a list of dicts in the form of
        [{'instance_uuid': uuid}] that matched the ip filter.
        """
        # filters['ip'] is composed as '^%s$' % fixed_ip.replace('.', '\\.')
        ip = filters.get('ip')
        # we remove ^$\ in the ip filer
        if ip[0] == '^':
            ip = ip[1:]
        if ip[-1] == '$':
            ip = ip[:-1]
        ip = ip.replace('\\.', '.')
        return self._get_instance_uuids_by_ip(context, ip)

    def _get_port_id_by_fixed_address(self, client,
                                      instance, address):
        """Return port_id from a fixed address."""
        zone = 'compute:%s' % instance['availability_zone']
        search_opts = {'device_id': instance['uuid'],
                       'device_owner': zone}
        data = client.list_ports(**search_opts)
        ports = data['ports']
        port_id = None
        for p in ports:
            for ip in p['fixed_ips']:
                if ip['ip_address'] == address:
                    port_id = p['id']
                    break
        if not port_id:
            raise exception.FixedIpNotFoundForAddress(address=address)
        return port_id

    @refresh_cache
    def associate_floating_ip(self, context, instance,
                              floating_address, fixed_address,
                              affect_auto_assigned=False):
        """Associate a floating ip with a fixed ip."""

        # Note(amotoki): 'affect_auto_assigned' is not respected
        # since it is not used anywhere in nova code and I could
        # find why this parameter exists.

        client = neutronv2.get_client(context)
        port_id = self._get_port_id_by_fixed_address(client, instance,
                                                     fixed_address)
        fip = self._get_floating_ip_by_address(client, floating_address)
        param = {'port_id': port_id,
                 'fixed_ip_address': fixed_address}
        client.update_floatingip(fip['id'], {'floatingip': param})

        if fip['port_id']:
            port = client.show_port(fip['port_id'])['port']
            orig_instance_uuid = port['device_id']

            msg_dict = dict(address=floating_address,
                            instance_id=orig_instance_uuid)
            LOG.info(_('re-assign floating IP %(address)s from '
                       'instance %(instance_id)s') % msg_dict)
            orig_instance = self.db.instance_get_by_uuid(context,
                                                         orig_instance_uuid)

            # purge cached nw info for the original instance
            update_instance_info_cache(self, context, orig_instance)

    def get_all(self, context):
        """Get all networks for client."""
        client = neutronv2.get_client(context)
        networks = client.list_networks().get('networks')
        for network in networks:
            network['label'] = network['name']
        return networks

    def get(self, context, network_uuid):
        """Get specific network for client."""
        client = neutronv2.get_client(context)
        network = client.show_network(network_uuid).get('network') or {}
        network['label'] = network['name']
        return network

    def delete(self, context, network_uuid):
        """Delete a network for client."""
        raise NotImplementedError()

    def disassociate(self, context, network_uuid):
        """Disassociate a network for client."""
        raise NotImplementedError()

    def associate(self, context, network_uuid, host=_sentinel,
                  project=_sentinel):
        """Associate a network for client."""
        raise NotImplementedError()

    def get_fixed_ip(self, context, id):
        """Get a fixed ip from the id."""
        raise NotImplementedError()

    def get_fixed_ip_by_address(self, context, address):
        """Return instance uuids given an address."""
        uuid_maps = self._get_instance_uuids_by_ip(context, address)
        if len(uuid_maps) == 1:
            return uuid_maps[0]
        elif not uuid_maps:
            raise exception.FixedIpNotFoundForAddress(address=address)
        else:
            raise exception.FixedIpAssociatedWithMultipleInstances(
                address=address)

    def _setup_net_dict(self, client, network_id):
        if not network_id:
            return {}
        pool = client.show_network(network_id)['network']
        return {pool['id']: pool}

    def _setup_port_dict(self, client, port_id):
        if not port_id:
            return {}
        port = client.show_port(port_id)['port']
        return {port['id']: port}

    def _setup_pools_dict(self, client):
        pools = self._get_floating_ip_pools(client)
        return dict([(i['id'], i) for i in pools])

    def _setup_ports_dict(self, client, project_id=None):
        search_opts = {'tenant_id': project_id} if project_id else {}
        ports = client.list_ports(**search_opts)['ports']
        return dict([(p['id'], p) for p in ports])

    def get_floating_ip(self, context, id):
        """Return floating ip object given the floating ip id."""
        client = neutronv2.get_client(context)
        try:
            fip = client.show_floatingip(id)['floatingip']
        except neutronv2.exceptions.NeutronClientException as e:
            if e.status_code == 404:
                raise exception.FloatingIpNotFound(id=id)
            else:
                with excutils.save_and_reraise_exception():
                    LOG.exception(_('Unable to access floating IP %s'), id)
        pool_dict = self._setup_net_dict(client,
                                         fip['floating_network_id'])
        port_dict = self._setup_port_dict(client, fip['port_id'])
        return self._format_floating_ip_model(fip, pool_dict, port_dict)

    def _get_floating_ip_pools(self, client, project_id=None):
        search_opts = {constants.NET_EXTERNAL: True}
        if project_id:
            search_opts.update({'tenant_id': project_id})
        data = client.list_networks(**search_opts)
        return data['networks']

    def get_floating_ip_pools(self, context):
        """Return floating ip pools."""
        client = neutronv2.get_client(context)
        pools = self._get_floating_ip_pools(client)
        return [{'name': n['name'] or n['id']} for n in pools]

    def _format_floating_ip_model(self, fip, pool_dict, port_dict):
        pool = pool_dict[fip['floating_network_id']]
        result = {'id': fip['id'],
                  'address': fip['floating_ip_address'],
                  'pool': pool['name'] or pool['id'],
                  'project_id': fip['tenant_id'],
                  # In Neutron v2, an exact fixed_ip_id does not exist.
                  'fixed_ip_id': fip['port_id'],
                  }
        # In Neutron v2 API fixed_ip_address and instance uuid
        # (= device_id) are known here, so pass it as a result.
        result['fixed_ip'] = {'address': fip['fixed_ip_address']}
        if fip['port_id']:
            instance_uuid = port_dict[fip['port_id']]['device_id']
            result['instance'] = {'uuid': instance_uuid}
        else:
            result['instance'] = None
        return result

    def get_floating_ip_by_address(self, context, address):
        """Return a floating ip given an address."""
        client = neutronv2.get_client(context)
        fip = self._get_floating_ip_by_address(client, address)
        pool_dict = self._setup_net_dict(client,
                                         fip['floating_network_id'])
        port_dict = self._setup_port_dict(client, fip['port_id'])
        return self._format_floating_ip_model(fip, pool_dict, port_dict)

    def get_floating_ips_by_project(self, context):
        client = neutronv2.get_client(context)
        project_id = context.project_id
        fips = client.list_floatingips(tenant_id=project_id)['floatingips']
        pool_dict = self._setup_pools_dict(client)
        port_dict = self._setup_ports_dict(client, project_id)
        return [self._format_floating_ip_model(fip, pool_dict, port_dict)
                for fip in fips]

    def get_floating_ips_by_fixed_address(self, context, fixed_address):
        raise NotImplementedError()

    def get_instance_id_by_floating_address(self, context, address):
        """Return the instance id a floating ip's fixed ip is allocated to."""
        client = neutronv2.get_client(context)
        fip = self._get_floating_ip_by_address(client, address)
        if not fip['port_id']:
            return None
        port = client.show_port(fip['port_id'])['port']
        return port['device_id']

    def get_vifs_by_instance(self, context, instance):
        raise NotImplementedError()

    def get_vif_by_mac_address(self, context, mac_address):
        raise NotImplementedError()

    def _get_floating_ip_pool_id_by_name_or_id(self, client, name_or_id):
        search_opts = {constants.NET_EXTERNAL: True, 'fields': 'id'}
        if uuidutils.is_uuid_like(name_or_id):
            search_opts.update({'id': name_or_id})
        else:
            search_opts.update({'name': name_or_id})
        data = client.list_networks(**search_opts)
        nets = data['networks']

        if len(nets) == 1:
            return nets[0]['id']
        elif len(nets) == 0:
            raise exception.FloatingIpPoolNotFound()
        else:
            msg = (_("Multiple floating IP pools matches found for name '%s'")
                   % name_or_id)
            raise exception.NovaException(message=msg)

    def allocate_floating_ip(self, context, pool=None):
        """Add a floating ip to a project from a pool."""
        client = neutronv2.get_client(context)
        pool = pool or CONF.default_floating_pool
        pool_id = self._get_floating_ip_pool_id_by_name_or_id(client, pool)

        # TODO(amotoki): handle exception during create_floatingip()
        # At this timing it is ensured that a network for pool exists.
        # quota error may be returned.
        param = {'floatingip': {'floating_network_id': pool_id}}
        try:
            fip = client.create_floatingip(param)
        except (neutron_client_exc.IpAddressGenerationFailureClient,
                neutron_client_exc.ExternalIpAddressExhaustedClient) as e:
            raise exception.NoMoreFloatingIps(unicode(e))
        return fip['floatingip']['floating_ip_address']

    def _get_floating_ip_by_address(self, client, address):
        """Get floatingip from floating ip address."""
        if not address:
            raise exception.FloatingIpNotFoundForAddress(address=address)
        data = client.list_floatingips(floating_ip_address=address)
        fips = data['floatingips']
        if len(fips) == 0:
            raise exception.FloatingIpNotFoundForAddress(address=address)
        elif len(fips) > 1:
            raise exception.FloatingIpMultipleFoundForAddress(address=address)
        return fips[0]

    def _get_floating_ips_by_fixed_and_port(self, client, fixed_ip, port):
        """Get floatingips from fixed ip and port."""
        try:
            data = client.list_floatingips(fixed_ip_address=fixed_ip,
                                           port_id=port)
        # If a neutron plugin does not implement the L3 API a 404 from
        # list_floatingips will be raised.
        except neutronv2.exceptions.NeutronClientException as e:
            if e.status_code == 404:
                return []
            with excutils.save_and_reraise_exception():
                LOG.exception(_('Unable to access floating IP %(fixed_ip)s '
                                'for port %(port_id)s'),
                              {'fixed_ip': fixed_ip, 'port_id': port})
        return data['floatingips']

    def release_floating_ip(self, context, address,
                            affect_auto_assigned=False):
        """Remove a floating ip with the given address from a project."""

        # Note(amotoki): We cannot handle a case where multiple pools
        # have overlapping IP address range. In this case we cannot use
        # 'address' as a unique key.
        # This is a limitation of the current nova.

        # Note(amotoki): 'affect_auto_assigned' is not respected
        # since it is not used anywhere in nova code and I could
        # find why this parameter exists.

        self._release_floating_ip(context, address)

    def disassociate_and_release_floating_ip(self, context, instance,
                                           floating_ip):
        """Removes (deallocates) and deletes the floating ip.

        This api call was added to allow this to be done in one operation
        if using neutron.
        """
        self._release_floating_ip(context, floating_ip['address'],
                                  raise_if_associated=False)

    def _release_floating_ip(self, context, address,
                             raise_if_associated=True):
        client = neutronv2.get_client(context)
        fip = self._get_floating_ip_by_address(client, address)

        if raise_if_associated and fip['port_id']:
            raise exception.FloatingIpAssociated(address=address)
        client.delete_floatingip(fip['id'])

    @refresh_cache
    def disassociate_floating_ip(self, context, instance, address,
                                 affect_auto_assigned=False):
        """Disassociate a floating ip from the instance."""

        # Note(amotoki): 'affect_auto_assigned' is not respected
        # since it is not used anywhere in nova code and I could
        # find why this parameter exists.

        client = neutronv2.get_client(context)
        fip = self._get_floating_ip_by_address(client, address)
        client.update_floatingip(fip['id'], {'floatingip': {'port_id': None}})

    def migrate_instance_start(self, context, instance, migration):
        """Start to migrate the network of an instance."""
        # NOTE(wenjianhn): just pass to make migrate instance doesn't
        # raise for now.
        pass

    def migrate_instance_finish(self, context, instance, migration):
        """Finish migrating the network of an instance."""
        if not self._has_port_binding_extension(context, refresh_cache=True):
            return
        neutron = neutronv2.get_client(context, admin=True)
        search_opts = {'device_id': instance['uuid'],
                       'tenant_id': instance['project_id']}
        data = neutron.list_ports(**search_opts)
        ports = data['ports']
        for p in ports:
            port_req_body = {'port': {'binding:host_id':
                                      migration['dest_compute']}}
            try:
                neutron.update_port(p['id'], port_req_body)
            except Exception:
                with excutils.save_and_reraise_exception():
                    msg = _("Unable to update host of port %s")
                    LOG.exception(msg, p['id'])

    def add_network_to_project(self, context, project_id, network_uuid=None):
        """Force add a network to the project."""
        raise NotImplementedError()

    def _nw_info_get_ips(self, client, port):
        network_IPs = []
        for fixed_ip in port['fixed_ips']:
            fixed = network_model.FixedIP(address=fixed_ip['ip_address'])
            floats = self._get_floating_ips_by_fixed_and_port(
                client, fixed_ip['ip_address'], port['id'])
            for ip in floats:
                fip = network_model.IP(address=ip['floating_ip_address'],
                                       type='floating')
                fixed.add_floating_ip(fip)
            network_IPs.append(fixed)
        return network_IPs

    def _nw_info_get_subnets(self, context, port, network_IPs):
        subnets = self._get_subnets_from_port(context, port)
        for subnet in subnets:
            subnet['ips'] = [fixed_ip for fixed_ip in network_IPs
                             if fixed_ip.is_in_subnet(subnet)]
        return subnets

    def _nw_info_build_network(self, port, networks, subnets):
        network_name = None
        for net in networks:
            if port['network_id'] == net['id']:
                network_name = net['name']
                tenant_id = net['tenant_id']
                break
        else:
            tenant_id = port['tenant_id']
            LOG.warning(_("Network %(id)s not matched with the tenants "
                          "network! The ports tenant %(tenant_id)s will be "
                          "used."),
                        {'id': port['network_id'], 'tenant_id': tenant_id})

        bridge = None
        ovs_interfaceid = None
        # Network model metadata
        should_create_bridge = None
        vif_type = port.get('binding:vif_type')
        # TODO(berrange) Neutron should pass the bridge name
        # in another binding metadata field
        if vif_type == network_model.VIF_TYPE_OVS:
            bridge = CONF.neutron_ovs_bridge
            ovs_interfaceid = port['id']
        elif vif_type == network_model.VIF_TYPE_BRIDGE:
            bridge = "brq" + port['network_id']
            should_create_bridge = True

        if bridge is not None:
            bridge = bridge[:network_model.NIC_NAME_LEN]

        network = network_model.Network(
            id=port['network_id'],
            bridge=bridge,
            injected=CONF.flat_injected,
            label=network_name,
            tenant_id=tenant_id
            )
        network['subnets'] = subnets
        port_profile = port.get('binding:profile')
        if port_profile:
            physical_network = port_profile.get('physical_network')
            if physical_network:
                network['physical_network'] = physical_network

        if should_create_bridge is not None:
            network['should_create_bridge'] = should_create_bridge
        return network, ovs_interfaceid

    def _build_network_info_model(self, context, instance, networks=None,
                                  port_ids=None):
        """Return list of ordered VIFs attached to instance.

        :param context - request context.
        :param instance - instance we are returning network info for.
        :param networks - List of networks being attached to an instance.
                          If value is None this value will be populated
                          from the existing cached value.
        :param port_ids - List of port_ids that are being attached to an
                          instance in order of attachment. If value is None
                          this value will be populated from the existing
                          cached value.
        """

        search_opts = {'tenant_id': instance['project_id'],
                       'device_id': instance['uuid'], }
        client = neutronv2.get_client(context, admin=True)
        data = client.list_ports(**search_opts)

        current_neutron_ports = data.get('ports', [])
        networks, port_ids = self._gather_port_ids_and_networks(
                context, instance, networks, port_ids)
        nw_info = network_model.NetworkInfo()

        current_neutron_port_map = {}
        for current_neutron_port in current_neutron_ports:
            current_neutron_port_map[current_neutron_port['id']] = (
                current_neutron_port)

        for port_id in port_ids:
            current_neutron_port = current_neutron_port_map.get(port_id)
            if current_neutron_port:
                vif_active = False
                if (current_neutron_port['admin_state_up'] is False
                    or current_neutron_port['status'] == 'ACTIVE'):
                    vif_active = True

                network_IPs = self._nw_info_get_ips(client,
                                                    current_neutron_port)
                subnets = self._nw_info_get_subnets(context,
                                                    current_neutron_port,
                                                    network_IPs)

                devname = "tap" + current_neutron_port['id']
                devname = devname[:network_model.NIC_NAME_LEN]

                network, ovs_interfaceid = (
                    self._nw_info_build_network(current_neutron_port,
                                                networks, subnets))

                nw_info.append(network_model.VIF(
                    id=current_neutron_port['id'],
                    address=current_neutron_port['mac_address'],
                    network=network,
                    type=current_neutron_port.get('binding:vif_type'),
                    details=current_neutron_port.get('binding:vif_details'),
                    ovs_interfaceid=ovs_interfaceid,
                    devname=devname,
                    active=vif_active))

        return nw_info

    def _get_subnets_from_port(self, context, port):
        """Return the subnets for a given port."""

        fixed_ips = port['fixed_ips']
        # No fixed_ips for the port means there is no subnet associated
        # with the network the port is created on.
        # Since list_subnets(id=[]) returns all subnets visible for the
        # current tenant, returned subnets may contain subnets which is not
        # related to the port. To avoid this, the method returns here.
        if not fixed_ips:
            return []
        search_opts = {'id': [ip['subnet_id'] for ip in fixed_ips]}
        data = neutronv2.get_client(context).list_subnets(**search_opts)
        ipam_subnets = data.get('subnets', [])
        subnets = []

        for subnet in ipam_subnets:
            subnet_dict = {'cidr': subnet['cidr'],
                           'gateway': network_model.IP(
                                address=subnet['gateway_ip'],
                                type='gateway'),
            }

            # attempt to populate DHCP server field
            search_opts = {'network_id': subnet['network_id'],
                           'device_owner': 'network:dhcp'}
            data = neutronv2.get_client(context).list_ports(**search_opts)
            dhcp_ports = data.get('ports', [])
            for p in dhcp_ports:
                for ip_pair in p['fixed_ips']:
                    if ip_pair['subnet_id'] == subnet['id']:
                        subnet_dict['dhcp_server'] = ip_pair['ip_address']
                        break

            subnet_object = network_model.Subnet(**subnet_dict)
            for dns in subnet.get('dns_nameservers', []):
                subnet_object.add_dns(
                    network_model.IP(address=dns, type='dns'))

            # TODO(gongysh) get the routes for this subnet
            subnets.append(subnet_object)
        return subnets

    def get_dns_domains(self, context):
        """Return a list of available dns domains.

        These can be used to create DNS entries for floating ips.
        """
        raise NotImplementedError()

    def add_dns_entry(self, context, address, name, dns_type, domain):
        """Create specified DNS entry for address."""
        raise NotImplementedError()

    def modify_dns_entry(self, context, name, address, domain):
        """Create specified DNS entry for address."""
        raise NotImplementedError()

    def delete_dns_entry(self, context, name, domain):
        """Delete the specified dns entry."""
        raise NotImplementedError()

    def delete_dns_domain(self, context, domain):
        """Delete the specified dns domain."""
        raise NotImplementedError()

    def get_dns_entries_by_address(self, context, address, domain):
        """Get entries for address and domain."""
        raise NotImplementedError()

    def get_dns_entries_by_name(self, context, name, domain):
        """Get entries for name and domain."""
        raise NotImplementedError()

    def create_private_dns_domain(self, context, domain, availability_zone):
        """Create a private DNS domain with nova availability zone."""
        raise NotImplementedError()

    def create_public_dns_domain(self, context, domain, project=None):
        """Create a private DNS domain with optional nova project."""
        raise NotImplementedError()


def _ensure_requested_network_ordering(accessor, unordered, preferred):
    """Sort a list with respect to the preferred network ordering."""
    if preferred:
        unordered.sort(key=lambda i: preferred.index(accessor(i)))
