text: # vim: tabstop=4 shiftwidth=4 softtabstop=4
  
  # Copyright (c) 2013 OpenStack Foundation.
  # 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.
  
  from abc import abstractmethod
  
  from neutron.api import extensions
  from neutron.api.v2 import base
  from neutron.api.v2 import resource
  from neutron.common import constants
  from neutron.common import exceptions
  from neutron.extensions import agent
  from neutron import manager
  from neutron import policy
  from neutron import wsgi
  
  DHCP_NET = 'dhcp-network'
  DHCP_NETS = DHCP_NET + 's'
  DHCP_AGENT = 'dhcp-agent'
  DHCP_AGENTS = DHCP_AGENT + 's'
  
  
  class NetworkSchedulerController(wsgi.Controller):
      def index(self, request, **kwargs):
          plugin = manager.NeutronManager.get_plugin()
          policy.enforce(request.context,
                         "get_%s" % DHCP_NETS,
                         {})
          return plugin.list_networks_on_dhcp_agent(
              request.context, kwargs['agent_id'])
  
      def create(self, request, body, **kwargs):
          plugin = manager.NeutronManager.get_plugin()
          policy.enforce(request.context,
                         "create_%s" % DHCP_NET,
                         {})
          return plugin.add_network_to_dhcp_agent(
              request.context, kwargs['agent_id'], body['network_id'])
  
      def delete(self, request, id, **kwargs):
          plugin = manager.NeutronManager.get_plugin()
          policy.enforce(request.context,
                         "delete_%s" % DHCP_NET,
                         {})
          return plugin.remove_network_from_dhcp_agent(
              request.context, kwargs['agent_id'], id)
  
  
  class DhcpAgentsHostingNetworkController(wsgi.Controller):
      def index(self, request, **kwargs):
          plugin = manager.NeutronManager.get_plugin()
          policy.enforce(request.context,
                         "get_%s" % DHCP_AGENTS,
                         {})
          return plugin.list_dhcp_agents_hosting_network(
              request.context, kwargs['network_id'])
  
  
  class Dhcpagentscheduler(extensions.ExtensionDescriptor):
      """Extension class supporting dhcp agent scheduler.
      """
  
      @classmethod
      def get_name(cls):
          return "DHCP Agent Scheduler"
  
      @classmethod
      def get_alias(cls):
          return constants.DHCP_AGENT_SCHEDULER_EXT_ALIAS
  
      @classmethod
      def get_description(cls):
          return "Schedule networks among dhcp agents"
  
      @classmethod
      def get_namespace(cls):
          return "http://docs.openstack.org/ext/dhcp_agent_scheduler/api/v1.0"
  
      @classmethod
      def get_updated(cls):
          return "2013-02-07T10:00:00-00:00"
  
      @classmethod
      def get_resources(cls):
          """Returns Ext Resources."""
          exts = []
          parent = dict(member_name="agent",
                        collection_name="agents")
          controller = resource.Resource(NetworkSchedulerController(),
                                         base.FAULT_MAP)
          exts.append(extensions.ResourceExtension(
              DHCP_NETS, controller, parent))
  
          parent = dict(member_name="network",
                        collection_name="networks")
  
          controller = resource.Resource(DhcpAgentsHostingNetworkController(),
                                         base.FAULT_MAP)
          exts.append(extensions.ResourceExtension(
              DHCP_AGENTS, controller, parent))
          return exts
  
      def get_extended_resources(self, version):
          return {}
  
  
  class InvalidDHCPAgent(agent.AgentNotFound):
      message = _("Agent %(id)s is not a valid DHCP Agent or has been disabled")
  
  
  class NetworkHostedByDHCPAgent(exceptions.Conflict):
      message = _("The network %(network_id)s has been already hosted"
                  " by the DHCP Agent %(agent_id)s.")
  
  
  class NetworkNotHostedByDhcpAgent(exceptions.Conflict):
      message = _("The network %(network_id)s is not hosted"
                  " by the DHCP agent %(agent_id)s.")
  
  
  class DhcpAgentSchedulerPluginBase(object):
      """REST API to operate the DHCP agent scheduler.
  
      All of method must be in an admin context.
      """
  
      @abstractmethod
      def add_network_to_dhcp_agent(self, context, id, network_id):
          pass
  
      @abstractmethod
      def remove_network_from_dhcp_agent(self, context, id, network_id):
          pass
  
      @abstractmethod
      def list_networks_on_dhcp_agent(self, context, id):
          pass
  
      @abstractmethod
      def list_dhcp_agents_hosting_network(self, context, network_id):
          pass
  