# 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 neutron.plugins.ml2 import db
from neutron.plugins.ml2 import driver_api as api


class MechanismDriverContext(object):
    """MechanismDriver context base class."""
    def __init__(self, plugin, plugin_context):
        self._plugin = plugin
        # This temporarily creates a reference loop, but the
        # lifetime of PortContext is limited to a single
        # method call of the plugin.
        self._plugin_context = plugin_context


class NetworkContext(MechanismDriverContext, api.NetworkContext):

    def __init__(self, plugin, plugin_context, network,
                 original_network=None):
        super(NetworkContext, self).__init__(plugin, plugin_context)
        self._network = network
        self._original_network = original_network
        self._segments = db.get_network_segments(plugin_context.session,
                                                 network['id'])

    @property
    def current(self):
        return self._network

    @property
    def original(self):
        return self._original_network

    @property
    def network_segments(self):
        return self._segments


class SubnetContext(MechanismDriverContext, api.SubnetContext):

    def __init__(self, plugin, plugin_context, subnet, original_subnet=None):
        super(SubnetContext, self).__init__(plugin, plugin_context)
        self._subnet = subnet
        self._original_subnet = original_subnet

    @property
    def current(self):
        return self._subnet

    @property
    def original(self):
        return self._original_subnet


class PortContext(MechanismDriverContext, api.PortContext):

    def __init__(self, plugin, plugin_context, port, network,
                 original_port=None):
        super(PortContext, self).__init__(plugin, plugin_context)
        self._port = port
        self._original_port = original_port
        self._network_context = NetworkContext(plugin, plugin_context,
                                               network)
        self._binding = db.ensure_port_binding(plugin_context.session,
                                               port['id'])

    @property
    def current(self):
        return self._port

    @property
    def original(self):
        return self._original_port

    @property
    def network(self):
        return self._network_context

    @property
    def bound_segment(self):
        id = self._binding.segment
        if id:
            for segment in self._network_context.network_segments:
                if segment[api.ID] == id:
                    return segment

    def host_agents(self, agent_type):
        return self._plugin.get_agents(self._plugin_context,
                                       filters={'agent_type': [agent_type],
                                                'host': [self._binding.host]})

    def set_binding(self, segment_id, vif_type, cap_port_filter):
        # REVISIT(rkukura): Pass extensible list of capabilities? Move
        # vif_type and capabilities to methods on the bound mechanism
        # driver?

        # TODO(rkukura) Verify binding allowed, segment in network
        self._binding.segment = segment_id
        self._binding.vif_type = vif_type
        self._binding.cap_port_filter = cap_port_filter