# Copyright 2016 Huawei Technologies India Pvt. Ltd.
# 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.

import abc

from neutron.api import extensions
from neutron.api.v2 import resource
from neutron import wsgi
from neutron_lib.api import extensions as api_extensions
from neutron_lib.api import faults
from neutron_lib import exceptions as n_exc
from neutron_lib.exceptions import agent as agent_exc
from neutron_lib.plugins import directory
from oslo_log import log as logging
import webob

from neutron_dynamic_routing._i18n import _, _LE
from neutron_dynamic_routing.extensions import bgp as bgp_ext


LOG = logging.getLogger(__name__)

BGP_DRAGENT_SCHEDULER_EXT_ALIAS = 'bgp_dragent_scheduler'
BGP_DRINSTANCE = 'bgp-drinstance'
BGP_DRINSTANCES = BGP_DRINSTANCE + 's'
BGP_DRAGENT = 'bgp-dragent'
BGP_DRAGENTS = BGP_DRAGENT + 's'


class DrAgentInvalid(agent_exc.AgentNotFound):
    message = _("BgpDrAgent %(id)s is invalid or has been disabled.")


class DrAgentNotHostingBgpSpeaker(n_exc.NotFound):
    message = _("BGP speaker %(bgp_speaker_id)s is not hosted "
                "by the BgpDrAgent %(agent_id)s.")


class DrAgentAssociationError(n_exc.Conflict):
    message = _("BgpDrAgent %(agent_id)s is already associated "
                "to a BGP speaker.")


class BgpSpeakerRescheduleError(n_exc.Conflict):
    message = _("Failed rescheduling %(bgp_speaker_id)s: "
                "%(failure_reason)s.")


class BgpDrSchedulerController(wsgi.Controller):
    """Schedule BgpSpeaker for a BgpDrAgent"""
    def get_plugin(self):
        plugin = directory.get_plugin(bgp_ext.BGP_EXT_ALIAS)
        if not plugin:
            LOG.error(_LE('No plugin for BGP routing registered'))
            msg = _('The resource could not be found.')
            raise webob.exc.HTTPNotFound(msg)
        return plugin

    def index(self, request, **kwargs):
        plugin = self.get_plugin()
        return plugin.list_bgp_speaker_on_dragent(
            request.context, kwargs['agent_id'])

    def create(self, request, body, **kwargs):
        plugin = self.get_plugin()
        return plugin.add_bgp_speaker_to_dragent(
            request.context,
            kwargs['agent_id'],
            body['bgp_speaker_id'])

    def delete(self, request, id, **kwargs):
        plugin = self.get_plugin()
        return plugin.remove_bgp_speaker_from_dragent(
            request.context, kwargs['agent_id'], id)


class BgpDrAgentController(wsgi.Controller):
    def get_plugin(self):
        plugin = directory.get_plugin(bgp_ext.BGP_EXT_ALIAS)
        if not plugin:
            LOG.error(_LE('No plugin for BGP routing registered'))
            msg = _('The resource could not be found.')
            raise webob.exc.HTTPNotFound(msg)
        return plugin

    def index(self, request, **kwargs):
        plugin = directory.get_plugin(bgp_ext.BGP_EXT_ALIAS)
        return plugin.list_dragent_hosting_bgp_speaker(
            request.context, kwargs['bgp_speaker_id'])


class Bgp_dragentscheduler(api_extensions.ExtensionDescriptor):
    """Extension class supporting Dynamic Routing scheduler.
    """
    @classmethod
    def get_name(cls):
        return "BGP Dynamic Routing Agent Scheduler"

    @classmethod
    def get_alias(cls):
        return BGP_DRAGENT_SCHEDULER_EXT_ALIAS

    @classmethod
    def get_description(cls):
        return "Schedules BgpSpeakers on BgpDrAgent"

    @classmethod
    def get_updated(cls):
        return "2015-07-30T10:00:00-00:00"

    @classmethod
    def get_resources(cls):
        """Returns Ext Resources."""
        exts = []
        parent = dict(member_name="agent",
                      collection_name="agents")

        controller = resource.Resource(BgpDrSchedulerController(),
                                       faults.FAULT_MAP)
        exts.append(extensions.ResourceExtension(BGP_DRINSTANCES,
                                                 controller, parent))

        parent = dict(member_name="bgp_speaker",
                      collection_name="bgp-speakers")
        controller = resource.Resource(BgpDrAgentController(),
                                       faults.FAULT_MAP)
        exts.append(extensions.ResourceExtension(BGP_DRAGENTS,
                                                 controller, parent))
        return exts

    def get_extended_resources(self, version):
        return {}


class BgpDrSchedulerPluginBase(object, metaclass=abc.ABCMeta):
    """REST API to operate BGP dynamic routing agent scheduler.

    All the methods must be executed in admin context.
    """
    def get_plugin_description(self):
        return "Neutron BGP dynamic routing scheduler Plugin"

    def get_plugin_type(self):
        return bgp_ext.BGP_EXT_ALIAS

    @abc.abstractmethod
    def add_bgp_speaker_to_dragent(self, context, agent_id, speaker_id):
        pass

    @abc.abstractmethod
    def remove_bgp_speaker_from_dragent(self, context, agent_id, speaker_id):
        pass

    @abc.abstractmethod
    def list_dragent_hosting_bgp_speaker(self, context, speaker_id):
        pass

    @abc.abstractmethod
    def list_bgp_speaker_on_dragent(self, context, agent_id):
        pass

    @abc.abstractmethod
    def get_bgp_speakers_for_agent_host(self, context, host):
        pass

    @abc.abstractmethod
    def get_bgp_speaker_by_speaker_id(self, context, speaker_id):
        pass

    @abc.abstractmethod
    def get_bgp_peer_by_peer_id(self, context, bgp_peer_id):
        pass