# Copyright (c) 2012 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 datetime import datetime
import itertools

from oslo_log import log as logging
import oslo_messaging
from oslo_utils import uuidutils

from neutron.common import constants
from neutron.common import rpc as n_rpc
from neutron.common import topics
from neutron.i18n import _LW


LOG = logging.getLogger(__name__)


def create_consumers(endpoints, prefix, topic_details, start_listening=True):
    """Create agent RPC consumers.

    :param endpoints: The list of endpoints to process the incoming messages.
    :param prefix: Common prefix for the plugin/agent message queues.
    :param topic_details: A list of topics. Each topic has a name, an
                          operation, and an optional host param keying the
                          subscription to topic.host for plugin calls.
    :param start_listening: if True, it starts the processing loop

    :returns: A common Connection.
    """

    connection = n_rpc.create_connection(new=True)
    for details in topic_details:
        topic, operation, node_name = itertools.islice(
            itertools.chain(details, [None]), 3)

        topic_name = topics.get_topic_name(prefix, topic, operation)
        connection.create_consumer(topic_name, endpoints, fanout=True)
        if node_name:
            node_topic_name = '%s.%s' % (topic_name, node_name)
            connection.create_consumer(node_topic_name,
                                       endpoints,
                                       fanout=False)
    if start_listening:
        connection.consume_in_threads()
    return connection


class PluginReportStateAPI(object):
    """RPC client used to report state back to plugin.

    This class implements the client side of an rpc interface.  The server side
    can be found in neutron.db.agents_db.AgentExtRpcCallback.  For more
    information on changing rpc interfaces, see doc/source/devref/rpc_api.rst.
    """
    def __init__(self, topic):
        target = oslo_messaging.Target(topic=topic, version='1.0',
                                       namespace=constants.RPC_NAMESPACE_STATE)
        self.client = n_rpc.get_client(target)

    def report_state(self, context, agent_state, use_call=False):
        cctxt = self.client.prepare()
        # add unique identifier to a report
        # that can be logged on server side.
        # This create visible correspondence between events on
        # the agent and on the server
        agent_state['uuid'] = uuidutils.generate_uuid()
        kwargs = {
            'agent_state': {'agent_state': agent_state},
            'time': datetime.utcnow().strftime(constants.ISO8601_TIME_FORMAT),
        }
        method = cctxt.call if use_call else cctxt.cast
        return method(context, 'report_state', **kwargs)


class PluginApi(object):
    '''Agent side of the rpc API.

    API version history:
        1.0 - Initial version.
        1.3 - get_device_details rpc signature upgrade to obtain 'host' and
              return value to include fixed_ips and device_owner for
              the device port
        1.4 - tunnel_sync rpc signature upgrade to obtain 'host'
    '''

    def __init__(self, topic):
        target = oslo_messaging.Target(topic=topic, version='1.0')
        self.client = n_rpc.get_client(target)

    def get_device_details(self, context, device, agent_id, host=None):
        cctxt = self.client.prepare()
        return cctxt.call(context, 'get_device_details', device=device,
                          agent_id=agent_id, host=host)

    def get_devices_details_list(self, context, devices, agent_id, host=None):
        try:
            cctxt = self.client.prepare(version='1.3')
            res = cctxt.call(context, 'get_devices_details_list',
                             devices=devices, agent_id=agent_id, host=host)
        except oslo_messaging.UnsupportedVersion:
            # If the server has not been upgraded yet, a DVR-enabled agent
            # may not work correctly, however it can function in 'degraded'
            # mode, in that DVR routers may not be in the system yet, and
            # it might be not necessary to retrieve info about the host.
            LOG.warn(_LW('DVR functionality requires a server upgrade.'))
            res = [
                self.get_device_details(context, device, agent_id, host)
                for device in devices
            ]
        return res

    def update_device_down(self, context, device, agent_id, host=None):
        cctxt = self.client.prepare()
        return cctxt.call(context, 'update_device_down', device=device,
                          agent_id=agent_id, host=host)

    def update_device_up(self, context, device, agent_id, host=None):
        cctxt = self.client.prepare()
        return cctxt.call(context, 'update_device_up', device=device,
                          agent_id=agent_id, host=host)

    def tunnel_sync(self, context, tunnel_ip, tunnel_type=None, host=None):
        try:
            cctxt = self.client.prepare(version='1.4')
            res = cctxt.call(context, 'tunnel_sync', tunnel_ip=tunnel_ip,
                             tunnel_type=tunnel_type, host=host)
        except oslo_messaging.UnsupportedVersion:
            LOG.warn(_LW('Tunnel synchronization requires a server upgrade.'))
            cctxt = self.client.prepare()
            res = cctxt.call(context, 'tunnel_sync', tunnel_ip=tunnel_ip,
                             tunnel_type=tunnel_type)
        return res