# Copyright 2013 Red Hat, Inc.
#
#    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.

__all__ = [
    'init',
    'cleanup',
    'set_defaults',
    'add_extra_exmods',
    'clear_extra_exmods',
    'get_allowed_exmods',
    'RequestContextSerializer',
    'get_client',
    'get_server',
    'get_notifier',
    'TRANSPORT_ALIASES',
]

from oslo_config import cfg
import oslo_messaging as messaging
from oslo_serialization import jsonutils

import nova.context
import nova.exception


CONF = cfg.CONF
notification_opts = [
    cfg.StrOpt('notification_format',
               choices=['unversioned', 'versioned', 'both'],
               default='both',
               help='Specifies which notification format shall be used by '
                    'nova.'),
]

CONF.register_opts(notification_opts)

TRANSPORT = None
LEGACY_NOTIFIER = None
NOTIFICATION_TRANSPORT = None
NOTIFIER = None

ALLOWED_EXMODS = [
    nova.exception.__name__,
]
EXTRA_EXMODS = []

# NOTE(markmc): The nova.openstack.common.rpc entries are for backwards compat
# with Havana rpc_backend configuration values. The nova.rpc entries are for
# compat with Essex values.
TRANSPORT_ALIASES = {
    'nova.openstack.common.rpc.impl_kombu': 'rabbit',
    'nova.openstack.common.rpc.impl_qpid': 'qpid',
    'nova.openstack.common.rpc.impl_zmq': 'zmq',
    'nova.rpc.impl_kombu': 'rabbit',
    'nova.rpc.impl_qpid': 'qpid',
    'nova.rpc.impl_zmq': 'zmq',
}


def init(conf):
    global TRANSPORT, NOTIFICATION_TRANSPORT, LEGACY_NOTIFIER, NOTIFIER
    exmods = get_allowed_exmods()
    TRANSPORT = messaging.get_transport(conf,
                                        allowed_remote_exmods=exmods,
                                        aliases=TRANSPORT_ALIASES)
    NOTIFICATION_TRANSPORT = messaging.get_notification_transport(
        conf, allowed_remote_exmods=exmods, aliases=TRANSPORT_ALIASES)
    serializer = RequestContextSerializer(JsonPayloadSerializer())
    if conf.notification_format == 'unversioned':
        LEGACY_NOTIFIER = messaging.Notifier(NOTIFICATION_TRANSPORT,
                                             serializer=serializer)
        NOTIFIER = messaging.Notifier(NOTIFICATION_TRANSPORT,
                                      serializer=serializer, driver='noop')
    elif conf.notification_format == 'both':
        LEGACY_NOTIFIER = messaging.Notifier(NOTIFICATION_TRANSPORT,
                                             serializer=serializer)
        NOTIFIER = messaging.Notifier(NOTIFICATION_TRANSPORT,
                                      serializer=serializer,
                                      topic='versioned_notifications')
    else:
        LEGACY_NOTIFIER = messaging.Notifier(NOTIFICATION_TRANSPORT,
                                             serializer=serializer,
                                             driver='noop')
        NOTIFIER = messaging.Notifier(NOTIFICATION_TRANSPORT,
                                      serializer=serializer,
                                      topic='versioned_notifications')


def cleanup():
    global TRANSPORT, NOTIFICATION_TRANSPORT, LEGACY_NOTIFIER, NOTIFIER
    assert TRANSPORT is not None
    assert NOTIFICATION_TRANSPORT is not None
    assert LEGACY_NOTIFIER is not None
    assert NOTIFIER is not None
    TRANSPORT.cleanup()
    NOTIFICATION_TRANSPORT.cleanup()
    TRANSPORT = NOTIFICATION_TRANSPORT = LEGACY_NOTIFIER = NOTIFIER = None


def set_defaults(control_exchange):
    messaging.set_transport_defaults(control_exchange)


def add_extra_exmods(*args):
    EXTRA_EXMODS.extend(args)


def clear_extra_exmods():
    del EXTRA_EXMODS[:]


def get_allowed_exmods():
    return ALLOWED_EXMODS + EXTRA_EXMODS


class JsonPayloadSerializer(messaging.NoOpSerializer):
    @staticmethod
    def serialize_entity(context, entity):
        return jsonutils.to_primitive(entity, convert_instances=True)


class RequestContextSerializer(messaging.Serializer):

    def __init__(self, base):
        self._base = base

    def serialize_entity(self, context, entity):
        if not self._base:
            return entity
        return self._base.serialize_entity(context, entity)

    def deserialize_entity(self, context, entity):
        if not self._base:
            return entity
        return self._base.deserialize_entity(context, entity)

    def serialize_context(self, context):
        return context.to_dict()

    def deserialize_context(self, context):
        return nova.context.RequestContext.from_dict(context)


def get_transport_url(url_str=None):
    return messaging.TransportURL.parse(CONF, url_str, TRANSPORT_ALIASES)


def get_client(target, version_cap=None, serializer=None):
    assert TRANSPORT is not None
    serializer = RequestContextSerializer(serializer)
    return messaging.RPCClient(TRANSPORT,
                               target,
                               version_cap=version_cap,
                               serializer=serializer)


def get_server(target, endpoints, serializer=None):
    assert TRANSPORT is not None
    serializer = RequestContextSerializer(serializer)
    return messaging.get_rpc_server(TRANSPORT,
                                    target,
                                    endpoints,
                                    executor='eventlet',
                                    serializer=serializer)


def get_notifier(service, host=None, publisher_id=None):
    assert LEGACY_NOTIFIER is not None
    if not publisher_id:
        publisher_id = "%s.%s" % (service, host or CONF.host)
    return LEGACY_NOTIFIER.prepare(publisher_id=publisher_id)


def get_versioned_notifier(publisher_id):
    assert NOTIFIER is not None
    return NOTIFIER.prepare(publisher_id=publisher_id)