# Copyright (c) 2014 Red Hat, Inc.
# 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 oslo_config import cfg
from oslo_log import log as logging
import oslo_messaging

from tacker.common import rpc as n_rpc
from tacker.openstack.common import service


LOG = logging.getLogger(__name__)


class RpcProxy(object):
    '''Emulates RpcProxy class behaviour using oslo.messaging.

    This class is created to facilitate migration from oslo-incubator
    RPC layer implementation to oslo.messaging and is intended to
    emulate RpcProxy class behaviour using oslo.messaging API once the
    migration is applied.
    '''
    RPC_API_NAMESPACE = None

    def __init__(self, topic, default_version, version_cap=None):
        self.topic = topic
        target = oslo_messaging.Target(topic=topic, version=default_version)
        self._client = n_rpc.get_client(target, version_cap=version_cap)

    def make_msg(self, method, **kwargs):
        return {'method': method,
                'namespace': self.RPC_API_NAMESPACE,
                'args': kwargs}

    def call(self, context, msg, **kwargs):
        return self.__call_rpc_method(
            context, msg, rpc_method='call', **kwargs)

    def cast(self, context, msg, **kwargs):
        self.__call_rpc_method(context, msg, rpc_method='cast', **kwargs)

    def fanout_cast(self, context, msg, **kwargs):
        kwargs['fanout'] = True
        self.__call_rpc_method(context, msg, rpc_method='cast', **kwargs)

    def __call_rpc_method(self, context, msg, **kwargs):
        options = dict(
            ((opt, kwargs[opt])
             for opt in ('fanout', 'timeout', 'topic', 'version')
             if kwargs.get(opt))
        )
        if msg['namespace']:
            options['namespace'] = msg['namespace']

        if options:
            callee = self._client.prepare(**options)
        else:
            callee = self._client

        func = getattr(callee, kwargs['rpc_method'])
        return func(context, msg['method'], **msg['args'])


class RpcCallback(object):
    '''Sets callback version using oslo.messaging API.

    This class is created to facilitate migration from oslo-incubator
    RPC layer implementation to oslo.messaging and is intended to set
    callback version using oslo.messaging API once the migration is
    applied.
    '''
    RPC_API_VERSION = '1.0'

    def __init__(self):
        super(RpcCallback, self).__init__()
        self.target = oslo_messaging.Target(version=self.RPC_API_VERSION)


class Service(service.Service):
    """Service object for binaries running on hosts.

    A service enables rpc by listening to queues based on topic and host.
    """
    def __init__(self, host, topic, manager=None, serializer=None):
        super(Service, self).__init__()
        self.host = host
        self.topic = topic
        self.serializer = serializer
        if manager is None:
            self.manager = self
        else:
            self.manager = manager

    def start(self):
        super(Service, self).start()

        self.conn = create_connection(new=True)
        LOG.debug("Creating Consumer connection for Service %s",
                  self.topic)

        endpoints = [self.manager]

        # Share this same connection for these Consumers
        self.conn.create_consumer(self.topic, endpoints, fanout=False)

        node_topic = '%s.%s' % (self.topic, self.host)
        self.conn.create_consumer(node_topic, endpoints, fanout=False)

        self.conn.create_consumer(self.topic, endpoints, fanout=True)

        # Hook to allow the manager to do other initializations after
        # the rpc connection is created.
        if callable(getattr(self.manager, 'initialize_service_hook', None)):
            self.manager.initialize_service_hook(self)

        # Consume from all consumers in threads
        self.conn.consume_in_threads()

    def stop(self):
        # Try to shut the connection down, but if we get any sort of
        # errors, go ahead and ignore them.. as we're shutting down anyway
        try:
            self.conn.close()
        except Exception:
            pass
        super(Service, self).stop()


class Connection(object):

    def __init__(self):
        super(Connection, self).__init__()
        self.servers = []

    def create_consumer(self, topic, endpoints, fanout=False):
        target = oslo_messaging.Target(
            topic=topic, server=cfg.CONF.host, fanout=fanout)
        server = n_rpc.get_server(target, endpoints)
        self.servers.append(server)

    def consume_in_threads(self):
        for server in self.servers:
            server.start()
        return self.servers


# functions
def create_connection(new=True):
    return Connection()


# exceptions
RPCException = oslo_messaging.MessagingException
RemoteError = oslo_messaging.RemoteError
MessagingTimeout = oslo_messaging.MessagingTimeout