# -*- encoding: utf-8 -*-
#
# Copyright © 2012 eNovance <licensing@enovance.com>
#
# 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.
#
# Copyright (c) 2017-2018 Wind River Systems, Inc.
#
# SPDX-License-Identifier: Apache-2.0
#

import signal

from oslo_log import log
import oslo_messaging as messaging
from oslo_service import service
from oslo_utils import importutils

from inventory.common import context
from inventory.common import rpc
from inventory.objects import base as objects_base

LOG = log.getLogger(__name__)


class RPCService(service.Service):

    def __init__(self, host, manager_module, manager_class):
        super(RPCService, self).__init__()
        self.host = host
        manager_module = importutils.try_import(manager_module)
        manager_class = getattr(manager_module, manager_class)
        self.manager = manager_class(host, manager_module.MANAGER_TOPIC)
        self.topic = self.manager.topic
        self.rpcserver = None
        self.deregister = True

    def start(self):
        super(RPCService, self).start()
        admin_context = context.get_admin_context()

        target = messaging.Target(topic=self.topic, server=self.host)
        endpoints = [self.manager]
        serializer = objects_base.InventoryObjectSerializer()
        self.rpcserver = rpc.get_server(target, endpoints, serializer)
        self.rpcserver.start()

        self.handle_signal()
        self.manager.init_host(admin_context)

        LOG.info('Created RPC server for service %(service)s on host '
                 '%(host)s.',
                 {'service': self.topic, 'host': self.host})

    def stop(self):
        try:
            self.rpcserver.stop()
            self.rpcserver.wait()
        except Exception as e:
            LOG.exception('Service error occurred when stopping the '
                          'RPC server. Error: %s', e)
        try:
            self.manager.del_host(deregister=self.deregister)
        except Exception as e:
            LOG.exception('Service error occurred when cleaning up '
                          'the RPC manager. Error: %s', e)

        super(RPCService, self).stop(graceful=True)
        LOG.info('Stopped RPC server for service %(service)s on host '
                 '%(host)s.',
                 {'service': self.topic, 'host': self.host})

    def _handle_signal(self, signo, frame):
        LOG.info('Got signal SIGUSR1. Not deregistering on next shutdown '
                 'of service %(service)s on host %(host)s.',
                 {'service': self.topic, 'host': self.host})
        self.deregister = False

    def handle_signal(self):
        """Add a signal handler for SIGUSR1.

        The handler ensures that the manager is not deregistered when it is
        shutdown.
        """
        signal.signal(signal.SIGUSR1, self._handle_signal)
