# Copyright(c) 2016 Nippon Telegraph and Telephone Corporation
#
# 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.

"""Base Manager class.

Managers are responsible for a certain aspect of the system. It is a logical
grouping of code relating to a portion of the system. In general other
components should be using the manager to make changes to the components that
it is responsible for.

We have adopted a basic strategy of Smart managers and dumb data, which means
rather than attaching methods to data objects, components should call manager
methods that act on the data.

Methods on managers that can be executed locally should be called directly. If
a particular method must execute on a remote host, this should be done via rpc
to the service that wraps the manager.

Managers should be responsible for most of the db access, and
non-implementation specific data.  Anything implementation specific that can't
be generalized should be done by the Driver.

Managers will often provide methods for initial setup of a host or periodic
tasks to a wrapping service.

This module provides Manager, a base class for managers.

"""

from oslo_service import periodic_task

import masakarimonitors.conf


CONF = masakarimonitors.conf.CONF


class PeriodicTasks(periodic_task.PeriodicTasks):
    def __init__(self):
        super(PeriodicTasks, self).__init__(CONF)


class Manager(PeriodicTasks):

    def __init__(self, host=None, service_name='undefined'):
        if not host:
            host = CONF.hostname
        self.host = host
        self.service_name = service_name
        super(Manager, self).__init__()

    def periodic_tasks(self, context, raise_on_error=False):
        """Tasks to be run at a periodic interval."""
        return self.run_periodic_tasks(context, raise_on_error=raise_on_error)

    def init_host(self):
        """Hook to do additional manager initialization when one requests

        the service be started. This is called before any service record
        is created.

        Child classes should override this method.
        """
        pass

    def cleanup_host(self):
        """Hook to do cleanup work when the service shuts down.

        Child classes should override this method.
        """
        pass

    def pre_start_hook(self):
        """Hook to provide the manager the ability to do additional

        start-up work before any RPC queues/consumers are created. This is
        called after other initialization has succeeded and a service
        record is created.

        Child classes should override this method.
        """
        pass

    def post_start_hook(self):
        """Hook to provide the manager the ability to do additional

        start-up work immediately after a service creates RPC consumers
        and starts 'running'.

        Child classes should override this method.
        """
        pass

    def reset(self):
        """Hook called on SIGHUP to signal the manager to re-read any

        dynamic configuration or do any reconfiguration tasks.
        """
        pass
