# Copyright (c) 2010 OpenStack Foundation
# Copyright 2010 United States Government as represented by the
# Administrator of the National Aeronautics and Space Administration.
# 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.

"""
Scheduler base class that all Schedulers should inherit from
"""

from oslo.config import cfg

from cinder import db
from cinder.i18n import _
from cinder.openstack.common import importutils
from cinder.openstack.common import timeutils
from cinder.volume import rpcapi as volume_rpcapi


scheduler_driver_opts = [
    cfg.StrOpt('scheduler_host_manager',
               default='cinder.scheduler.host_manager.HostManager',
               help='The scheduler host manager class to use'),
    cfg.IntOpt('scheduler_max_attempts',
               default=3,
               help='Maximum number of attempts to schedule an volume'),
]

CONF = cfg.CONF
CONF.register_opts(scheduler_driver_opts)


def volume_update_db(context, volume_id, host):
    '''Set the host and set the scheduled_at field of a volume.

    :returns: A Volume with the updated fields set properly.
    '''
    now = timeutils.utcnow()
    values = {'host': host, 'scheduled_at': now}
    return db.volume_update(context, volume_id, values)


def group_update_db(context, group_id, host):
    """Set the host and the scheduled_at field of a consistencygroup.

    :returns: A Consistencygroup with the updated fields set properly.
    """
    now = timeutils.utcnow()
    values = {'host': host, 'updated_at': now}
    return db.consistencygroup_update(context, group_id, values)


class Scheduler(object):
    """The base class that all Scheduler classes should inherit from."""

    def __init__(self):
        self.host_manager = importutils.import_object(
            CONF.scheduler_host_manager)
        self.volume_rpcapi = volume_rpcapi.VolumeAPI()

    def update_service_capabilities(self, service_name, host, capabilities):
        """Process a capability update from a service node."""
        self.host_manager.update_service_capabilities(service_name,
                                                      host,
                                                      capabilities)

    def host_passes_filters(self, context, volume_id, host, filter_properties):
        """Check if the specified host passes the filters."""
        raise NotImplementedError(_("Must implement host_passes_filters"))

    def find_retype_host(self, context, request_spec, filter_properties=None,
                         migration_policy='never'):
        """Find a host that can accept the volume with its new type."""
        raise NotImplementedError(_("Must implement find_retype_host"))

    def schedule(self, context, topic, method, *_args, **_kwargs):
        """Must override schedule method for scheduler to work."""
        raise NotImplementedError(_("Must implement a fallback schedule"))

    def schedule_create_volume(self, context, request_spec, filter_properties):
        """Must override schedule method for scheduler to work."""
        raise NotImplementedError(_("Must implement schedule_create_volume"))

    def schedule_create_consistencygroup(self, context, group_id,
                                         request_spec_list,
                                         filter_properties_list):
        """Must override schedule method for scheduler to work."""
        raise NotImplementedError(_(
            "Must implement schedule_create_consistencygroup"))

    def get_pools(self, context, filters):
        """Must override schedule method for scheduler to work."""
        raise NotImplementedError(_(
            "Must implement schedule_get_pools"))
