# Copyright (c) 2011 Openstack, LLC.
# 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.

"""
Handles all requests relating to schedulers.
"""

from nova import flags
from nova import log as logging
from nova import rpc

FLAGS = flags.FLAGS
LOG = logging.getLogger('nova.scheduler.api')


def _call_scheduler(method, context, params=None):
    """Generic handler for RPC calls to the scheduler.

    :param params: Optional dictionary of arguments to be passed to the
                   scheduler worker

    :retval: Result returned by scheduler worker
    """
    if not params:
        params = {}
    queue = FLAGS.scheduler_topic
    kwargs = {'method': method, 'args': params}
    return rpc.call(context, queue, kwargs)


def get_zone_list(context):
    """Return a list of zones assoicated with this zone."""
    items = _call_scheduler('get_zone_list', context)
    for item in items:
        item['api_url'] = item['api_url'].replace('\\/', '/')
    return items


def get_zone_capabilities(context, service=None):
    """Returns a dict of key, value capabilities for this zone,
       or for a particular class of services running in this zone."""
    return _call_scheduler('get_zone_capabilities', context=context,
                          params=dict(service=service))


def update_service_capabilities(context, service_name, host, capabilities):
    """Send an update to all the scheduler services informing them
       of the capabilities of this service."""
    kwargs = dict(method='update_service_capabilities',
                  args=dict(service_name=service_name, host=host,
                            capabilities=capabilities))
    return rpc.fanout_cast(context, 'scheduler', kwargs)