# vim: tabstop=4 shiftwidth=4 softtabstop=4

# 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.

"""Policy Engine For Ceilometer"""

from ceilometer import utils
from ceilometer.openstack.common import cfg
from ceilometer.openstack.common import policy


OPTS = [
    cfg.StrOpt('policy_file',
               default='policy.json',
               help='JSON file representing policy'),
    cfg.StrOpt('policy_default_rule',
               default='default',
               help='Rule checked when requested rule is not found'),
    ]

cfg.CONF.register_opts(OPTS)

_POLICY_PATH = None
_POLICY_CACHE = {}


def init():
    global _POLICY_PATH
    global _POLICY_CACHE
    if not _POLICY_PATH:
        _POLICY_PATH = cfg.CONF.policy_file
    utils.read_cached_file(_POLICY_PATH, _POLICY_CACHE,
                           reload_func=_set_brain)


def _set_brain(data):
    default_rule = cfg.CONF.policy_default_rule
    policy.set_brain(policy.Brain.load_json(data, default_rule))


def check_is_admin(roles, project_id, project_name):
    """Whether or not roles contains 'admin' role according to policy setting.

    """
    init()

    match_list = ('rule:context_is_admin',)
    target = {}
    credentials = {
        'roles': roles,
        'project_id': project_id,
        'project_name': project_name,
    }

    return policy.enforce(match_list, target, credentials)