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# Copyright 2012 OpenStack LLC
#
# 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.

from keystone.common import sql
from keystone.common.sql import migration
from keystone import exception
from keystone.policy.backends import rules


class PolicyModel(sql.ModelBase, sql.DictBase):
    __tablename__ = 'policy'
    attributes = ['id', 'blob', 'type']
    id = sql.Column(sql.String(64), primary_key=True)
    blob = sql.Column(sql.JsonBlob(), nullable=False)
    type = sql.Column(sql.String(255), nullable=False)
    extra = sql.Column(sql.JsonBlob())


class Policy(sql.Base, rules.Policy):
    # Internal interface to manage the database
    def db_sync(self, version=None):
        migration.db_sync(version=version)

    @sql.handle_conflicts(type='policy')
    def create_policy(self, policy_id, policy):
        session = self.get_session()

        with session.begin():
            ref = PolicyModel.from_dict(policy)
            session.add(ref)
            session.flush()

        return ref.to_dict()

    def list_policies(self):
        session = self.get_session()

        refs = session.query(PolicyModel).all()
        return [ref.to_dict() for ref in refs]

    def _get_policy(self, session, policy_id):
        """Private method to get a policy model object (NOT a dictionary)."""
        ref = session.query(PolicyModel).get(policy_id)
        if not ref:
            raise exception.PolicyNotFound(policy_id=policy_id)
        return ref

    def get_policy(self, policy_id):
        session = self.get_session()

        return self._get_policy(session, policy_id).to_dict()

    @sql.handle_conflicts(type='policy')
    def update_policy(self, policy_id, policy):
        session = self.get_session()

        with session.begin():
            ref = self._get_policy(session, policy_id)
            old_dict = ref.to_dict()
            old_dict.update(policy)
            new_policy = PolicyModel.from_dict(old_dict)
            ref.blob = new_policy.blob
            ref.type = new_policy.type
            ref.extra = new_policy.extra
            session.flush()

        return ref.to_dict()

    def delete_policy(self, policy_id):
        session = self.get_session()

        with session.begin():
            ref = self._get_policy(session, policy_id)
            session.delete(ref)
            session.flush()
