# 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.

import sqlalchemy as sql

from keystone.common.sql import migration_helpers


_PROJECT_TABLE_NAME = 'project'
_PARENT_ID_COLUMN_NAME = 'parent_id'


def list_constraints(project_table):
    constraints = [{'table': project_table,
                    'fk_column': _PARENT_ID_COLUMN_NAME,
                    'ref_column': project_table.c.id}]

    return constraints


def upgrade(migrate_engine):
    meta = sql.MetaData()
    meta.bind = migrate_engine

    project_table = sql.Table(_PROJECT_TABLE_NAME, meta, autoload=True)
    parent_id = sql.Column(_PARENT_ID_COLUMN_NAME, sql.String(64),
                           nullable=True)
    project_table.create_column(parent_id)

    if migrate_engine.name == 'sqlite':
        return
    migration_helpers.add_constraints(list_constraints(project_table))