#    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 uuid

from migrate import PrimaryKeyConstraint, ForeignKeyConstraint
from sqlalchemy import Column
from sqlalchemy import MetaData, String, Table


def upgrade(migrate_engine):
    """Add UUID primary key column to encryption."""
    meta = MetaData()
    meta.bind = migrate_engine

    encryptions = Table('encryption', meta, autoload=True)

    encryption_id = Column('encryption_id', String(36))
    encryptions.create_column(encryption_id)

    encryption_items = list(encryptions.select().execute())

    for item in encryption_items:
        encryptions.update().\
            where(encryptions.c.volume_type_id == item['volume_type_id']).\
            values(encryption_id=str(uuid.uuid4())).execute()

    # NOTE (e0ne): need to drop FK first for MySQL
    if migrate_engine.name == 'mysql':
        ref_table = Table('volume_types', meta, autoload=True)
        params = {'columns': [encryptions.c['volume_type_id']],
                  'refcolumns': [ref_table.c['id']],
                  'name': 'encryption_ibfk_1'}
        volume_type_fk = ForeignKeyConstraint(**params)
        volume_type_fk.drop()

    try:
        volume_type_pk = PrimaryKeyConstraint('volume_type_id',
                                              table=encryptions)
        volume_type_pk.drop()
    except Exception:
        # NOTE (e0ne): SQLite doesn't support 'drop constraint' statament
        if migrate_engine.url.get_dialect().name.startswith('sqlite'):
            pass
        else:
            raise

    pkey = PrimaryKeyConstraint(encryptions.columns.encryption_id)
    pkey.create()


def downgrade(migrate_engine):
    meta = MetaData()
    meta.bind = migrate_engine

    encryptions = Table('encryption', meta, autoload=True)
    encryption_id_pk = PrimaryKeyConstraint(encryptions.columns.encryption_id)

    encryption_id_pk.drop()
    encryptions.drop_column(encryptions.columns.encryption_id)

    volume_type_pk = PrimaryKeyConstraint(encryptions.columns.volume_type_id)
    volume_type_pk.create()

    ref_table = Table('volume_types', meta, autoload=True)
    params = {'columns': [encryptions.c['volume_type_id']],
              'refcolumns': [ref_table.c['id']],
              'name': 'encryption_ibfk_1'}
    volume_type_fk = ForeignKeyConstraint(**params)
    volume_type_fk.create()
