# Copyright (c) 2013 Mirantis Inc.
#
# 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.
#
# Based on Neutron's migration/cli.py

from __future__ import with_statement
from logging import config as c

from alembic import context
from sqlalchemy import create_engine
from sqlalchemy import pool

from distil.db.sqlalchemy import model_base
from oslo_utils import importutils


importutils.import_module('distil.db.sqlalchemy.models')

# this is the Alembic Config object, which provides
# access to the values within the .ini file in use.
config = context.config
distil_config = config.distil_config

# Interpret the config file for Python logging.
# This line sets up loggers basically.
c.fileConfig(config.config_file_name)

# add your model's MetaData object here
# for 'autogenerate' support
# from myapp import mymodel
# target_metadata = mymodel.Base.metadata
target_metadata = model_base.DistilBase.metadata

# other values from the config, defined by the needs of env.py,
# can be acquired:
# my_important_option = config.get_main_option("my_important_option")
# ... etc.


def run_migrations_offline():
    """Run migrations in 'offline' mode.

    This configures the context with just a URL
    and not an Engine, though an Engine is acceptable
    here as well.  By skipping the Engine creation
    we don't even need a DBAPI to be available.

    Calls to context.execute() here emit the given string to the
    script output.

    """
    context.configure(url=distil_config.database.connection)

    with context.begin_transaction():
        context.run_migrations()


def run_migrations_online():
    """Run migrations in 'online' mode.

    In this scenario we need to create an Engine
    and associate a connection with the context.

    """
    engine = create_engine(
        distil_config.database.connection,
        poolclass=pool.NullPool)

    connection = engine.connect()
    context.configure(
        connection=connection,
        target_metadata=target_metadata)

    try:
        with context.begin_transaction():
            context.run_migrations()
    finally:
        connection.close()


if context.is_offline_mode():
    run_migrations_offline()
else:
    run_migrations_online()