# Copyright (c) 2013 Rackspace, 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.

from oslo_log import log
from stevedore import driver

from zaqar.api import handler
from zaqar.common import cache as oslo_cache
from zaqar.common import configs
from zaqar.common import consts
from zaqar.common import decorators
from zaqar.common import errors
from zaqar.storage import pipeline
from zaqar.storage import pooling
from zaqar.storage import utils as storage_utils
from zaqar.transport import base
from zaqar.transport import validation

from zaqar.i18n import _LE

LOG = log.getLogger(__name__)


class Bootstrap(object):
    """Defines the Zaqar bootstrapper.

    The bootstrap loads up drivers per a given configuration, and
    manages their lifetimes.
    """

    def __init__(self, conf):
        self.conf = conf

        for group, opts in configs._config_options():
            self.conf.register_opts(opts, group=group)

        self.driver_conf = self.conf[configs._DRIVER_GROUP]

    @decorators.lazy_property(write=False)
    def api(self):
        LOG.debug(u'Loading API handler')
        validate = validation.Validator(self.conf)
        defaults = base.ResourceDefaults(self.conf)
        return handler.Handler(self.storage, self.control, validate, defaults)

    @decorators.lazy_property(write=False)
    def storage(self):
        LOG.debug(u'Loading storage driver')
        if self.conf.pooling:
            LOG.debug(u'Storage pooling enabled')
            storage_driver = pooling.DataDriver(self.conf, self.cache,
                                                self.control)
        else:
            storage_driver = storage_utils.load_storage_driver(
                self.conf, self.cache, control_driver=self.control)

        LOG.debug(u'Loading storage pipeline')
        return pipeline.DataDriver(self.conf, storage_driver,
                                   self.control)

    @decorators.lazy_property(write=False)
    def control(self):
        LOG.debug(u'Loading storage control driver')
        return storage_utils.load_storage_driver(self.conf, self.cache,
                                                 control_mode=True)

    @decorators.lazy_property(write=False)
    def cache(self):
        LOG.debug(u'Loading proxy cache driver')
        try:
            oslo_cache.register_config(self.conf)
            return oslo_cache.get_cache(self.conf)
        except RuntimeError as exc:
            LOG.exception(exc)
            raise errors.InvalidDriver(exc)

    @decorators.lazy_property(write=False)
    def transport(self):
        transport_name = self.driver_conf.transport
        LOG.debug(u'Loading transport driver: %s', transport_name)

        if transport_name == consts.TRANSPORT_WEBSOCKET:
            args = [self.conf, self.api, self.cache]
        else:
            args = [
                self.conf,
                self.storage,
                self.cache,
                self.control,
            ]

        try:
            mgr = driver.DriverManager('zaqar.transport',
                                       transport_name,
                                       invoke_on_load=True,
                                       invoke_args=args)
            return mgr.driver
        except RuntimeError as exc:
            LOG.exception(exc)
            LOG.error(_LE(u'Failed to load transport driver zaqar.transport.'
                          u'%(driver)s with args %(args)s'),
                      {'driver': transport_name, 'args': args})
            raise errors.InvalidDriver(exc)

    def run(self):
        self.transport.listen()
