# Copyright (c) 2013 Huawei Technologies Co., Ltd.
# Copyright (c) 2012 OpenStack Foundation
# All Rights Reserved.
#
#    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.
"""
Provide a unified driver class for users.

The product type and the protocol should be specified in config file before.
"""

from oslo.config import cfg

from cinder import exception
from cinder.openstack.common import log as logging
from cinder.volume.drivers.huawei import huawei_dorado
from cinder.volume.drivers.huawei import huawei_hvs
from cinder.volume.drivers.huawei import huawei_t
from cinder.volume.drivers.huawei import huawei_utils

LOG = logging.getLogger(__name__)

huawei_opt = [
    cfg.StrOpt('cinder_huawei_conf_file',
               default='/etc/cinder/cinder_huawei_conf.xml',
               help='The configuration file for the Cinder Huawei '
                    'driver')]

CONF = cfg.CONF
CONF.register_opts(huawei_opt)


class HuaweiVolumeDriver(object):
    """Define an unified driver for Huawei drivers."""

    def __init__(self, *args, **kwargs):
        super(HuaweiVolumeDriver, self).__init__()
        self._product = {'T': huawei_t, 'Dorado': huawei_dorado,
                         'HVS': huawei_hvs}
        self._protocol = {'iSCSI': 'ISCSIDriver', 'FC': 'FCDriver'}

        self.driver = self._instantiate_driver(*args, **kwargs)

    def _instantiate_driver(self, *args, **kwargs):
        """Instantiate the specified driver."""
        self.configuration = kwargs.get('configuration', None)
        if not self.configuration:
            msg = (_('_instantiate_driver: configuration not found.'))
            raise exception.InvalidInput(reason=msg)

        self.configuration.append_config_values(huawei_opt)
        conf_file = self.configuration.cinder_huawei_conf_file
        (product, protocol) = self._get_conf_info(conf_file)

        LOG.debug('_instantiate_driver: Loading %(protocol)s driver for '
                  'Huawei OceanStor %(product)s series storage arrays.'
                  % {'protocol': protocol,
                     'product': product})

        driver_module = self._product[product]
        driver_class = 'Huawei' + product + self._protocol[protocol]

        driver_class = getattr(driver_module, driver_class)
        return driver_class(*args, **kwargs)

    def _get_conf_info(self, filename):
        """Get product type and connection protocol from config file."""
        root = huawei_utils.parse_xml_file(filename)
        product = root.findtext('Storage/Product').strip()
        protocol = root.findtext('Storage/Protocol').strip()
        if (product in self._product.keys() and
                protocol in self._protocol.keys()):
            return (product, protocol)
        else:
            msg = (_('"Product" or "Protocol" is illegal. "Product" should '
                     'be set to either T, Dorado or HVS. "Protocol" should '
                     'be set to either iSCSI or FC. Product: %(product)s '
                     'Protocol: %(protocol)s')
                   % {'product': product,
                      'protocol': protocol})
            raise exception.InvalidInput(reason=msg)

    def __setattr__(self, name, value):
        """Set the attribute."""
        if getattr(self, 'driver', None):
            self.driver.__setattr__(name, value)
            return
        object.__setattr__(self, name, value)

    def __getattr__(self, name):
        """"Get the attribute."""
        drver = object.__getattribute__(self, 'driver')
        return getattr(drver, name)