#    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 neutron_lib import constants
from oslo_log import log as logging

from neutron.agent.l3 import namespaces
from neutron.agent.linux import ip_lib

LOG = logging.getLogger(__name__)
SNAT_NS_PREFIX = 'snat-'


class SnatNamespace(namespaces.Namespace):

    def __init__(self, router_id, agent_conf, driver, use_ipv6):
        self.router_id = router_id
        name = self.get_snat_ns_name(router_id)
        super(SnatNamespace, self).__init__(
            name, agent_conf, driver, use_ipv6)

    def create(self):
        super(SnatNamespace, self).create()
        # This might be an HA router namespaces and it should not have
        # ip_nonlocal_bind enabled
        ip_lib.set_ip_nonlocal_bind_for_namespace(self.name, 0)
        # Set nf_conntrack_tcp_loose to 0 to ensure mid-stream
        # TCP conversations aren't taken over by SNAT
        cmd = ['net.netfilter.nf_conntrack_tcp_loose=0']
        ip_lib.sysctl(cmd, namespace=self.name)

    @classmethod
    def get_snat_ns_name(cls, router_id):
        return namespaces.build_ns_name(SNAT_NS_PREFIX, router_id)

    @namespaces.check_ns_existence
    def delete(self):
        ns_ip = ip_lib.IPWrapper(namespace=self.name)
        for d in ns_ip.get_devices():
            if d.name.startswith(constants.SNAT_INT_DEV_PREFIX):
                LOG.debug('Unplugging DVR device %s', d.name)
                self.driver.unplug(d.name, namespace=self.name,
                                   prefix=constants.SNAT_INT_DEV_PREFIX)
            elif d.name.startswith(namespaces.EXTERNAL_DEV_PREFIX):
                self.driver.unplug(
                    d.name,
                    bridge=self.agent_conf.external_network_bridge,
                    namespace=self.name,
                    prefix=namespaces.EXTERNAL_DEV_PREFIX)

        # TODO(mrsmith): delete ext-gw-port
        LOG.debug('DVR: destroy snat ns: %s', self.name)
        super(SnatNamespace, self).delete()
