# Copyright 2014 Big Switch Networks, Inc.
# All Rights Reserved.
#
# Copyright 2011 Nicira Networks, Inc.
# 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.
# @author: Kevin Benton, kevin.benton@bigswitch.com

import eventlet
import sys
import time

from oslo.config import cfg

from neutron.agent.linux import ovs_lib
from neutron.agent.linux import utils
from neutron.agent import rpc as agent_rpc
from neutron.agent import securitygroups_rpc as sg_rpc
from neutron.common import config
from neutron.common import topics
from neutron import context as q_context
from neutron.extensions import securitygroup as ext_sg
from neutron.openstack.common import excutils
from neutron.openstack.common import log
from neutron.openstack.common.rpc import dispatcher
from neutron.plugins.bigswitch import config as pl_config

LOG = log.getLogger(__name__)


class IVSBridge(ovs_lib.OVSBridge):
    '''
    This class does not provide parity with OVS using IVS.
    It's only the bare minimum necessary to use IVS with this agent.
    '''
    def run_vsctl(self, args, check_error=False):
        full_args = ["ivs-ctl"] + args
        try:
            return utils.execute(full_args, root_helper=self.root_helper)
        except Exception as e:
            with excutils.save_and_reraise_exception() as ctxt:
                LOG.error(_("Unable to execute %(cmd)s. "
                            "Exception: %(exception)s"),
                          {'cmd': full_args, 'exception': e})
                if not check_error:
                    ctxt.reraise = False

    def get_vif_port_set(self):
        port_names = self.get_port_name_list()
        edge_ports = set(port_names)
        return edge_ports

    def get_vif_port_by_id(self, port_id):
        # IVS in nova uses hybrid method with last 14 chars of UUID
        name = 'qvo%s' % port_id[:14]
        if name in self.get_vif_port_set():
            return name
        return False


class PluginApi(agent_rpc.PluginApi,
                sg_rpc.SecurityGroupServerRpcApiMixin):
    pass


class SecurityGroupAgent(sg_rpc.SecurityGroupAgentRpcMixin):
    def __init__(self, context, plugin_rpc, root_helper):
        self.context = context
        self.plugin_rpc = plugin_rpc
        self.root_helper = root_helper
        self.init_firewall()


class RestProxyAgent(sg_rpc.SecurityGroupAgentRpcCallbackMixin):

    RPC_API_VERSION = '1.1'

    def __init__(self, integ_br, polling_interval, root_helper, vs='ovs'):
        super(RestProxyAgent, self).__init__()
        self.polling_interval = polling_interval
        self._setup_rpc()
        self.sg_agent = SecurityGroupAgent(self.context,
                                           self.plugin_rpc,
                                           root_helper)
        if vs == 'ivs':
            self.int_br = IVSBridge(integ_br, root_helper)
        else:
            self.int_br = ovs_lib.OVSBridge(integ_br, root_helper)

    def _setup_rpc(self):
        self.topic = topics.AGENT
        self.plugin_rpc = PluginApi(topics.PLUGIN)
        self.context = q_context.get_admin_context_without_session()
        self.dispatcher = dispatcher.RpcDispatcher([self])
        consumers = [[topics.PORT, topics.UPDATE],
                     [topics.SECURITY_GROUP, topics.UPDATE]]
        self.connection = agent_rpc.create_consumers(self.dispatcher,
                                                     self.topic,
                                                     consumers)

    def port_update(self, context, **kwargs):
        LOG.debug(_("Port update received"))
        port = kwargs.get('port')
        vif_port = self.int_br.get_vif_port_by_id(port['id'])
        if not vif_port:
            LOG.debug(_("Port %s is not present on this host."), port['id'])
            return

        LOG.debug(_("Port %s found. Refreshing firewall."), port['id'])
        if ext_sg.SECURITYGROUPS in port:
            self.sg_agent.refresh_firewall()

    def _update_ports(self, registered_ports):
        ports = self.int_br.get_vif_port_set()
        if ports == registered_ports:
            return
        added = ports - registered_ports
        removed = registered_ports - ports
        return {'current': ports,
                'added': added,
                'removed': removed}

    def _process_devices_filter(self, port_info):
        if 'added' in port_info:
            self.sg_agent.prepare_devices_filter(port_info['added'])
        if 'removed' in port_info:
            self.sg_agent.remove_devices_filter(port_info['removed'])

    def daemon_loop(self):
        ports = set()

        while True:
            start = time.time()
            try:
                port_info = self._update_ports(ports)
                if port_info:
                    LOG.debug(_("Agent loop has new device"))
                    self._process_devices_filter(port_info)
                    ports = port_info['current']
            except Exception:
                LOG.exception(_("Error in agent event loop"))

            elapsed = max(time.time() - start, 0)
            if (elapsed < self.polling_interval):
                time.sleep(self.polling_interval - elapsed)
            else:
                LOG.debug(_("Loop iteration exceeded interval "
                            "(%(polling_interval)s vs. %(elapsed)s)!"),
                          {'polling_interval': self.polling_interval,
                           'elapsed': elapsed})


def main():
    eventlet.monkey_patch()
    cfg.CONF(project='neutron')
    config.setup_logging(cfg.CONF)
    pl_config.register_config()

    integ_br = cfg.CONF.RESTPROXYAGENT.integration_bridge
    polling_interval = cfg.CONF.RESTPROXYAGENT.polling_interval
    root_helper = cfg.CONF.AGENT.root_helper
    bsnagent = RestProxyAgent(integ_br, polling_interval, root_helper,
                              cfg.CONF.RESTPROXYAGENT.virtual_switch_type)
    bsnagent.daemon_loop()
    sys.exit(0)

if __name__ == "__main__":
    main()