# Copyright (C) 2013 Nippon Telegraph and Telephone Corporation.
#
# 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.

import struct

from ryu.base import app_manager
from ryu.controller.handler import MAIN_DISPATCHER
from ryu.controller.handler import set_ev_cls
from ryu.ofproto import ofproto_v1_0
from ryu.lib import addrconv
from ryu.lib import lacplib
from ryu.lib.dpid import str_to_dpid


class SimpleSwitchLacp(app_manager.RyuApp):
    OFP_VERSIONS = [ofproto_v1_0.OFP_VERSION]
    _CONTEXTS = {'lacplib': lacplib.LacpLib}

    def __init__(self, *args, **kwargs):
        super(SimpleSwitchLacp, self).__init__(*args, **kwargs)
        self.mac_to_port = {}
        self._lacp = kwargs['lacplib']
        # in this sample application, bonding i/fs of the switchs
        # shall be set up as follows:
        # - the port 1 and 2 of the datapath 1 face the slave i/fs.
        # - the port 3, 4 and 5 of the datapath 1 face the others.
        # - the port 1 and 2 of the datapath 2 face the others.
        self._lacp.add(
            dpid=str_to_dpid('0000000000000001'), ports=[1, 2])
        self._lacp.add(
            dpid=str_to_dpid('0000000000000001'), ports=[3, 4, 5])
        self._lacp.add(
            dpid=str_to_dpid('0000000000000002'), ports=[1, 2])

    def add_flow(self, datapath, in_port, dst, actions):
        ofproto = datapath.ofproto
        parser = datapath.ofproto_parser

        match = parser.OFPMatch(in_port=in_port,
                                dl_dst=addrconv.mac.text_to_bin(dst))
        mod = parser.OFPFlowMod(
            datapath=datapath, match=match, cookie=0,
            command=ofproto.OFPFC_ADD, actions=actions)
        datapath.send_msg(mod)

    def del_flow(self, datapath, dst):
        ofproto = datapath.ofproto
        parser = datapath.ofproto_parser

        match = parser.OFPMatch(dl_dst=addrconv.mac.text_to_bin(dst))
        mod = parser.OFPFlowMod(
            datapath=datapath, match=match, cookie=0,
            command=ofproto.OFPFC_DELETE)
        datapath.send_msg(mod)

    @set_ev_cls(lacplib.EventPacketIn, MAIN_DISPATCHER)
    def _packet_in_handler(self, ev):
        msg = ev.msg
        datapath = msg.datapath
        ofproto = datapath.ofproto

        (dst_, src_, _eth_type) = struct.unpack_from(
            '!6s6sH', buffer(msg.data), 0)
        src = addrconv.mac.bin_to_text(src_)
        dst = addrconv.mac.bin_to_text(dst_)

        dpid = datapath.id
        self.mac_to_port.setdefault(dpid, {})

        self.logger.info("packet in %s %s %s %s",
                         dpid, src, dst, msg.in_port)

        # learn a mac address to avoid FLOOD next time.
        self.mac_to_port[dpid][src] = msg.in_port

        if dst in self.mac_to_port[dpid]:
            out_port = self.mac_to_port[dpid][dst]
        else:
            out_port = ofproto.OFPP_FLOOD

        actions = [datapath.ofproto_parser.OFPActionOutput(out_port)]

        # install a flow to avoid packet_in next time
        if out_port != ofproto.OFPP_FLOOD:
            self.add_flow(datapath, msg.in_port, dst, actions)

        out = datapath.ofproto_parser.OFPPacketOut(
            datapath=datapath, buffer_id=msg.buffer_id, in_port=msg.in_port,
            actions=actions)
        datapath.send_msg(out)

    @set_ev_cls(lacplib.EventSlaveStateChanged, MAIN_DISPATCHER)
    def _slave_state_changed_handler(self, ev):
        datapath = ev.datapath
        dpid = datapath.id
        port_no = ev.port
        enabled = ev.enabled
        self.logger.info("slave state changed port: %d enabled: %s",
                         port_no, enabled)
        if dpid in self.mac_to_port:
            for mac in self.mac_to_port[dpid]:
                self.del_flow(datapath, mac)
            del self.mac_to_port[dpid]
        self.mac_to_port.setdefault(dpid, {})