/*
 * Copyright 2016 Open Networking Laboratory
 *
 * 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.
 */

package org.onosproject.routing.impl;

import org.apache.felix.scr.annotations.Activate;
import org.apache.felix.scr.annotations.Component;
import org.apache.felix.scr.annotations.Deactivate;
import org.apache.felix.scr.annotations.Reference;
import org.apache.felix.scr.annotations.ReferenceCardinality;
import org.onlab.packet.EthType;
import org.onosproject.core.ApplicationId;
import org.onosproject.core.CoreService;
import org.onosproject.incubator.net.intf.Interface;
import org.onosproject.incubator.net.intf.InterfaceService;
import org.onosproject.net.ConnectPoint;
import org.onosproject.net.DeviceId;
import org.onosproject.net.PortNumber;
import org.onosproject.net.config.NetworkConfigEvent;
import org.onosproject.net.config.NetworkConfigListener;
import org.onosproject.net.config.NetworkConfigService;
import org.onosproject.net.device.DeviceEvent;
import org.onosproject.net.device.DeviceListener;
import org.onosproject.net.device.DeviceService;
import org.onosproject.net.flow.DefaultTrafficSelector;
import org.onosproject.net.flow.DefaultTrafficTreatment;
import org.onosproject.net.flow.TrafficSelector;
import org.onosproject.net.flow.TrafficTreatment;
import org.onosproject.net.flowobjective.DefaultForwardingObjective;
import org.onosproject.net.flowobjective.FlowObjectiveService;
import org.onosproject.net.flowobjective.ForwardingObjective;
import org.onosproject.net.host.InterfaceIpAddress;
import org.onosproject.routing.RoutingService;
import org.onosproject.routing.config.RouterConfig;
import org.slf4j.Logger;

import static org.slf4j.LoggerFactory.getLogger;

/**
 * Manages connectivity between peers redirecting control traffic to a routing
 * control plane available on the dataplane.
 */
@Component(immediate = true, enabled = false)
public class ControlPlaneRedirectManager {

    private final Logger log = getLogger(getClass());

    private static final int PRIORITY = 40001;
    private static final int OSPF_IP_PROTO = 0x59;

    private static final String APP_NAME = "org.onosproject.cpredirect";
    private ApplicationId appId;

    private ConnectPoint controlPlaneConnectPoint;
    private boolean ospfEnabled = false;

    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
    protected CoreService coreService;

    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
    protected DeviceService deviceService;

    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
    protected InterfaceService interfaceService;

    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
    protected FlowObjectiveService flowObjectiveService;

    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
    protected NetworkConfigService networkConfigService;

    private final InternalDeviceListener deviceListener = new InternalDeviceListener();
    private final InternalNetworkConfigListener networkConfigListener =
            new InternalNetworkConfigListener();

    @Activate
    public void activate() {
        this.appId = coreService.registerApplication(APP_NAME);

        deviceService.addListener(deviceListener);
        networkConfigService.addListener(networkConfigListener);

        updateConfig();
    }

    @Deactivate
    public void deactivate() {
        deviceService.removeListener(deviceListener);
        networkConfigService.removeListener(networkConfigListener);
    }

    private void updateConfig() {
        ApplicationId routingAppId =
                coreService.registerApplication(RoutingService.ROUTER_APP_ID);

        RouterConfig config = networkConfigService.getConfig(
                routingAppId, RoutingService.ROUTER_CONFIG_CLASS);

        if (config == null) {
            log.info("Router config not available");
            return;
        }

        controlPlaneConnectPoint = config.getControlPlaneConnectPoint();
        ospfEnabled = config.getOspfEnabled();

        updateDevice();
    }

    private void updateDevice() {
        if (controlPlaneConnectPoint != null &&
                deviceService.isAvailable(controlPlaneConnectPoint.deviceId())) {
            DeviceId deviceId = controlPlaneConnectPoint.deviceId();

            interfaceService.getInterfaces().stream()
                    .filter(intf -> intf.connectPoint().deviceId().equals(deviceId))
                    .forEach(this::provisionInterface);

            log.info("Set up interfaces on {}", controlPlaneConnectPoint.deviceId());
        }
    }

    private void provisionInterface(Interface intf) {
        addBasicInterfaceForwarding(intf);
        updateOspfForwarding(intf);
    }

    private void addBasicInterfaceForwarding(Interface intf) {
        log.debug("Adding interface objectives for {}", intf);

        DeviceId deviceId = controlPlaneConnectPoint.deviceId();
        PortNumber controlPlanePort = controlPlaneConnectPoint.port();

        for (InterfaceIpAddress ip : intf.ipAddresses()) {
            // IPv4 to router
            TrafficSelector toSelector = DefaultTrafficSelector.builder()
                    .matchInPort(intf.connectPoint().port())
                    .matchEthDst(intf.mac())
                    .matchEthType(EthType.EtherType.IPV4.ethType().toShort())
                    .matchVlanId(intf.vlan())
                    .matchIPDst(ip.ipAddress().toIpPrefix())
                    .build();

            TrafficTreatment toTreatment = DefaultTrafficTreatment.builder()
                    .setOutput(controlPlanePort)
                    .build();

            flowObjectiveService.forward(deviceId,
                    buildForwardingObjective(toSelector, toTreatment, true));

            // IPv4 from router
            TrafficSelector fromSelector = DefaultTrafficSelector.builder()
                    .matchInPort(controlPlanePort)
                    .matchEthSrc(intf.mac())
                    .matchVlanId(intf.vlan())
                    .matchEthType(EthType.EtherType.IPV4.ethType().toShort())
                    .matchIPSrc(ip.ipAddress().toIpPrefix())
                    .build();

            TrafficTreatment intfTreatment = DefaultTrafficTreatment.builder()
                    .setOutput(intf.connectPoint().port())
                    .build();

            flowObjectiveService.forward(deviceId,
                    buildForwardingObjective(fromSelector, intfTreatment, true));

            // ARP to router
            toSelector = DefaultTrafficSelector.builder()
                    .matchInPort(intf.connectPoint().port())
                    .matchEthType(EthType.EtherType.ARP.ethType().toShort())
                    .matchVlanId(intf.vlan())
                    .build();

            toTreatment = DefaultTrafficTreatment.builder()
                    .setOutput(controlPlanePort)
                    .punt()
                    .build();

            flowObjectiveService.forward(deviceId,
                    buildForwardingObjective(toSelector, toTreatment, true));

            // ARP from router
            fromSelector = DefaultTrafficSelector.builder()
                    .matchInPort(controlPlanePort)
                    .matchEthSrc(intf.mac())
                    .matchVlanId(intf.vlan())
                    .matchEthType(EthType.EtherType.ARP.ethType().toShort())
                    .build();

            intfTreatment = DefaultTrafficTreatment.builder()
                    .setOutput(intf.connectPoint().port())
                    .punt()
                    .build();

            flowObjectiveService.forward(deviceId,
                    buildForwardingObjective(fromSelector, intfTreatment, true));
        }
    }

    private void updateOspfForwarding(Interface intf) {
        // OSPF to router
        TrafficSelector toSelector = DefaultTrafficSelector.builder()
                .matchInPort(intf.connectPoint().port())
                .matchEthType(EthType.EtherType.IPV4.ethType().toShort())
                .matchVlanId(intf.vlan())
                .matchIPProtocol((byte) OSPF_IP_PROTO)
                .build();

        TrafficTreatment toTreatment = DefaultTrafficTreatment.builder()
                .setOutput(controlPlaneConnectPoint.port())
                .build();

        flowObjectiveService.forward(controlPlaneConnectPoint.deviceId(),
                buildForwardingObjective(toSelector, toTreatment, ospfEnabled));
    }

    /**
     * Builds a forwarding objective from the given selector and treatment.
     *
     * @param selector selector
     * @param treatment treatment
     * @param add true to create an add objective, false to create a remove
     *            objective
     * @return forwarding objective
     */
    private ForwardingObjective buildForwardingObjective(TrafficSelector selector,
                                                         TrafficTreatment treatment,
                                                         boolean add) {

        ForwardingObjective.Builder fobBuilder = DefaultForwardingObjective.builder()
                .withSelector(selector)
                .withTreatment(treatment)
                .fromApp(appId)
                .withPriority(PRIORITY)
                .withFlag(ForwardingObjective.Flag.VERSATILE);

        return add ? fobBuilder.add() : fobBuilder.remove();
    }

    /**
     * Listener for device events.
     */
    private class InternalDeviceListener implements DeviceListener {
        @Override
        public void event(DeviceEvent event) {
            if (controlPlaneConnectPoint != null &&
                    event.subject().id().equals(controlPlaneConnectPoint.deviceId())) {
                switch (event.type()) {
                case DEVICE_ADDED:
                case DEVICE_AVAILABILITY_CHANGED:
                    if (deviceService.isAvailable(event.subject().id())) {
                        log.info("Device connected {}", event.subject().id());
                        updateDevice();
                    }

                    break;
                case DEVICE_UPDATED:
                case DEVICE_REMOVED:
                case DEVICE_SUSPENDED:
                case PORT_ADDED:
                case PORT_UPDATED:
                case PORT_REMOVED:
                default:
                    break;
                }
            }
        }
    }

    /**
     * Listener for network config events.
     */
    private class InternalNetworkConfigListener implements NetworkConfigListener {
        @Override
        public void event(NetworkConfigEvent event) {
            if (event.configClass().equals(RoutingService.ROUTER_CONFIG_CLASS)) {
                switch (event.type()) {
                case CONFIG_ADDED:
                case CONFIG_UPDATED:
                    updateConfig();
                    break;
                case CONFIG_REGISTERED:
                case CONFIG_UNREGISTERED:
                case CONFIG_REMOVED:
                default:
                    break;
                }
            }
        }
    }
}