/*
 * Copyright (c) 2014 Contextream, Inc. and others.  All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 which accompanies this distribution,
 * and is available at http://www.eclipse.org/legal/epl-v10.html
 */

package org.opendaylight.lispflowmapping.implementation.lisp;

import java.net.InetAddress;
import java.net.NetworkInterface;
import java.net.SocketException;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.HashSet;
import java.util.List;
import java.util.Objects;
import java.util.Set;

import org.apache.commons.lang3.BooleanUtils;
import org.apache.commons.lang3.exception.ExceptionUtils;
import org.opendaylight.controller.md.sal.binding.api.NotificationService;
import org.opendaylight.lispflowmapping.implementation.authentication.LispAuthenticationUtil;
import org.opendaylight.lispflowmapping.implementation.config.ConfigIni;
import org.opendaylight.lispflowmapping.interfaces.dao.SubKeys;
import org.opendaylight.lispflowmapping.interfaces.dao.SubscriberRLOC;
import org.opendaylight.lispflowmapping.interfaces.lisp.IMapNotifyHandler;
import org.opendaylight.lispflowmapping.interfaces.lisp.IMapServerAsync;
import org.opendaylight.lispflowmapping.interfaces.mappingservice.IMappingService;
import org.opendaylight.lispflowmapping.lisp.type.LispMessage;
import org.opendaylight.lispflowmapping.lisp.util.LispAddressStringifier;
import org.opendaylight.lispflowmapping.lisp.util.LispAddressUtil;
import org.opendaylight.lispflowmapping.lisp.util.MapNotifyBuilderHelper;
import org.opendaylight.lispflowmapping.lisp.util.MapRequestUtil;
import org.opendaylight.lispflowmapping.lisp.util.SourceDestKeyHelper;
import org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.inet.types.rev100924.IpAddress;
import org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.inet.types.rev100924.PortNumber;
import org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.lisp.address.types.rev151105.lisp.address.address.SourceDestKey;
import org.opendaylight.yang.gen.v1.urn.opendaylight.lfm.lisp.proto.rev151105.MapRegister;
import org.opendaylight.yang.gen.v1.urn.opendaylight.lfm.lisp.proto.rev151105.SiteId;
import org.opendaylight.yang.gen.v1.urn.opendaylight.lfm.lisp.proto.rev151105.eid.container.Eid;
import org.opendaylight.yang.gen.v1.urn.opendaylight.lfm.lisp.proto.rev151105.eid.list.EidItem;
import org.opendaylight.yang.gen.v1.urn.opendaylight.lfm.lisp.proto.rev151105.eid.list.EidItemBuilder;
import org.opendaylight.yang.gen.v1.urn.opendaylight.lfm.lisp.proto.rev151105.mapnotifymessage.MapNotifyBuilder;
import org.opendaylight.yang.gen.v1.urn.opendaylight.lfm.lisp.proto.rev151105.mapping.record.container.MappingRecord;
import org.opendaylight.yang.gen.v1.urn.opendaylight.lfm.lisp.proto.rev151105.mapping.record.container.MappingRecordBuilder;
import org.opendaylight.yang.gen.v1.urn.opendaylight.lfm.lisp.proto.rev151105.mapping.record.list.MappingRecordItem;
import org.opendaylight.yang.gen.v1.urn.opendaylight.lfm.lisp.proto.rev151105.mapping.record.list.MappingRecordItemBuilder;
import org.opendaylight.yang.gen.v1.urn.opendaylight.lfm.lisp.proto.rev151105.maprequestnotification.MapRequestBuilder;
import org.opendaylight.yang.gen.v1.urn.opendaylight.lfm.lisp.proto.rev151105.transport.address.TransportAddress;
import org.opendaylight.yang.gen.v1.urn.opendaylight.lfm.lisp.proto.rev151105.transport.address.TransportAddressBuilder;
import org.opendaylight.yang.gen.v1.urn.opendaylight.lfm.mappingservice.rev150906.MappingChange;
import org.opendaylight.yang.gen.v1.urn.opendaylight.lfm.mappingservice.rev150906.MappingChanged;
import org.opendaylight.yang.gen.v1.urn.opendaylight.lfm.mappingservice.rev150906.MappingOrigin;
import org.opendaylight.yang.gen.v1.urn.opendaylight.lfm.mappingservice.rev150906.OdlMappingserviceListener;
import org.opendaylight.yang.gen.v1.urn.opendaylight.lfm.mappingservice.rev150906.mapping.authkey.container.MappingAuthkey;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.google.common.base.Preconditions;

public class MapServer implements IMapServerAsync, OdlMappingserviceListener {

    protected static final Logger LOG = LoggerFactory.getLogger(MapServer.class);
    private IMappingService mapService;
    private boolean authenticate;
    private boolean subscriptionService;
    private IMapNotifyHandler notifyHandler;
    private NotificationService notificationService;

    public MapServer(IMappingService mapService, boolean authenticate, boolean subscriptionService,
            IMapNotifyHandler notifyHandler, NotificationService notificationService) {
        Preconditions.checkNotNull(mapService);
        this.mapService = mapService;
        this.authenticate = authenticate;
        this.subscriptionService = subscriptionService;
        this.notifyHandler = notifyHandler;
        this.notificationService = notificationService;
        if (notificationService != null) {
            notificationService.registerNotificationListener(this);
        }
    }

    @Override
    public void setSubscriptionService(boolean subscriptionService) {
        this.subscriptionService = subscriptionService;
    }

    @Override
    public boolean shouldAuthenticate() {
        return authenticate;
    }

    @Override
    public void setShouldAuthenticate(boolean shouldAuthenticate) {
        authenticate = shouldAuthenticate;
    }

    @SuppressWarnings("unchecked")
    public void handleMapRegister(MapRegister mapRegister) {
        boolean authFailed = false;
        boolean mappingUpdated = false;
        String password = null;
        Set<SubscriberRLOC> subscribers = null;
        MappingRecord oldMapping;

        for (MappingRecordItem record : mapRegister.getMappingRecordItem()) {
            MappingRecord mapping = record.getMappingRecord();
            if (authenticate) {
                MappingAuthkey authkey = mapService.getAuthenticationKey(mapping.getEid());
                if (authkey != null) {
                    password = authkey.getKeyString();
                }
                if (!LispAuthenticationUtil.validate(mapRegister, password)) {
                    LOG.warn("Authentication failed");
                    authFailed = true;
                    break;
                }
            }

            oldMapping = (MappingRecord) mapService.getMapping(MappingOrigin.Southbound, mapping.getEid());
            mapService.addMapping(MappingOrigin.Southbound, mapping.getEid(), getSiteId(mapRegister), mapping);

            if (subscriptionService) {
                MappingRecord newMapping = ConfigIni.getInstance().mappingMergeIsSet() ?
                        (MappingRecord) mapService.getMapping(MappingOrigin.Southbound, mapping.getEid()) : mapping;

                if (mappingChanged(oldMapping, newMapping)) {
                    if (LOG.isDebugEnabled()) {
                        LOG.debug("Mapping update occured for {} SMRs will be sent for its subscribers.",
                                LispAddressStringifier.getString(mapping.getEid()));
                    }
                    subscribers = getSubscribers(mapping.getEid());
                    sendSmrs(mapping, subscribers);
                    mappingUpdated = true;
                }
            }
        }
        if (!authFailed && BooleanUtils.isTrue(mapRegister.isWantMapNotify())) {
            LOG.trace("MapRegister wants MapNotify");
            MapNotifyBuilder builder = new MapNotifyBuilder();
            List<TransportAddress> rlocs = null;
            if (ConfigIni.getInstance().mappingMergeIsSet()) {
                Set<IpAddress> notifyRlocs = new HashSet<IpAddress>();
                List<MappingRecordItem> mergedMappings = new ArrayList<MappingRecordItem>();
                for (MappingRecordItem record : mapRegister.getMappingRecordItem()) {
                    MappingRecord mapping = record.getMappingRecord();
                    MappingRecord currentRecord = (MappingRecord) mapService.getMapping(MappingOrigin.Southbound,
                            mapping.getEid());
                    mergedMappings.add(new MappingRecordItemBuilder().setMappingRecord(currentRecord).build());
                    Set<IpAddress> sourceRlocs = (Set<IpAddress>) mapService.getData(MappingOrigin.Southbound,
                            mapping.getEid(), SubKeys.SRC_RLOCS);
                    if (sourceRlocs != null) {
                        notifyRlocs.addAll(sourceRlocs);
                    }
                }
                MapNotifyBuilderHelper.setFromMapRegisterAndMappingRecordItems(builder, mapRegister, mergedMappings);
                // send map-notify to merge group only when mapping record is changed
                if (mappingUpdated) {
                    rlocs = getTransportAddresses(notifyRlocs);
                }
            } else {
                MapNotifyBuilderHelper.setFromMapRegister(builder, mapRegister);
            }
            if (authenticate) {
                builder.setAuthenticationData(LispAuthenticationUtil.createAuthenticationData(builder.build(),
                        password));
            }
            notifyHandler.handleMapNotify(builder.build(), rlocs);
        }
    }

    private static List<TransportAddress> getTransportAddresses(Set<IpAddress> addresses) {
        List<TransportAddress> rlocs = new ArrayList<TransportAddress>();
        for (IpAddress address : addresses) {
            TransportAddressBuilder tab = new TransportAddressBuilder();
            tab.setIpAddress(address);
            tab.setPort(new PortNumber(LispMessage.PORT_NUM));
            rlocs.add(tab.build());
        }
        return rlocs;
    }

    private SiteId getSiteId(MapRegister mapRegister) {
        return (mapRegister.getSiteId() != null) ? new SiteId(mapRegister.getSiteId()) : null;
    }

    @Override
    public void onMappingChanged(MappingChanged notification) {
        if (subscriptionService) {
            sendSmrs(notification.getMappingRecord(), getSubscribers(notification.getMappingRecord().getEid()));
            if (notification.getChangeType().equals(MappingChange.Removed)) {
                removeSubscribers(notification.getMappingRecord().getEid());
            }
        }
    }

    private static boolean mappingChanged(MappingRecord oldMapping, MappingRecord newMapping) {
        // We only check for fields we care about
        // XXX: This code needs to be checked and updated when the YANG model is modified
        Preconditions.checkNotNull(newMapping, "The new mapping should never be null");
        if (oldMapping == null) {
            LOG.trace("mappingChanged(): old mapping is null");
            return true;
        } else if (!Objects.equals(oldMapping.getEid(), newMapping.getEid())) {
            LOG.trace("mappingChanged(): EID");
            return true;
        } else if (!Objects.equals(oldMapping.getLocatorRecord(), newMapping.getLocatorRecord())) {
            LOG.trace("mappingChanged(): RLOC");
            return true;
        } else if (!Objects.equals(oldMapping.getAction(), newMapping.getAction())) {
            LOG.trace("mappingChanged(): action");
            return true;
        } else if (!Objects.equals(oldMapping.getRecordTtl(), newMapping.getRecordTtl())) {
            LOG.trace("mappingChanged(): TTL");
            return true;
        } else if (!Objects.equals(oldMapping.getMapVersion(), newMapping.getMapVersion())) {
            LOG.trace("mappingChanged(): mapping version");
            return true;
        }
        return false;
    }

    private void sendSmrs(MappingRecord record, Set<SubscriberRLOC> subscribers) {
        Eid eid = record.getEid();
        handleSmr(eid, subscribers, notifyHandler);

        // For SrcDst LCAF also send SMRs to Dst prefix
        if (eid.getAddress() instanceof SourceDestKey) {
            Eid dstAddr = SourceDestKeyHelper.getDst(eid);
            Set<SubscriberRLOC> dstSubs = getSubscribers(dstAddr);
            MappingRecord newRecord = new MappingRecordBuilder(record).setEid(dstAddr).build();
            handleSmr(newRecord.getEid(), dstSubs, notifyHandler);
        }
    }

    private void handleSmr(Eid eid, Set<SubscriberRLOC> subscribers, IMapNotifyHandler callback) {
        if (subscribers == null) {
            return;
        }
        MapRequestBuilder mrb = MapRequestUtil.prepareSMR(eid, LispAddressUtil.toRloc(getLocalAddress()));
        LOG.trace("Built SMR packet: " + mrb.build().toString());
        for (SubscriberRLOC subscriber : subscribers) {
            if (subscriber.timedOut()) {
                LOG.trace("Lazy removing expired subscriber entry " + subscriber.toString());
                subscribers.remove(subscriber);
            } else {
                try {
                    // The address stored in the SMR's EID record is used as Source EID in the SMR-invoked Map-Request.
                    // To ensure consistent behavior it is set to the value used to originally request a given mapping
                    mrb.setEidItem(new ArrayList<EidItem>());
                    mrb.getEidItem().add(new EidItemBuilder().setEid(subscriber.getSrcEid()).build());
                    callback.handleSMR(mrb.build(), subscriber.getSrcRloc());
                } catch (Exception e) {
                    LOG.error("Errors encountered while handling SMR:" + ExceptionUtils.getStackTrace(e));
                }
            }
        }
        addSubscribers(eid, subscribers);
    }

    @SuppressWarnings("unchecked")
    private Set<SubscriberRLOC> getSubscribers(Eid address) {
        return (Set<SubscriberRLOC>) mapService.getData(MappingOrigin.Southbound, address, SubKeys.SUBSCRIBERS);
    }

    private void removeSubscribers(Eid address) {
        mapService.removeData(MappingOrigin.Southbound, address, SubKeys.SUBSCRIBERS);
    }

    private void addSubscribers(Eid address, Set<SubscriberRLOC> subscribers) {
        mapService.addData(MappingOrigin.Southbound, address, SubKeys.SUBSCRIBERS, subscribers);
    }

    private static InetAddress getLocalAddress() {
        try {
            Enumeration<NetworkInterface> interfaces = NetworkInterface.getNetworkInterfaces();
            while (interfaces.hasMoreElements()) {
                NetworkInterface current = interfaces.nextElement();
                LOG.debug("Interface " + current.toString());
                if (!current.isUp() || current.isLoopback() || current.isVirtual()) {
                    continue;
                }
                Enumeration<InetAddress> addresses = current.getInetAddresses();
                while (addresses.hasMoreElements()) {
                    InetAddress current_addr = addresses.nextElement();
                    // Skip loopback and link local addresses
                    if (current_addr.isLoopbackAddress() || current_addr.isLinkLocalAddress()) {
                        continue;
                    }
                    LOG.debug(current_addr.getHostAddress());
                    return current_addr;
                }
            }
        } catch (SocketException se) {
            LOG.debug("Caught socket exceptio", se);
        }
        return null;
    }
}