/*
 * Copyright (c) 2015 Cisco Systems, 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.protocol.bgp.rib.spi;

import static java.util.Objects.requireNonNull;

import com.google.common.annotations.Beta;
import com.google.common.base.Optional;
import java.util.Collection;
import java.util.Collections;
import javax.annotation.Nonnull;
import org.opendaylight.controller.md.sal.common.api.data.LogicalDatastoreType;
import org.opendaylight.controller.md.sal.dom.api.DOMDataWriteTransaction;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.message.rev171207.Update;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.message.rev171207.UpdateBuilder;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.message.rev171207.path.attributes.Attributes;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.message.rev171207.path.attributes.AttributesBuilder;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.multiprotocol.rev171207.Attributes1;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.multiprotocol.rev171207.Attributes1Builder;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.multiprotocol.rev171207.Attributes2;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.multiprotocol.rev171207.Attributes2Builder;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.multiprotocol.rev171207.destination.DestinationType;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.multiprotocol.rev171207.update.attributes.MpReachNlri;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.multiprotocol.rev171207.update.attributes.MpReachNlriBuilder;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.multiprotocol.rev171207.update.attributes.MpUnreachNlri;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.multiprotocol.rev171207.update.attributes.MpUnreachNlriBuilder;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.multiprotocol.rev171207.update.attributes.mp.reach.nlri.AdvertizedRoutes;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.multiprotocol.rev171207.update.attributes.mp.reach.nlri.AdvertizedRoutesBuilder;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.multiprotocol.rev171207.update.attributes.mp.unreach.nlri.WithdrawnRoutes;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.multiprotocol.rev171207.update.attributes.mp.unreach.nlri.WithdrawnRoutesBuilder;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.rib.rev171207.Route;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.rib.rev171207.rib.tables.Routes;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.types.rev130919.AddressFamily;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.types.rev130919.SubsequentAddressFamily;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.types.rev130919.next.hop.CNextHop;
import org.opendaylight.yangtools.yang.binding.DataObject;
import org.opendaylight.yangtools.yang.binding.util.BindingReflections;
import org.opendaylight.yangtools.yang.common.QName;
import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier.NodeIdentifier;
import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier.NodeIdentifierWithPredicates;
import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier.PathArgument;
import org.opendaylight.yangtools.yang.data.api.schema.ChoiceNode;
import org.opendaylight.yangtools.yang.data.api.schema.ContainerNode;
import org.opendaylight.yangtools.yang.data.api.schema.DataContainerChild;
import org.opendaylight.yangtools.yang.data.api.schema.DataContainerNode;
import org.opendaylight.yangtools.yang.data.api.schema.MapEntryNode;
import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeCandidateNode;
import org.opendaylight.yangtools.yang.data.impl.schema.Builders;
import org.opendaylight.yangtools.yang.data.impl.schema.ImmutableNodes;
import org.opendaylight.yangtools.yang.data.impl.schema.builder.api.DataContainerNodeAttrBuilder;
import org.opendaylight.yangtools.yang.data.impl.schema.builder.api.DataContainerNodeBuilder;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

@Beta
public abstract class AbstractRIBSupport implements RIBSupport {
    private static final Logger LOG = LoggerFactory.getLogger(AbstractRIBSupport.class);
    private static final NodeIdentifier ADVERTISED_ROUTES = new NodeIdentifier(AdvertizedRoutes.QNAME);
    private static final NodeIdentifier WITHDRAWN_ROUTES = new NodeIdentifier(WithdrawnRoutes.QNAME);
    private static final NodeIdentifier DESTINATION_TYPE = new NodeIdentifier(DestinationType.QNAME);
    private static final NodeIdentifier ROUTES = new NodeIdentifier(Routes.QNAME);
    private static final ApplyRoute DELETE_ROUTE = new DeleteRoute();

    private final NodeIdentifier routesContainerIdentifier;
    private final NodeIdentifier routesListIdentifier;
    private final NodeIdentifier routeAttributesIdentifier;
    private final Class<? extends Routes> cazeClass;
    private final Class<? extends DataObject> containerClass;
    private final Class<? extends Route> listClass;
    private final ApplyRoute putRoute = new PutRoute();
    private final ChoiceNode emptyRoutes;
    private final QName routeQname;
    private final Class<? extends AddressFamily> afiClass;
    private final Class<? extends SubsequentAddressFamily> safiClass;
    private final NodeIdentifier destinationNid;

    /**
     * Default constructor. Requires the QName of the container augmented under the routes choice
     * node in instantiations of the rib grouping. It is assumed that this container is defined by
     * the same model which populates it with route grouping instantiation, and by extension with
     * the route attributes container.
     * @param cazeClass Binding class of the AFI/SAFI-specific case statement, must not be null
     * @param containerClass Binding class of the container in routes choice, must not be null.
     * @param listClass Binding class of the route list, nust not be null;
     * @param afiClass address Family Class
     * @param safiClass SubsequentAddressFamily
     * @param destinationQname destination Qname
     */
    protected AbstractRIBSupport(final Class<? extends Routes> cazeClass, final Class<? extends DataObject> containerClass,
        final Class<? extends Route> listClass, final Class<? extends AddressFamily> afiClass, final Class<? extends SubsequentAddressFamily> safiClass,
        final QName destinationQname) {
        final QName qname = BindingReflections.findQName(containerClass).intern();
        this.routesContainerIdentifier = new NodeIdentifier(qname);
        this.routeAttributesIdentifier = new NodeIdentifier(QName.create(qname, Attributes.QNAME.getLocalName().intern()));
        this.cazeClass = requireNonNull(cazeClass);
        this.containerClass = requireNonNull(containerClass);
        this.listClass = requireNonNull(listClass);
        this.routeQname = QName.create(qname, BindingReflections.findQName(listClass).intern().getLocalName());
        this.routesListIdentifier = new NodeIdentifier(this.routeQname);
        this.emptyRoutes = Builders.choiceBuilder().withNodeIdentifier(ROUTES).addChild(Builders.containerBuilder()
            .withNodeIdentifier(routesContainerIdentifier()).withChild(ImmutableNodes.mapNodeBuilder(this.routeQname).build()).build()).build();
        this.afiClass = afiClass;
        this.safiClass = safiClass;
        this.destinationNid = new NodeIdentifier(destinationQname);
    }

    @Nonnull
    @Override
    public final Class<? extends Routes> routesCaseClass() {
        return this.cazeClass;
    }

    @Nonnull
    @Override
    public final Class<? extends DataObject> routesContainerClass() {
        return this.containerClass;
    }

    @Nonnull
    @Override
    public final Class<? extends Route> routesListClass() {
        return this.listClass;
    }

    @Nonnull
    @Override
    public final ChoiceNode emptyRoutes() {
        return this.emptyRoutes;
    }

    public final QName routeQName() {
        return this.routeQname;
    }

    protected final NodeIdentifier routeNid() {
        return this.routesListIdentifier;
    }

    @Nonnull
    @Override
    public final Class<? extends AddressFamily> getAfi() {
        return this.afiClass;
    }

    @Nonnull
    @Override
    public final Class<? extends SubsequentAddressFamily> getSafi() {
        return this.safiClass;
    }

    /**
     * Build MpReachNlri object from DOM representation.
     *
     * @param routes Collection of MapEntryNode DOM representation of routes
     * @param hop CNextHop as it was parsed from Attributes, to be included in MpReach object
     * @return MpReachNlri
     */
    private MpReachNlri buildReach(final Collection<MapEntryNode> routes, final CNextHop hop) {
        final MpReachNlriBuilder mb = new MpReachNlriBuilder();
        mb.setAfi(this.getAfi());
        mb.setSafi(this.getSafi());
        mb.setCNextHop(hop);
        mb.setAdvertizedRoutes(new AdvertizedRoutesBuilder().setDestinationType(buildDestination(routes)).build());
        return mb.build();
    }

    /**
     * Build MpUnReachNlri object from DOM representation.
     *
     * @param routes Collection of MapEntryNode DOM representation of routes
     * @return MpUnreachNlri
     */
    private MpUnreachNlri buildUnreach(final Collection<MapEntryNode> routes) {
        final MpUnreachNlriBuilder mb = new MpUnreachNlriBuilder();
        mb.setAfi(this.getAfi());
        mb.setSafi(this.getSafi());
        mb.setWithdrawnRoutes(new WithdrawnRoutesBuilder().setDestinationType(buildWithdrawnDestination(routes)).build());
        return mb.build();
    }

    @Nonnull
    protected abstract DestinationType buildDestination(@Nonnull final Collection<MapEntryNode> routes);
    @Nonnull
    protected abstract DestinationType buildWithdrawnDestination(@Nonnull final Collection<MapEntryNode> routes);

    /**
     * Return the {@link NodeIdentifier} of the AFI/SAFI-specific container under
     * the RIB routes.
     *
     * @return Container identifier, may not be null.
     */
    protected final NodeIdentifier routesContainerIdentifier() {
        return this.routesContainerIdentifier;
    }

    /**
     * Return the {@link NodeIdentifier} of the AFI/SAFI-specific container under
     * the NLRI destination.
     *
     * @return Container identifier, may not be null.
     */
    private NodeIdentifier destinationContainerIdentifier() {
        return this.destinationNid;
    }

    /**
     * Given the destination as ContainerNode, implementation needs to parse the DOM model
     * from this point onward:
     *
     * {@code /bgp-mp:mp-unreach-nlri/bgp-mp:withdrawn-routes/bgp-mp:destination-type }
     *
     * and delete the routes from its RIBs.
     *
     * @param tx DOMDataWriteTransaction to be passed into implementation
     * @param tablePath YangInstanceIdentifier to be passed into implementation
     * @param destination ContainerNode DOM representation of NLRI in Update message
     * @param routesNodeId NodeIdentifier
     */
    private void deleteDestinationRoutes(final DOMDataWriteTransaction tx, final YangInstanceIdentifier tablePath,
        final ContainerNode destination, final NodeIdentifier routesNodeId) {
        processDestination(tx, tablePath.node(routesNodeId), destination, null, DELETE_ROUTE);
    }

    /**
     * Given the destination as ContainerNode, implementation needs to parse the DOM model
     * from this point onward:
     *
     * {@code /bgp-mp:mp-reach-nlri/bgp-mp:advertized-routes/bgp-mp:destination-type }
     *
     * and put the routes to its RIBs.
     *
     * @param tx DOMDataWriteTransaction to be passed into implementation
     * @param tablePath YangInstanceIdentifier to be passed into implementation
     * @param destination ContainerNode DOM representation of NLRI in Update message
     * @param attributes ContainerNode to be passed into implementation
     * @param routesNodeId NodeIdentifier
     */
    private void putDestinationRoutes(final DOMDataWriteTransaction tx, final YangInstanceIdentifier tablePath,
        final ContainerNode destination, final ContainerNode attributes, final NodeIdentifier routesNodeId) {
        processDestination(tx, tablePath.node(routesNodeId), destination, attributes, this.putRoute);
    }

    protected abstract void processDestination(final DOMDataWriteTransaction tx, final YangInstanceIdentifier routesPath, final ContainerNode destination,
        final ContainerNode attributes, final ApplyRoute applyFunction);

    private static ContainerNode getDestination(final DataContainerChild<? extends PathArgument, ?> routes, final NodeIdentifier destinationId) {
        if (routes instanceof ContainerNode) {
            final Optional<DataContainerChild<? extends PathArgument, ?>> maybeDestination = ((ContainerNode)routes).getChild(DESTINATION_TYPE);
            if (maybeDestination.isPresent()) {
                final DataContainerChild<? extends PathArgument, ?> destination = maybeDestination.get();
                if (destination instanceof ChoiceNode) {
                    final Optional<DataContainerChild<? extends PathArgument, ?>> maybeRet = ((ChoiceNode)destination).getChild(destinationId);
                    if (maybeRet.isPresent()) {
                        final DataContainerChild<? extends PathArgument, ?> ret = maybeRet.get();
                        if (ret instanceof ContainerNode) {
                            return (ContainerNode)ret;
                        }

                        LOG.debug("Specified node {} is not a container, ignoring it", ret);
                    } else {
                        LOG.debug("Specified container {} is not present in destination {}", destinationId, destination);
                    }
                } else {
                    LOG.warn("Destination {} is not a choice, ignoring it", destination);
                }
            } else {
                LOG.debug("Destination is not present in routes {}", routes);
            }
        } else {
            LOG.warn("Advertized routes {} are not a container, ignoring it", routes);
        }

        return null;
    }

    @Override
    public final NodeIdentifier routeAttributesIdentifier() {
        return this.routeAttributesIdentifier;
    }

    @Override
    public final Collection<DataTreeCandidateNode> changedRoutes(final DataTreeCandidateNode routes) {
        final DataTreeCandidateNode myRoutes = routes.getModifiedChild(this.routesContainerIdentifier);
        if (myRoutes == null) {
            return Collections.emptySet();
        }
        final DataTreeCandidateNode routesMap = myRoutes.getModifiedChild(routeNid());
        if (routesMap == null) {
            return Collections.emptySet();
        }
        // Well, given the remote possibility of augmentation, we should perform a filter here,
        // to make sure the type matches what routeType() reports.
        return routesMap.getChildNodes();
    }

    @Override
    public final YangInstanceIdentifier routePath(final YangInstanceIdentifier routesPath, final PathArgument routeId) {
        return routesPath.node(this.routesContainerIdentifier).node(routeNid()).node(routeId);
    }

    @Override
    public final void deleteRoutes(final DOMDataWriteTransaction tx, final YangInstanceIdentifier tablePath, final ContainerNode nlri) {
        deleteRoutes(tx, tablePath, nlri, ROUTES);
    }

    @Override
    public final void putRoutes(final DOMDataWriteTransaction tx, final YangInstanceIdentifier tablePath, final ContainerNode nlri, final ContainerNode attributes) {
        putRoutes(tx, tablePath, nlri, attributes, ROUTES);
    }

    @Nonnull
    @Override
    public final Update buildUpdate(final Collection<MapEntryNode> advertised, final Collection<MapEntryNode> withdrawn, final Attributes attr) {
        final UpdateBuilder ub = new UpdateBuilder();
        final AttributesBuilder ab = new AttributesBuilder(attr);
        final CNextHop hop = ab.getCNextHop();

        LOG.debug("cnextHop before={}", hop);
        // do not preserve next hop in attributes if we are using MpReach
        ab.setCNextHop(null);

        if (!advertised.isEmpty()) {
            final MpReachNlri mb = buildReach(advertised, hop);
            ab.addAugmentation(Attributes1.class, new Attributes1Builder().setMpReachNlri(mb).build());
            LOG.debug("mpreach nexthop={}", mb);
        }
        if (!withdrawn.isEmpty()) {
            final MpUnreachNlri mb = buildUnreach(withdrawn);
            ab.addAugmentation(Attributes2.class, new Attributes2Builder().setMpUnreachNlri(mb).build());
            LOG.debug("mpunrach mb={}", mb);
        }

        ub.setAttributes(ab.build());
        LOG.debug("update {}", ub.build());
        return ub.build();
    }

    @Override
    public final void deleteRoutes(final DOMDataWriteTransaction tx, final YangInstanceIdentifier tablePath, final ContainerNode nlri,
            final NodeIdentifier routesNodeId) {
        final Optional<DataContainerChild<? extends PathArgument, ?>> maybeRoutes = nlri.getChild(WITHDRAWN_ROUTES);
        if (maybeRoutes.isPresent()) {
            final ContainerNode destination = getDestination(maybeRoutes.get(), destinationContainerIdentifier());
            if (destination != null) {
                deleteDestinationRoutes(tx, tablePath, destination, routesNodeId);
            }
        } else {
            LOG.debug("Withdrawn routes are not present in NLRI {}", nlri);
        }
    }

    @Override
    public final void putRoutes(final DOMDataWriteTransaction tx, final YangInstanceIdentifier tablePath, final ContainerNode nlri,
            final ContainerNode attributes, final NodeIdentifier routesNodeId) {
        final Optional<DataContainerChild<? extends PathArgument, ?>> maybeRoutes = nlri.getChild(ADVERTISED_ROUTES);
        if (maybeRoutes.isPresent()) {
            final ContainerNode destination = getDestination(maybeRoutes.get(), destinationContainerIdentifier());
            if (destination != null) {
                putDestinationRoutes(tx, tablePath, destination, attributes, routesNodeId);
            }
        } else {
            LOG.debug("Advertized routes are not present in NLRI {}", nlri);
        }
    }

    private static final class DeleteRoute implements ApplyRoute {
        @Override
        public final void apply(final DOMDataWriteTransaction tx, final YangInstanceIdentifier base, final NodeIdentifierWithPredicates routeKey,
            final DataContainerNode<?> route, final ContainerNode attributes) {
            tx.delete(LogicalDatastoreType.OPERATIONAL, base.node(routeKey));
        }
    }

    private final class PutRoute implements ApplyRoute {
        @Override
        public void apply(final DOMDataWriteTransaction tx, final YangInstanceIdentifier base, final NodeIdentifierWithPredicates routeKey,
            final DataContainerNode<?> route, final ContainerNode attributes) {
            // Build the DataContainer data
            final DataContainerNodeBuilder<NodeIdentifierWithPredicates, MapEntryNode> b = ImmutableNodes.mapEntryBuilder();
            b.withNodeIdentifier(routeKey);

            route.getValue().forEach(b::withChild);
            // Add attributes
            final DataContainerNodeAttrBuilder<NodeIdentifier, ContainerNode> cb = Builders.containerBuilder(attributes);
            cb.withNodeIdentifier(routeAttributesIdentifier());
            b.withChild(cb.build());
            tx.put(LogicalDatastoreType.OPERATIONAL, base.node(routeKey), b.build());
        }
    }
}