/*
 * Copyright (c) 2016 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 io.fd.honeycomb.vbd.impl;

import com.google.common.base.Optional;
import com.google.common.base.Preconditions;
import com.google.common.collect.ArrayListMultimap;
import com.google.common.collect.Multimap;
import com.google.common.util.concurrent.CheckedFuture;
import com.google.common.util.concurrent.FutureCallback;
import com.google.common.util.concurrent.Futures;
import java.util.Collection;
import java.util.Map;
import javax.annotation.concurrent.GuardedBy;
import org.opendaylight.controller.md.sal.binding.api.BindingTransactionChain;
import org.opendaylight.controller.md.sal.binding.api.DataBroker;
import org.opendaylight.controller.md.sal.binding.api.DataObjectModification;
import org.opendaylight.controller.md.sal.binding.api.DataObjectModification.ModificationType;
import org.opendaylight.controller.md.sal.binding.api.DataTreeChangeListener;
import org.opendaylight.controller.md.sal.binding.api.DataTreeIdentifier;
import org.opendaylight.controller.md.sal.binding.api.DataTreeModification;
import org.opendaylight.controller.md.sal.binding.api.MountPoint;
import org.opendaylight.controller.md.sal.binding.api.MountPointService;
import org.opendaylight.controller.md.sal.binding.api.ReadOnlyTransaction;
import org.opendaylight.controller.md.sal.binding.api.WriteTransaction;
import org.opendaylight.controller.md.sal.common.api.data.LogicalDatastoreType;
import org.opendaylight.controller.md.sal.common.api.data.ReadFailedException;
import org.opendaylight.controller.md.sal.common.api.data.TransactionCommitFailedException;
import org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.interfaces.rev140508.Interfaces;
import org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.interfaces.rev140508.InterfacesState;
import org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.interfaces.rev140508.interfaces.Interface;
import org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.interfaces.rev140508.interfaces.InterfaceKey;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.external.reference.rev160129.ExternalReference;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.v3po.rev150105.Vpp;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.v3po.rev150105.VppInterfaceAugmentation;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.v3po.rev150105.interfaces._interface.L2;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.v3po.rev150105.interfaces._interface.L2Builder;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.v3po.rev150105.interfaces._interface.l2.interconnection.BridgeBasedBuilder;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.v3po.rev150105.vpp.BridgeDomains;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.v3po.rev150105.vpp.bridge.domains.BridgeDomainBuilder;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.v3po.rev150105.vpp.bridge.domains.BridgeDomainKey;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.vbridge.topology.rev160129.NodeVbridgeAugment;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.vbridge.topology.rev160129.TerminationPointVbridgeAugment;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.vbridge.topology.rev160129.TopologyVbridgeAugment;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.vbridge.topology.rev160129.network.topology.topology.node.BridgeMember;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.vbridge.topology.rev160129.network.topology.topology.node.BridgeMemberBuilder;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.vbridge.topology.rev160129.network.topology.topology.node.termination.point.InterfaceType;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.vbridge.topology.rev160129.network.topology.topology.node.termination.point._interface.type.UserInterface;
import org.opendaylight.yang.gen.v1.urn.tbd.params.xml.ns.yang.network.topology.rev131021.NetworkTopology;
import org.opendaylight.yang.gen.v1.urn.tbd.params.xml.ns.yang.network.topology.rev131021.NodeId;
import org.opendaylight.yang.gen.v1.urn.tbd.params.xml.ns.yang.network.topology.rev131021.TopologyId;
import org.opendaylight.yang.gen.v1.urn.tbd.params.xml.ns.yang.network.topology.rev131021.network.topology.Topology;
import org.opendaylight.yang.gen.v1.urn.tbd.params.xml.ns.yang.network.topology.rev131021.network.topology.TopologyKey;
import org.opendaylight.yang.gen.v1.urn.tbd.params.xml.ns.yang.network.topology.rev131021.network.topology.topology.Node;
import org.opendaylight.yang.gen.v1.urn.tbd.params.xml.ns.yang.network.topology.rev131021.network.topology.topology.NodeKey;
import org.opendaylight.yang.gen.v1.urn.tbd.params.xml.ns.yang.network.topology.rev131021.network.topology.topology.node.TerminationPoint;
import org.opendaylight.yang.gen.v1.urn.tbd.params.xml.ns.yang.network.topology.rev131021.node.attributes.SupportingNode;
import org.opendaylight.yangtools.concepts.ListenerRegistration;
import org.opendaylight.yangtools.yang.binding.DataObject;
import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
import org.opendaylight.yangtools.yang.binding.KeyedInstanceIdentifier;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Implementation of a single Virtual Bridge Domain. It is bound to a particular network topology instance, manages
 * bridge members and projects state into the operational data store.
 */
final class BridgeDomain implements DataTreeChangeListener<Topology> {
    private static final Logger LOG = LoggerFactory.getLogger(BridgeDomain.class);
    private final KeyedInstanceIdentifier<Topology, TopologyKey> topology;
    @GuardedBy("this")

    private final BindingTransactionChain chain;
    private final ListenerRegistration<?> reg;
    private final MountPointService mountService;
    private TopologyVbridgeAugment config;
    private final String bridgeDomainName;
    private final InstanceIdentifier<org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.v3po.rev150105.vpp.bridge.domains.BridgeDomain> iiBridgeDomainOnVPP;
    private final String iiBridgeDomainOnVPPRest;
    private final DataBroker dataBroker;
    private Multimap<NodeId, KeyedInstanceIdentifier<Node, NodeKey>> nodesToVpps = ArrayListMultimap.create();

    private BridgeDomain(final DataBroker dataBroker, final MountPointService mountService, final KeyedInstanceIdentifier<Topology, TopologyKey> topology,
            final BindingTransactionChain chain) {
        this.topology = Preconditions.checkNotNull(topology);
        this.chain = Preconditions.checkNotNull(chain);
        this.mountService = mountService;

        this.bridgeDomainName = topology.getKey().getTopologyId().getValue();
        this.iiBridgeDomainOnVPPRest = provideIIBrdigeDomainOnVPPRest();
        this.iiBridgeDomainOnVPP = InstanceIdentifier.create(Vpp.class)
                .child(BridgeDomains.class)
                .child(org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.v3po.rev150105.vpp.bridge.domains.BridgeDomain.class, new BridgeDomainKey(bridgeDomainName));

        this.dataBroker = dataBroker;
        reg = dataBroker.registerDataTreeChangeListener(
                                     new DataTreeIdentifier<>(LogicalDatastoreType.CONFIGURATION, topology), this);
    }

    private String provideIIBrdigeDomainOnVPPRest() {
        final StringBuilder strBuilder = new StringBuilder();
        strBuilder.append("v3po:vpp/bridge-domains/bridge-domain/");
        strBuilder.append(bridgeDomainName);
        return strBuilder.toString();
    }

    static BridgeDomain create(final DataBroker dataBroker,
                               MountPointService mountService, final KeyedInstanceIdentifier<Topology, TopologyKey> topology, final BindingTransactionChain chain) {

        LOG.debug("Wiping operational state of {}", topology);

        final WriteTransaction tx = chain.newWriteOnlyTransaction();
        tx.delete(LogicalDatastoreType.OPERATIONAL, topology);
        tx.submit();

        return new BridgeDomain(dataBroker, mountService, topology, chain);
    }

    synchronized void forceStop() {
        LOG.info("Bridge domain {} for {} going down", this, topology);
        reg.close();
        chain.close();
        LOG.info("Bridge domain {} for {} is down", this, topology);
    }

    synchronized void stop() {
        LOG.debug("Bridge domain {} for {} shutting down", this, topology);

        final WriteTransaction tx = chain.newWriteOnlyTransaction();
        tx.delete(LogicalDatastoreType.OPERATIONAL, topology);
        tx.submit();
        chain.close();
    }

    @Override
    public synchronized void onDataTreeChanged(final Collection<DataTreeModification<Topology>> changes) {
        for (DataTreeModification<Topology> c : changes) {
            LOG.debug("Domain {} for {} processing change {}", this, topology, c);

            final DataObjectModification<Topology> mod = c.getRootNode();
            switch (mod.getModificationType()) {
                case DELETE:
                    LOG.debug("Topology {} deleted, expecting shutdown", topology);
                    break;
                case SUBTREE_MODIFIED:
                    // First check if the configuration has changed
                    final DataObjectModification<TopologyVbridgeAugment> newConfig = mod.getModifiedAugmentation(TopologyVbridgeAugment.class);
                    if (newConfig != null) {
                        if (newConfig.getModificationType() != ModificationType.DELETE) {
                            LOG.debug("Topology {} modified configuration {}", topology, newConfig);
                            updateConfiguration(newConfig);
                        } else {
                            // FIXME: okay, what can we do about this one?
                            LOG.error("Topology {} configuration deleted, good luck!", topology);
                        }
                    }

                    for (DataObjectModification<? extends DataObject> child : mod.getModifiedChildren()) {
                        LOG.debug("Topology {} modified child {}", topology, child);

                        if (Node.class.isAssignableFrom(child.getDataType())) {
                            modifyNode((DataObjectModification<Node>) child);
                        }
                    }

                    break;
                case WRITE:
                    final Topology data = mod.getDataAfter();

                    // Read configuration
                    final TopologyVbridgeAugment config = data.getAugmentation(TopologyVbridgeAugment.class);
                    if (config != null) {
                        setConfiguration(config);
                    } else {
                        LOG.error("Topology {} has no configuration, good luck!", topology);
                    }

                    // FIXME: deal with nodes

                    break;
                default:
                    LOG.warn("Unhandled topology modification {}", mod);
                    break;
            }
        }
    }

    private void modifyNode(final DataObjectModification<Node> nodeMod) {
        switch (nodeMod.getModificationType()) {
            case DELETE:
                LOG.debug("Topology {} node {} deleted", topology, nodeMod.getIdentifier());
                // FIXME: do something
                break;
            case SUBTREE_MODIFIED:
                LOG.debug("Topology {} node {} modified", topology, nodeMod.getIdentifier());
                for (DataObjectModification<? extends DataObject>  nodeChild : nodeMod.getModifiedChildren()) {
                    if (TerminationPoint.class.isAssignableFrom(nodeChild.getDataType())) {
                        modifyTerminationPoint((DataObjectModification<TerminationPoint>) nodeChild,nodeMod.getDataAfter().getNodeId());
                    }
                }
                break;
            case WRITE:
                LOG.debug("Topology {} node {} created", topology, nodeMod.getIdentifier());
                final int numberVppsBeforeAddition = nodesToVpps.keySet().size();
                final Node newNode = nodeMod.getDataAfter();
                createNode(newNode);
                final int numberVppsAfterAddition = nodesToVpps.keySet().size();
                if ((numberVppsBeforeAddition < numberVppsAfterAddition) && (numberVppsBeforeAddition >= 1)) {
                    addTunnel(newNode.getNodeId());
                }
                break;
            default:
                LOG.warn("Unhandled node modification {} in topology {}", nodeMod, topology);
                break;
        }
    }

    private void addTunnel(final NodeId newNode) {
        for (Map.Entry<NodeId, KeyedInstanceIdentifier<Node, NodeKey>> entryToVpp : nodesToVpps.entries()) {
            if (!entryToVpp.getKey().equals(newNode)) {
                createTunnelEndPoint(entryToVpp.getValue());
                createTunnelEndPoint(nodesToVpps.get(newNode));
            }


        }
    }

    private void createTunnelEndPoint(Collection<KeyedInstanceIdentifier<Node, NodeKey>> keyedInstanceIdentifiers) {
        for (KeyedInstanceIdentifier<Node, NodeKey> iiToVpp : keyedInstanceIdentifiers) {
            createTunnelEndPoint(iiToVpp);
        }
    }

    private void createTunnelEndPoint(final KeyedInstanceIdentifier<Node, NodeKey> iiToVpp) {
        final DataBroker vppDataBroker = resolveDataBrokerForMountPoint(iiToVpp);
        final ReadOnlyTransaction rTx = vppDataBroker.newReadOnlyTransaction();

        final CheckedFuture<Optional<InterfacesState>, ReadFailedException> interfaceStateFuture
                = rTx.read(LogicalDatastoreType.OPERATIONAL, InstanceIdentifier.create(InterfacesState.class));
        Futures.addCallback(interfaceStateFuture, new FutureCallback<Optional<InterfacesState>>() {
            @Override
            public void onSuccess(Optional<InterfacesState> optInterfacesState) {
                if (optInterfacesState.isPresent()) {
                    for (org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.interfaces.rev140508.interfaces.state.Interface intf : optInterfacesState.get().getInterface()) {
                        //TODO find interface with IP address set
                    }
                }

            }

            @Override
            public void onFailure(Throwable t) {

            }
        });


    }


    private void modifyTerminationPoint(final DataObjectModification<TerminationPoint> nodeChild, final NodeId nodeId) {
        final TerminationPoint terminationPoint = nodeChild.getDataAfter();
        final TerminationPointVbridgeAugment termPointVbridgeAug = terminationPoint.getAugmentation(TerminationPointVbridgeAugment.class);
        if (termPointVbridgeAug != null) {
            final Collection<KeyedInstanceIdentifier<Node, NodeKey>> instanceIdentifiersVPP = nodesToVpps.get(nodeId);
            //TODO: probably iterate via all instance identifiers.
            if (!instanceIdentifiersVPP.isEmpty()) {
                final DataBroker dataBroker = resolveDataBrokerForMountPoint(instanceIdentifiersVPP.iterator().next());
                addInterfaceToBridgeDomainOnVpp(dataBroker, termPointVbridgeAug);
            }
        }
    }

    private void addInterfaceToBridgeDomainOnVpp(final DataBroker vppDataBroker, final TerminationPointVbridgeAugment termPointVbridgeAug) {
        final InterfaceType interfaceType = termPointVbridgeAug.getInterfaceType();
        if (interfaceType instanceof UserInterface) {
            //REMARK: according contract in YANG model this should be URI to data on mount point (accroding to RESTCONF)
            //It was much more easier to just await concrete interface name, thus isn't necessary parse it (splitting on '/')
            final ExternalReference userInterface = ((UserInterface) interfaceType).getUserInterface();
            final KeyedInstanceIdentifier<Interface, InterfaceKey> iiToVpp =
                    InstanceIdentifier.create(Interfaces.class)
                            .child(Interface.class, new InterfaceKey(userInterface.getValue()));
            InstanceIdentifier<L2> iiToV3poL2 = iiToVpp.augmentation(VppInterfaceAugmentation.class).child(L2.class);
            LOG.debug("Writing L2 data to configuration DS to concrete interface.");
            final WriteTransaction wTx = vppDataBroker.newWriteOnlyTransaction();
            wTx.put(LogicalDatastoreType.CONFIGURATION, iiToV3poL2, prepareL2Data());
            wTx.submit();
        }
    }

    private L2 prepareL2Data() {
        final L2Builder l2Builder = new L2Builder();
        final BridgeBasedBuilder bridgeBasedBuilder = new BridgeBasedBuilder();
        bridgeBasedBuilder.setSplitHorizonGroup((short) 0);
        bridgeBasedBuilder.setBridgedVirtualInterface(false);
        bridgeBasedBuilder.setBridgeDomain(bridgeDomainName);
        l2Builder.setInterconnection(bridgeBasedBuilder.build());
        return l2Builder.build();
    }


    private DataBroker resolveDataBrokerForMountPoint(final InstanceIdentifier<?> iiToMountPoint) {
        final Optional<MountPoint> vppMountPointOpt = mountService.getMountPoint(iiToMountPoint);
        if (vppMountPointOpt.isPresent()) {
            final MountPoint vppMountPoint = vppMountPointOpt.get();
            final Optional<DataBroker> dataBrokerOpt = vppMountPoint.getService(DataBroker.class);
            if (dataBrokerOpt.isPresent()) {
                return dataBrokerOpt.get();
            }
        }
        return null;
    }

    private void createNode(final Node node) {
        for (SupportingNode supportingNode : node.getSupportingNode()) {
            final NodeId nodeMount = supportingNode.getNodeRef();
            final TopologyId topologyMount = supportingNode.getTopologyRef();

            final KeyedInstanceIdentifier<Node, NodeKey> iiToMount = InstanceIdentifier
                    .create(NetworkTopology.class)
                    .child(Topology.class, new TopologyKey(topologyMount))
                    .child(Node.class, new NodeKey(nodeMount));
            nodesToVpps.put(node.getNodeId(), iiToMount);
            final DataBroker dataBrokerOfMount = resolveDataBrokerForMountPoint(iiToMount);
            addVppToBridgeDomain(dataBrokerOfMount, node);
        }
    }

    private void addVppToBridgeDomain(final DataBroker vppDataBroker, final Node node) {
        if (vppDataBroker != null) {
            final WriteTransaction wTx = vppDataBroker.newWriteOnlyTransaction();
            wTx.put(LogicalDatastoreType.CONFIGURATION, iiBridgeDomainOnVPP, prepareNewBridgeDomainData());
            final CheckedFuture<Void, TransactionCommitFailedException> addVppToBridgeDomainFuture = wTx.submit();
            addSupportingBridgeDomain(addVppToBridgeDomainFuture, node);
        }
    }

    private void addSupportingBridgeDomain(final CheckedFuture<Void, TransactionCommitFailedException> addVppToBridgeDomainFuture, final Node node) {
        Futures.addCallback(addVppToBridgeDomainFuture, new FutureCallback() {
            @Override
            public void onSuccess(Object result) {
                LOG.debug("Storing bridge member to operational DS....");
                final BridgeMemberBuilder bridgeMemberBuilder = new BridgeMemberBuilder();
                bridgeMemberBuilder.setSupportingBridgeDomain(new ExternalReference(iiBridgeDomainOnVPPRest));
                final InstanceIdentifier<BridgeMember> iiToBridgeMember = topology.child(Node.class, node.getKey()).augmentation(NodeVbridgeAugment.class).child(BridgeMember.class);
                final WriteTransaction wTx = chain.newWriteOnlyTransaction();
                wTx.put(LogicalDatastoreType.OPERATIONAL, iiToBridgeMember, bridgeMemberBuilder.build(), true);
                wTx.submit();
            }

            @Override
            public void onFailure(Throwable t) {
                //TODO handle this state
            }
        });

    }

    private org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.v3po.rev150105.vpp.bridge.domains.BridgeDomain
        prepareNewBridgeDomainData() {
            final BridgeDomainBuilder bridgeDomainBuilder = new BridgeDomainBuilder(config);
            bridgeDomainBuilder.setName(topology.getKey().getTopologyId().getValue());
            return bridgeDomainBuilder.build();
    }

    private void setConfiguration(final TopologyVbridgeAugment config) {
        LOG.debug("Topology {} configuration set to {}", topology, config);

        this.config = config;
    }

    @GuardedBy("this")
    private void updateConfiguration(final DataObjectModification<TopologyVbridgeAugment> mod) {
        LOG.debug("Topology {} configuration changed", topology);

        // FIXME: do something smarter
        setConfiguration(mod.getDataAfter());
    }
}