/*
 * 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.Preconditions;
import java.util.Collection;
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.WriteTransaction;
import org.opendaylight.controller.md.sal.common.api.data.LogicalDatastoreType;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.vbridge.topology.rev160129.Topology1;
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.yangtools.concepts.ListenerRegistration;
import org.opendaylight.yangtools.yang.binding.DataObject;
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 Topology1 config;

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

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

    static BridgeDomain create(final DataBroker dataBroker,
            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, 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<Topology1> newConfig = mod.getModifiedAugmentation(Topology1.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 Topology1 config = data.getAugmentation(Topology1.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> child) {
        switch (child.getModificationType()) {
            case DELETE:
                LOG.debug("Topology {} node {} deleted", topology, child.getIdentifier());
                // FIXME: do something
                break;
            case SUBTREE_MODIFIED:
                LOG.debug("Topology {} node {} modified", topology, child.getIdentifier());
                // FIXME: do something
                break;
            case WRITE:
                LOG.debug("Topology {} node {} created", topology, child.getIdentifier());
                // FIXME: do something
                break;
            default:
                LOG.warn("Unhandled node modification {} in topology {}", child, topology);
                break;
        }
    }

    private void setConfiguration(final Topology1 config) {
        LOG.debug("Topology {} configuration set to {}", topology, config);

        this.config = config;
    }

    @GuardedBy("this")
    private void updateConfiguration(final DataObjectModification<Topology1> mod) {
        LOG.debug("Topology {} configuration changed", topology);

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