/*
 * Copyright (c) 2016 Ericsson India Global Services Pvt Ltd. 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.genius.interfacemanager.listeners;

import java.util.Collection;
import org.opendaylight.controller.md.sal.binding.api.ClusteredDataTreeChangeListener;
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.DataTreeIdentifier;
import org.opendaylight.controller.md.sal.binding.api.DataTreeModification;
import org.opendaylight.controller.md.sal.common.api.data.LogicalDatastoreType;
import org.opendaylight.genius.interfacemanager.commons.InterfaceMetaUtils;
import org.opendaylight.yang.gen.v1.urn.opendaylight.genius.interfacemanager.meta.rev160406.BridgeRefInfo;
import org.opendaylight.yang.gen.v1.urn.opendaylight.genius.interfacemanager.meta.rev160406.bridge.ref.info.BridgeRefEntry;
import org.opendaylight.yangtools.concepts.ListenerRegistration;
import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * This class listens for bridgeRefEntry creation/removal/update in Operational DS
 * and update the bridgeRefEntryCache as per changes in DS.
 *
 */
public class CacheBridgeRefEntryListener implements ClusteredDataTreeChangeListener<BridgeRefEntry>{

    private static final Logger LOG = LoggerFactory.getLogger(CacheBridgeRefEntryListener.class);
    private final DataBroker db;
    private ListenerRegistration<CacheBridgeRefEntryListener> registration;

    public CacheBridgeRefEntryListener(DataBroker broker) {
        this.db = broker;
        registerListener(db);
    }

    private void registerListener(DataBroker dataBroker) {
        final DataTreeIdentifier<BridgeRefEntry> treeId =
                new DataTreeIdentifier<>(LogicalDatastoreType.OPERATIONAL, getWildcardPath());
        try {
            LOG.trace("Registering on path: {}", treeId);
            registration = dataBroker.registerDataTreeChangeListener(treeId, CacheBridgeRefEntryListener.this);
        } catch (final Exception e) {
            LOG.warn("CacheBridgeRefEntryConfigListener registration failed", e);
        }
    }

    protected InstanceIdentifier<BridgeRefEntry> getWildcardPath() {
        return InstanceIdentifier.create(BridgeRefInfo.class).child(BridgeRefEntry.class);
    }

    public void close() throws Exception {
        if(registration != null) {
            registration.close();
        }
    }

    @Override
    public void onDataTreeChanged(Collection<DataTreeModification<BridgeRefEntry>> changes) {
        for (DataTreeModification<BridgeRefEntry> change : changes) {
        final DataObjectModification<BridgeRefEntry> mod = change.getRootNode();
            switch (mod.getModificationType()) {
            case DELETE:
                /* Note: Do we want to retain entry in cache? Ref Entry missing means
                 * OVS being disconnected for now. It will either come back, or will
                 * require config to be deleted.
                 *
                 * Removing for now, can consider this as future optimization.
                 *
                 */
                InterfaceMetaUtils.removeFromBridgeRefEntryCache(mod.getDataBefore());
                break;
            case SUBTREE_MODIFIED:
            case WRITE:
                InterfaceMetaUtils.addBridgeRefEntryToCache(mod.getDataAfter());
                break;
            default:
                throw new IllegalArgumentException("Unhandled modification type " + mod.getModificationType());
            }
        }
    }


}