/*
 * Copyright (c) 2016 Brocade Communications 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.controller.cluster.datastore;

import com.google.common.base.Optional;
import java.util.function.Consumer;
import javax.annotation.concurrent.NotThreadSafe;
import org.opendaylight.controller.md.sal.common.api.data.AsyncDataBroker.DataChangeScope;
import org.opendaylight.controller.md.sal.common.api.data.AsyncDataChangeListener;
import org.opendaylight.controller.md.sal.dom.store.impl.DOMImmutableDataChangeEvent;
import org.opendaylight.controller.md.sal.dom.store.impl.DataChangeListenerRegistration;
import org.opendaylight.controller.md.sal.dom.store.impl.ResolveDataChangeEventsTask;
import org.opendaylight.controller.md.sal.dom.store.impl.tree.ListenerTree;
import org.opendaylight.yangtools.concepts.ListenerRegistration;
import org.opendaylight.yangtools.util.concurrent.NotificationManager;
import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeCandidate;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Default implementation of ShardDataChangeListenerPublisher that directly generates and publishes
 * notifications for DataChangeListeners.
 *
 * @author Thomas Pantelis
 */
@NotThreadSafe
final class DefaultShardDataChangeListenerPublisher implements ShardDataChangeListenerPublisher,
        NotificationManager<DataChangeListenerRegistration<?>, DOMImmutableDataChangeEvent> {
    private static final Logger LOG = LoggerFactory.getLogger(DefaultShardDataChangeListenerPublisher.class);

    private final ListenerTree dataChangeListenerTree = ListenerTree.create();
    private final String logContext;

    DefaultShardDataChangeListenerPublisher(String logContext) {
        this.logContext = logContext;
    }

    @Override
    public void submitNotification(final DataChangeListenerRegistration<?> listener,
            final DOMImmutableDataChangeEvent notification) {
        LOG.debug("{}: Notifying listener {} about {}", logContext, listener.getInstance(), notification);

        listener.getInstance().onDataChanged(notification);
    }

    @Override
    public void submitNotifications(final DataChangeListenerRegistration<?> listener,
            final Iterable<DOMImmutableDataChangeEvent> notifications) {
        final AsyncDataChangeListener<YangInstanceIdentifier, NormalizedNode<?, ?>> instance = listener.getInstance();
        LOG.debug("{}: Notifying listener {} about {}", logContext, instance, notifications);

        for (DOMImmutableDataChangeEvent n : notifications) {
            instance.onDataChanged(n);
        }
    }

    @Override
    public void publishChanges(DataTreeCandidate candidate) {
        ResolveDataChangeEventsTask.create(candidate, dataChangeListenerTree).resolve(this);
    }

    @Override
    public void registerDataChangeListener(YangInstanceIdentifier path,
            AsyncDataChangeListener<YangInstanceIdentifier, NormalizedNode<?, ?>> listener, DataChangeScope scope,
            Optional<DataTreeCandidate> initialState,
            Consumer<ListenerRegistration<AsyncDataChangeListener<YangInstanceIdentifier, NormalizedNode<?, ?>>>>
                    onRegistration) {
        final DataChangeListenerRegistration<AsyncDataChangeListener<YangInstanceIdentifier, NormalizedNode<?, ?>>>
                registration = dataChangeListenerTree.registerDataChangeListener(path, listener, scope);

        onRegistration.accept(registration);

        if (initialState.isPresent()) {
            notifySingleListener(path, listener, scope, initialState.get(), logContext);
        }
    }

    static void notifySingleListener(final YangInstanceIdentifier path,
            final AsyncDataChangeListener<YangInstanceIdentifier,NormalizedNode<?, ?>> listener,
            final DataChangeScope scope, final DataTreeCandidate initialState, String logContext) {
        DefaultShardDataChangeListenerPublisher publisher = new DefaultShardDataChangeListenerPublisher(logContext);
        publisher.registerDataChangeListener(path, listener, scope, Optional.absent(), noop -> { });
        publisher.publishChanges(initialState);
    }
}