/*
 * Copyright (c) 2014 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.controller.md.sal.dom.store.impl;

import java.util.Collection;
import java.util.Collections;
import java.util.concurrent.ExecutorService;
import javax.annotation.Nonnull;
import org.opendaylight.controller.md.sal.dom.api.DOMDataTreeChangeListener;
import org.opendaylight.controller.md.sal.dom.spi.AbstractDOMDataTreeChangeListenerRegistration;
import org.opendaylight.controller.sal.core.spi.data.AbstractDOMStoreTreeChangePublisher;
import org.opendaylight.yangtools.util.concurrent.QueuedNotificationManager;
import org.opendaylight.yangtools.util.concurrent.QueuedNotificationManager.Invoker;
import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeCandidate;
import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeCandidateNode;
import org.opendaylight.yangtools.yang.data.api.schema.tree.spi.DefaultDataTreeCandidate;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

final class InMemoryDOMStoreTreeChangePublisher extends AbstractDOMStoreTreeChangePublisher {
    private static final Invoker<AbstractDOMDataTreeChangeListenerRegistration<?>, DataTreeCandidate> MANAGER_INVOKER =
            new Invoker<AbstractDOMDataTreeChangeListenerRegistration<?>, DataTreeCandidate>() {
                @Override
                public void invokeListener(final AbstractDOMDataTreeChangeListenerRegistration<?> listener, final DataTreeCandidate notification) {
                    // FIXME: this is inefficient, as we could grab the entire queue for the listener and post it
                    final DOMDataTreeChangeListener inst = listener.getInstance();
                    if (inst != null) {
                        inst.onDataTreeChanged(Collections.singletonList(notification));
                    }
                }
            };
    private static final Logger LOG = LoggerFactory.getLogger(InMemoryDOMStoreTreeChangePublisher.class);
    private final QueuedNotificationManager<AbstractDOMDataTreeChangeListenerRegistration<?>, DataTreeCandidate> notificationManager;

    InMemoryDOMStoreTreeChangePublisher(final ExecutorService listenerExecutor, final int maxQueueSize) {
        notificationManager = new QueuedNotificationManager<>(listenerExecutor, MANAGER_INVOKER, maxQueueSize, "DataTreeChangeListenerQueueMgr");
    }

    @Override
    protected void notifyListeners(final Collection<AbstractDOMDataTreeChangeListenerRegistration<?>> registrations, final YangInstanceIdentifier path, final DataTreeCandidateNode node) {
        final DataTreeCandidate candidate = new DefaultDataTreeCandidate(path, node);

        for (AbstractDOMDataTreeChangeListenerRegistration<?> reg : registrations) {
            LOG.debug("Enqueueing candidate {} to registration {}", candidate, registrations);
            notificationManager.submitNotification(reg, candidate);
        }
    }

    @Override
    protected synchronized void registrationRemoved(final AbstractDOMDataTreeChangeListenerRegistration<?> registration) {
        LOG.debug("Closing registration {}", registration);

        // FIXME: remove the queue for this registration and make sure we clear it
    }

    synchronized void publishChange(@Nonnull final DataTreeCandidate candidate) {
        // Runs synchronized with registrationRemoved()
        processCandidateTree(candidate);
    }
}