/*
 * 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 org.opendaylight.controller.cluster.databroker.actors.dds;

import com.google.common.annotations.Beta;
import com.google.common.util.concurrent.FluentFuture;
import java.util.Optional;
import org.opendaylight.controller.cluster.access.concepts.TransactionIdentifier;
import org.opendaylight.controller.cluster.datastore.utils.RootScatterGather;
import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;

/**
 * Snapshot of the datastore state. Note this snapshot is not consistent across shards because sub-shard snapshots are
 * created lazily.
 *
 * @author Robert Varga
 */
@Beta
public class ClientSnapshot extends AbstractClientHandle<AbstractProxyTransaction> {
    // Hidden to prevent outside instantiation
    ClientSnapshot(final AbstractClientHistory parent, final TransactionIdentifier transactionId) {
        super(parent, transactionId);
    }

    public FluentFuture<Boolean> exists(final YangInstanceIdentifier path) {
        return ensureProxy(path).exists(path);
    }

    public FluentFuture<Optional<NormalizedNode>> read(final YangInstanceIdentifier path) {
        return path.isEmpty() ? readRoot() : ensureProxy(path).read(path);
    }

    private FluentFuture<Optional<NormalizedNode>> readRoot() {
        return RootScatterGather.gather(parent().actorUtils(), ensureAllProxies()
            .map(proxy -> proxy.read(YangInstanceIdentifier.empty())));
    }

    @Override
    final AbstractProxyTransaction createProxy(final Long shard) {
        return parent().createSnapshotProxy(getIdentifier(), shard);
    }
}