/*
 *
 *  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.cluster.datastore;

import akka.actor.ActorRef;
import akka.actor.PoisonPill;
import com.google.common.base.Optional;
import com.google.common.util.concurrent.FutureCallback;
import com.google.common.util.concurrent.Futures;
import com.google.common.util.concurrent.ListenableFuture;
import org.opendaylight.controller.cluster.datastore.jmx.mbeans.shard.ShardStats;
import org.opendaylight.controller.cluster.datastore.messages.CreateSnapshot;
import org.opendaylight.controller.cluster.datastore.messages.DataExists;
import org.opendaylight.controller.cluster.datastore.messages.ReadData;
import org.opendaylight.controller.cluster.datastore.utils.SerializationUtils;
import org.opendaylight.controller.cluster.raft.base.messages.CaptureSnapshotReply;
import org.opendaylight.controller.sal.core.spi.data.DOMStoreReadTransaction;
import org.opendaylight.controller.sal.core.spi.data.DOMStoreTransaction;
import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;

/**
 * @author: syedbahm
 * Date: 8/6/14
 */
public class ShardReadTransaction extends ShardTransaction {
    private static final YangInstanceIdentifier DATASTORE_ROOT = YangInstanceIdentifier.builder().build();

    private final DOMStoreReadTransaction transaction;

    public ShardReadTransaction(DOMStoreReadTransaction transaction, ActorRef shardActor,
            ShardStats shardStats, String transactionID, short clientTxVersion) {
        super(shardActor, shardStats, transactionID, clientTxVersion);
        this.transaction = transaction;
    }

    @Override
    public void handleReceive(Object message) throws Exception {
        if(message instanceof ReadData) {
            readData(transaction, (ReadData) message, !SERIALIZED_REPLY);

        } else if (message instanceof DataExists) {
            dataExists(transaction, (DataExists) message, !SERIALIZED_REPLY);
        } else if (message instanceof CreateSnapshot) {
            createSnapshot();
        } else if(ReadData.SERIALIZABLE_CLASS.equals(message.getClass())) {
            readData(transaction, ReadData.fromSerializable(message), SERIALIZED_REPLY);

        } else if(DataExists.SERIALIZABLE_CLASS.equals(message.getClass())) {
            dataExists(transaction, DataExists.fromSerializable(message), SERIALIZED_REPLY);

        } else {
            super.handleReceive(message);
        }
    }

    private void createSnapshot() {

        // This is a special message sent by the shard to send back a serialized snapshot of the whole
        // data store tree. This transaction was created for that purpose only so we can
        // self-destruct after sending the reply.

        final ActorRef sender = getSender();
        final ActorRef self = getSelf();
        final ListenableFuture<Optional<NormalizedNode<?, ?>>> future = transaction.read(DATASTORE_ROOT);

        Futures.addCallback(future, new FutureCallback<Optional<NormalizedNode<?, ?>>>() {
            @Override
            public void onSuccess(Optional<NormalizedNode<?, ?>> result) {
                byte[] serialized = SerializationUtils.serializeNormalizedNode(result.get());
                sender.tell(new CaptureSnapshotReply(serialized), self);

                self.tell(PoisonPill.getInstance(), self);
            }

            @Override
            public void onFailure(Throwable t) {
                sender.tell(new akka.actor.Status.Failure(t), self);

                self.tell(PoisonPill.getInstance(), self);
            }
        });
    }

    @Override
    protected DOMStoreTransaction getDOMStoreTransaction() {
        return transaction;
    }

    @Override
    protected boolean returnCloseTransactionReply() {
        return false;
    }
}