/*
 * 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 akka.actor.Props;
import akka.actor.ReceiveTimeout;
import akka.japi.Creator;
import akka.serialization.Serialization;
import com.google.common.base.Optional;
import com.google.common.util.concurrent.CheckedFuture;
import org.opendaylight.controller.cluster.common.actor.AbstractUntypedActor;
import org.opendaylight.controller.cluster.datastore.exceptions.UnknownMessageException;
import org.opendaylight.controller.cluster.datastore.jmx.mbeans.shard.ShardStats;
import org.opendaylight.controller.cluster.datastore.messages.CloseTransaction;
import org.opendaylight.controller.cluster.datastore.messages.CloseTransactionReply;
import org.opendaylight.controller.cluster.datastore.messages.DataExists;
import org.opendaylight.controller.cluster.datastore.messages.DataExistsReply;
import org.opendaylight.controller.cluster.datastore.messages.DeleteData;
import org.opendaylight.controller.cluster.datastore.messages.DeleteDataReply;
import org.opendaylight.controller.cluster.datastore.messages.MergeData;
import org.opendaylight.controller.cluster.datastore.messages.MergeDataReply;
import org.opendaylight.controller.cluster.datastore.messages.ReadData;
import org.opendaylight.controller.cluster.datastore.messages.ReadDataReply;
import org.opendaylight.controller.cluster.datastore.messages.ReadyTransaction;
import org.opendaylight.controller.cluster.datastore.messages.ReadyTransactionReply;
import org.opendaylight.controller.cluster.datastore.messages.WriteData;
import org.opendaylight.controller.cluster.datastore.messages.WriteDataReply;
import org.opendaylight.controller.cluster.datastore.modification.CompositeModification;
import org.opendaylight.controller.cluster.datastore.modification.DeleteModification;
import org.opendaylight.controller.cluster.datastore.modification.ImmutableCompositeModification;
import org.opendaylight.controller.cluster.datastore.modification.MergeModification;
import org.opendaylight.controller.cluster.datastore.modification.MutableCompositeModification;
import org.opendaylight.controller.cluster.datastore.modification.WriteModification;
import org.opendaylight.controller.md.sal.common.api.data.ReadFailedException;
import org.opendaylight.controller.sal.core.spi.data.DOMStoreReadTransaction;
import org.opendaylight.controller.sal.core.spi.data.DOMStoreReadWriteTransaction;
import org.opendaylight.controller.sal.core.spi.data.DOMStoreThreePhaseCommitCohort;
import org.opendaylight.controller.sal.core.spi.data.DOMStoreTransaction;
import org.opendaylight.controller.sal.core.spi.data.DOMStoreWriteTransaction;
import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
import org.opendaylight.yangtools.yang.model.api.SchemaContext;

/**
 * The ShardTransaction Actor represents a remote transaction
 * <p>
 * The ShardTransaction Actor delegates all actions to DOMDataReadWriteTransaction
 * </p>
 * <p>
 * Even though the DOMStore and the DOMStoreTransactionChain implement multiple types of transactions
 * the ShardTransaction Actor only works with read-write transactions. This is just to keep the logic simple. At this
 * time there are no known advantages for creating a read-only or write-only transaction which may change over time
 * at which point we can optimize things in the distributed store as well.
 * </p>
 * <p>
 * Handles Messages <br/>
 * ---------------- <br/>
 * <li> {@link org.opendaylight.controller.cluster.datastore.messages.ReadData}
 * <li> {@link org.opendaylight.controller.cluster.datastore.messages.WriteData}
 * <li> {@link org.opendaylight.controller.cluster.datastore.messages.MergeData}
 * <li> {@link org.opendaylight.controller.cluster.datastore.messages.DeleteData}
 * <li> {@link org.opendaylight.controller.cluster.datastore.messages.ReadyTransaction}
 * <li> {@link org.opendaylight.controller.cluster.datastore.messages.CloseTransaction}
 * </p>
 */
public abstract class ShardTransaction extends AbstractUntypedActor {

    private final ActorRef shardActor;
    protected final SchemaContext schemaContext;
    private final ShardStats shardStats;

    private final MutableCompositeModification modification = new MutableCompositeModification();

    protected ShardTransaction(ActorRef shardActor, SchemaContext schemaContext,
            ShardStats shardStats) {
        this.shardActor = shardActor;
        this.schemaContext = schemaContext;
        this.shardStats = shardStats;
    }

    public static Props props(DOMStoreTransaction transaction, ActorRef shardActor,
            SchemaContext schemaContext,DatastoreContext datastoreContext, ShardStats shardStats) {
        return Props.create(new ShardTransactionCreator(transaction, shardActor, schemaContext,
           datastoreContext, shardStats));
    }

    protected abstract DOMStoreTransaction getDOMStoreTransaction();

    @Override
    public void handleReceive(Object message) throws Exception {
        if (message.getClass().equals(CloseTransaction.SERIALIZABLE_CLASS)) {
            closeTransaction(true);
        } else if (message instanceof GetCompositedModification) {
            // This is here for testing only
            getSender().tell(new GetCompositeModificationReply(
                    new ImmutableCompositeModification(modification)), getSelf());
        } else if (message instanceof ReceiveTimeout) {
            if(LOG.isDebugEnabled()) {
                LOG.debug("Got ReceiveTimeout for inactivity - closing Tx");
            }
            closeTransaction(false);
        } else {
            throw new UnknownMessageException(message);
        }
    }

    private void closeTransaction(boolean sendReply) {
        getDOMStoreTransaction().close();

        if(sendReply) {
            getSender().tell(new CloseTransactionReply().toSerializable(), getSelf());
        }

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

    protected void readData(DOMStoreReadTransaction transaction,ReadData message) {
        final ActorRef sender = getSender();
        final ActorRef self = getSelf();
        final YangInstanceIdentifier path = message.getPath();
        final CheckedFuture<Optional<NormalizedNode<?, ?>>, ReadFailedException> future =
                transaction.read(path);

        future.addListener(new Runnable() {
            @Override
            public void run() {
                try {
                    Optional<NormalizedNode<?, ?>> optional = future.checkedGet();
                    if (optional.isPresent()) {
                        sender.tell(new ReadDataReply(schemaContext,optional.get()).toSerializable(), self);
                    } else {
                        sender.tell(new ReadDataReply(schemaContext,null).toSerializable(), self);
                    }
                } catch (Exception e) {
                    shardStats.incrementFailedReadTransactionsCount();
                    sender.tell(new akka.actor.Status.Failure(e), self);
                }

            }
        }, getContext().dispatcher());
    }

    protected void dataExists(DOMStoreReadTransaction transaction, DataExists message) {
        final YangInstanceIdentifier path = message.getPath();

        try {
            Boolean exists = transaction.exists(path).checkedGet();
            getSender().tell(new DataExistsReply(exists).toSerializable(), getSelf());
        } catch (ReadFailedException e) {
            getSender().tell(new akka.actor.Status.Failure(e),getSelf());
        }

    }

    protected void writeData(DOMStoreWriteTransaction transaction, WriteData message) {
        modification.addModification(
                new WriteModification(message.getPath(), message.getData(),schemaContext));
        if(LOG.isDebugEnabled()) {
            LOG.debug("writeData at path : " + message.getPath().toString());
        }
        try {
            transaction.write(message.getPath(), message.getData());
            getSender().tell(new WriteDataReply().toSerializable(), getSelf());
        }catch(Exception e){
            getSender().tell(new akka.actor.Status.Failure(e), getSelf());
        }
    }

    protected void mergeData(DOMStoreWriteTransaction transaction, MergeData message) {
        modification.addModification(
                new MergeModification(message.getPath(), message.getData(), schemaContext));
        if(LOG.isDebugEnabled()) {
            LOG.debug("mergeData at path : " + message.getPath().toString());
        }
        try {
            transaction.merge(message.getPath(), message.getData());
            getSender().tell(new MergeDataReply().toSerializable(), getSelf());
        }catch(Exception e){
            getSender().tell(new akka.actor.Status.Failure(e), getSelf());
        }
    }

    protected void deleteData(DOMStoreWriteTransaction transaction, DeleteData message) {
        if(LOG.isDebugEnabled()) {
            LOG.debug("deleteData at path : " + message.getPath().toString());
        }
        modification.addModification(new DeleteModification(message.getPath()));
        try {
            transaction.delete(message.getPath());
            getSender().tell(new DeleteDataReply().toSerializable(), getSelf());
        }catch(Exception e){
            getSender().tell(new akka.actor.Status.Failure(e), getSelf());
        }
    }

    protected void readyTransaction(DOMStoreWriteTransaction transaction, ReadyTransaction message) {
        DOMStoreThreePhaseCommitCohort cohort =  transaction.ready();
        ActorRef cohortActor = getContext().actorOf(
            ThreePhaseCommitCohort.props(cohort, shardActor, modification, shardStats), "cohort");
        getSender().tell(new ReadyTransactionReply(
            Serialization.serializedActorPath(cohortActor)).toSerializable(), getSelf());

    }

    private static class ShardTransactionCreator implements Creator<ShardTransaction> {

        private static final long serialVersionUID = 1L;

        final DOMStoreTransaction transaction;
        final ActorRef shardActor;
        final SchemaContext schemaContext;
        final DatastoreContext datastoreContext;
        final ShardStats shardStats;

        ShardTransactionCreator(DOMStoreTransaction transaction, ActorRef shardActor,
                SchemaContext schemaContext, DatastoreContext datastoreContext,
                ShardStats shardStats) {
            this.transaction = transaction;
            this.shardActor = shardActor;
            this.shardStats = shardStats;
            this.schemaContext = schemaContext;
            this.datastoreContext = datastoreContext;
        }

        @Override
        public ShardTransaction create() throws Exception {
            ShardTransaction tx;
            if(transaction instanceof DOMStoreReadWriteTransaction) {
                tx = new ShardReadWriteTransaction((DOMStoreReadWriteTransaction)transaction,
                        shardActor, schemaContext, shardStats);
            } else if(transaction instanceof DOMStoreReadTransaction) {
                tx = new ShardReadTransaction((DOMStoreReadTransaction)transaction, shardActor,
                        schemaContext, shardStats);
            } else {
                tx = new ShardWriteTransaction((DOMStoreWriteTransaction)transaction,
                        shardActor, schemaContext, shardStats);
            }

            tx.getContext().setReceiveTimeout(datastoreContext.getShardTransactionIdleTimeout());
            return tx;
        }
    }

    // These classes are in here for test purposes only

    static class GetCompositedModification {
    }


    static class GetCompositeModificationReply {
        private final CompositeModification modification;


        GetCompositeModificationReply(CompositeModification modification) {
            this.modification = modification;
        }


        public CompositeModification getModification() {
            return modification;
        }
    }
}