/*
 * Copyright (c) 2019 Pantheon Technologies, s.r.o. 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.akka.segjournal;

import static com.google.common.base.Verify.verify;
import static java.util.Objects.requireNonNull;

import akka.actor.ActorSystem;
import akka.actor.ExtendedActorSystem;
import akka.persistence.PersistentRepr;
import com.esotericsoftware.kryo.Kryo;
import com.esotericsoftware.kryo.Serializer;
import com.esotericsoftware.kryo.io.Input;
import com.esotericsoftware.kryo.io.Output;
import com.esotericsoftware.kryo.serializers.JavaSerializer;
import java.util.concurrent.Callable;
import org.opendaylight.controller.akka.segjournal.DataJournalEntry.FromPersistence;
import org.opendaylight.controller.akka.segjournal.DataJournalEntry.ToPersistence;

/**
 * Kryo serializer for {@link DataJournalEntry}. Each {@link SegmentedJournalActor} has its own instance, as well as
 * a nested JavaSerializer to handle the payload.
 *
 * <p>
 * Since we are persisting only parts of {@link PersistentRepr}, this class asymmetric by design:
 * {@link #write(Kryo, Output, DataJournalEntry)} only accepts {@link ToPersistence} subclass, which is a wrapper
 * around a {@link PersistentRepr}, while {@link #read(Kryo, Input, Class)} produces an {@link FromPersistence}, which
 * needs further processing to reconstruct a {@link PersistentRepr}.
 *
 * @author Robert Varga
 */
final class DataJournalEntrySerializer extends Serializer<DataJournalEntry> {
    private final JavaSerializer serializer = new JavaSerializer();
    private final ExtendedActorSystem actorSystem;

    DataJournalEntrySerializer(final ActorSystem actorSystem) {
        this.actorSystem = requireNonNull((ExtendedActorSystem) actorSystem);
    }

    @Override
    public void write(final Kryo kryo, final Output output, final DataJournalEntry object) {
        verify(object instanceof ToPersistence);
        final PersistentRepr repr = ((ToPersistence) object).repr();
        output.writeString(repr.manifest());
        output.writeString(repr.writerUuid());
        serializer.write(kryo, output, repr.payload());
    }

    @Override
    public DataJournalEntry read(final Kryo kryo, final Input input, final Class<DataJournalEntry> type) {
        final String manifest = input.readString();
        final String uuid = input.readString();
        final Object payload = akka.serialization.JavaSerializer.currentSystem().withValue(actorSystem,
            (Callable<Object>)() -> serializer.read(kryo, input, type));
        return new FromPersistence(manifest, uuid, payload);
    }
}