/*
 * Copyright (c) "Neo4j"
 * Neo4j Sweden AB [http://neo4j.com]
 *
 * This file is part of Neo4j.
 *
 * Neo4j is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.neo4j.internal.recordstorage;

import java.io.IOException;
import java.util.function.Function;
import org.neo4j.storageengine.api.CommandBatchToApply;
import org.neo4j.storageengine.util.IdGeneratorUpdatesWorkSync;
import org.neo4j.storageengine.util.IdUpdateListener;

/**
 * This class wraps several {@link TransactionApplierFactory}s which will do their work sequentially. See also {@link
 * TransactionApplierFacade} which is used to wrap the {@link TransactionApplierFactory#startTx(CommandBatchToApply, BatchContext)} and {@link
 * TransactionApplierFactory#startTx(CommandBatchToApply, BatchContext)} methods.
 * Chains are reused between the batches of transactions as a consequence they should be stateless.
 */
public class TransactionApplierFactoryChain implements TransactionApplierFactory {
    private final Function<IdGeneratorUpdatesWorkSync, IdUpdateListener> idUpdateListenerFunction;
    private final TransactionApplierFactory[] appliers;

    public TransactionApplierFactoryChain(
            Function<IdGeneratorUpdatesWorkSync, IdUpdateListener> idUpdateListenerFunction,
            TransactionApplierFactory... appliers) {
        this.idUpdateListenerFunction = idUpdateListenerFunction;
        this.appliers = appliers;
    }

    public IdUpdateListener getIdUpdateListener(IdGeneratorUpdatesWorkSync idGeneratorUpdatesWorkSync) {
        return idUpdateListenerFunction.apply(idGeneratorUpdatesWorkSync);
    }

    @Override
    public TransactionApplier startTx(CommandBatchToApply transaction, BatchContext batchContext) throws IOException {
        TransactionApplier[] txAppliers = new TransactionApplier[appliers.length];
        for (int i = 0; i < appliers.length; i++) {
            txAppliers[i] = appliers[i].startTx(transaction, batchContext);
        }
        return new TransactionApplierFacade(txAppliers);
    }
}
