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/*
 * Copyright 2016 Christoph Böhme
 *
 * Licensed under the Apache License, Version 2.0 the "License";
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.metafacture.plumbing;

import org.metafacture.framework.FluxCommand;
import org.metafacture.framework.StreamReceiver;
import org.metafacture.framework.annotations.Description;
import org.metafacture.framework.annotations.In;
import org.metafacture.framework.annotations.Out;
import org.metafacture.framework.helpers.DefaultStreamPipe;

/**
 * Merges a sequence of {@link #setBatchSize(long)} records. On a
 * close-stream event, a record containing fewer source records may be
 * created.
 *
 * @author Christoph Böhme
 *
 */
@Description("Merges a sequence of batchSize records")
@In(StreamReceiver.class)
@Out(StreamReceiver.class)
@FluxCommand("merge-batch-stream")
public final class StreamBatchMerger extends DefaultStreamPipe {

    /**
     * The default value for {@link #setBatchSize(long)}.
     */
    public static final long DEFAULT_BATCH_SIZE = 1;

    private long batchSize = DEFAULT_BATCH_SIZE;
    private long recordCount;

    /**
     * Creates an instance of {@link StreamBatchMerger}.
     */
    public StreamBatchMerger() {
    }

    /**
     * Sets the number of records that should be merged into a batch.
     * 
     * The default batch size is 1, wich means that no records are merged.
     * 
     * This parameter must not be changed during processing.
     *
     * @param batchSize the number of records that should be merged.
     */
    public void setBatchSize(final long batchSize) {
        this.batchSize = batchSize;
    }

    /**
     * Gets the batch size.
     *
     * @return the batch size.
     */
    public long getBatchSize() {
        return batchSize;
    }

    @Override
    public void startRecord(final String identifier) {
        if (recordCount == 0) {
            getReceiver().startRecord(identifier);
        }
        recordCount += 1;
    }

    @Override
    public void endRecord() {
        if (recordCount >= batchSize) {
            getReceiver().endRecord();
            recordCount = 0;
        }
    }

    @Override
    public void startEntity(final String name) {
        getReceiver().startEntity(name);
    }

    @Override
    public void endEntity() {
        getReceiver().endEntity();
    }

    @Override
    public void literal(final String name, final String value) {
        getReceiver().literal(name, value);
    }

    @Override
    protected void onResetStream() {
        recordCount = 0;
    }

    @Override
    protected void onCloseStream() {
        if (recordCount > 0) {
            getReceiver().endRecord();
            recordCount = 0;
        }
    }

}