/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.apache.pig.backend.hadoop.executionengine.spark.converter;

import java.io.IOException;
import java.util.List;

import scala.collection.JavaConversions;

import org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperators.POUnion;
import org.apache.pig.backend.hadoop.executionengine.spark.SparkUtil;
import org.apache.pig.data.Tuple;
import org.apache.spark.SparkContext;
import org.apache.spark.rdd.RDD;
import org.apache.spark.rdd.UnionRDD;

public class UnionConverter implements RDDConverter<Tuple, Tuple, POUnion> {

    private final SparkContext sc;

    public UnionConverter(SparkContext sc) {
        this.sc = sc;
    }

    @Override
    public RDD<Tuple> convert(List<RDD<Tuple>> predecessors,
            POUnion physicalOperator) throws IOException {
        SparkUtil.assertPredecessorSizeGreaterThan(predecessors,
                physicalOperator, 0);
        UnionRDD<Tuple> unionRDD = new UnionRDD<Tuple>(sc,
                JavaConversions.asScalaBuffer(predecessors),
                SparkUtil.getManifest(Tuple.class));
        return unionRDD;
    }

}
