/*
 * 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.io.Serializable;
import java.util.Iterator;
import java.util.List;

import scala.runtime.AbstractFunction1;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.pig.backend.executionengine.ExecException;
import org.apache.pig.backend.hadoop.executionengine.physicalLayer.POStatus;
import org.apache.pig.backend.hadoop.executionengine.physicalLayer.Result;
import org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperators.POPackage;
import org.apache.pig.backend.hadoop.executionengine.spark.SparkUtil;
import org.apache.pig.data.Tuple;
import org.apache.pig.impl.io.NullableTuple;
import org.apache.pig.impl.io.PigNullableWritable;
import org.apache.spark.rdd.RDD;

@SuppressWarnings({ "serial" })
public class PackageConverter implements RDDConverter<Tuple, Tuple, POPackage> {
    private static final Log LOG = LogFactory.getLog(PackageConverter.class);

    @Override
    public RDD<Tuple> convert(List<RDD<Tuple>> predecessors,
            POPackage physicalOperator) throws IOException {
        SparkUtil.assertPredecessorSize(predecessors, physicalOperator, 1);
        RDD<Tuple> rdd = predecessors.get(0);
        // package will generate the group from the result of the local
        // rearrange
        return rdd.map(new PackageFunction(physicalOperator),
                SparkUtil.getManifest(Tuple.class));
    }

    private static class PackageFunction extends
            AbstractFunction1<Tuple, Tuple> implements Serializable {

        private final POPackage physicalOperator;

        public PackageFunction(POPackage physicalOperator) {
            this.physicalOperator = physicalOperator;
        }

        @Override
        public Tuple apply(final Tuple t) {
            // (key, Seq<Tuple>:{(index, key, value without key)})
            if (LOG.isDebugEnabled())
                LOG.debug("PackageFunction in " + t);
            Result result;
            try {
                PigNullableWritable key = new PigNullableWritable() {

                    public Object getValueAsPigType() {
                        try {
                            Object keyTuple = t.get(0);
                            return keyTuple;
                        } catch (ExecException e) {
                            throw new RuntimeException(e);
                        }
                    }
                };
                final Iterator<Tuple> bagIterator = (Iterator<Tuple>) t.get(1);
                Iterator<NullableTuple> iterator = new Iterator<NullableTuple>() {
                    public boolean hasNext() {
                        return bagIterator.hasNext();
                    }

                    public NullableTuple next() {
                        try {
                            // we want the value and index only
                            Tuple next = bagIterator.next();
                            NullableTuple nullableTuple = new NullableTuple(
                                    (Tuple) next.get(1));
                            nullableTuple.setIndex(((Number) next.get(0))
                                    .byteValue());
                            if (LOG.isDebugEnabled())
                                LOG.debug("Setting index to " + next.get(0) +
                                    " for tuple " + (Tuple)next.get(1));
                            return nullableTuple;
                        } catch (ExecException e) {
                            throw new RuntimeException(e);
                        }
                    }

                    public void remove() {
                        throw new UnsupportedOperationException();
                    }
                };
                physicalOperator.setInputs(null);
                physicalOperator.attachInput(key, iterator);
                result = physicalOperator.getNextTuple();
            } catch (ExecException e) {
                throw new RuntimeException(
                        "Couldn't do Package on tuple: " + t, e);
            }

            if (result == null) {
                throw new RuntimeException(
                        "Null response found for Package on tuple: " + t);
            }
            Tuple out;
            switch (result.returnStatus) {
            case POStatus.STATUS_OK:
                // (key, {(value)...})
                if (LOG.isDebugEnabled())
                    LOG.debug("PackageFunction out " + result.result);
                out = (Tuple) result.result;
                break;
            case POStatus.STATUS_NULL:
                out = null;
                break;
            default:
                throw new RuntimeException(
                        "Unexpected response code from operator "
                                + physicalOperator + " : " + result + " "
                                + result.returnStatus);
            }
            if (LOG.isDebugEnabled())
                LOG.debug("PackageFunction out " + out);
            return out;
        }
    }

}