/*
 * 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.mapReduceLayer;

import java.io.IOException;
import java.math.BigInteger;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configurable;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.io.WritableComparator;
import org.apache.pig.backend.hadoop.BigIntegerWritable;
import org.apache.pig.impl.io.NullableBigIntegerWritable;
import org.apache.pig.impl.util.ObjectSerializer;

public class PigBigIntegerRawComparator extends WritableComparator implements Configurable {
    private static final Log mLog = LogFactory.getLog(PigBigIntegerRawComparator.class);
    private boolean[] mAsc;
    private final BigIntegerWritable.Comparator mWrappedComp;

    public PigBigIntegerRawComparator() {
        super(NullableBigIntegerWritable.class);
        mWrappedComp = new BigIntegerWritable.Comparator();
    }

    @Override
    public Configuration getConf() {
        return null;
    }

    @Override
    public void setConf(Configuration conf) {
        try {
            mAsc = (boolean[])ObjectSerializer.deserialize(conf.get(
                "pig.sortOrder"));
        } catch (IOException ioe) {
            mLog.error("Unable to deserialize pig.sortOrder "
                    + ioe.getMessage());
            throw new RuntimeException(ioe);
        }
        if (mAsc == null) {
            mAsc = new boolean[1];
            mAsc[0] = true;
        }
    }

    /**
     * Compare two NullableBigIntegerWritables as raw bytes.  If neither are null,
     * then BigIntegerWritable.compare() is used.  If both are null then the indices
     * are compared. Otherwise the null one is defined to be less.
     */
    @Override
    public int compare(byte[] b1, int s1, int l1, byte[] b2, int s2, int l2) {
        int rc = 0;

        // If either are null, handle differently.
        if (b1[s1] == 0 && b2[s2] == 0) {
            rc = mWrappedComp.compare(b1, s1 + 1, l1 - 2, b2, s2 + 1, l2 - 2);
        } else {
            // Two nulls are equal if indices are same
            if (b1[s1] != 0 && b2[s2] != 0) {
                rc = b1[s1 + 1] - b2[s2 + 1];
            }
            else if (b1[s1] != 0) rc = -1;
            else rc = 1;
        }
        if (!mAsc[0]) rc *= -1;
        return rc;
    }

    @Override
    public int compare(Object o1, Object o2) {
        NullableBigIntegerWritable ndw1 = (NullableBigIntegerWritable)o1;
        NullableBigIntegerWritable ndw2 = (NullableBigIntegerWritable)o2;
        int rc = 0;

        // If either are null, handle differently.
        if (!ndw1.isNull() && !ndw2.isNull()) {
            rc = ((BigInteger)ndw1.getValueAsPigType()).compareTo((BigInteger)ndw2.getValueAsPigType());
        } else {
            // Two nulls are equal if indices are same
            if (ndw1.isNull() && ndw2.isNull()) {
                rc = ndw1.getIndex() - ndw2.getIndex();
            }
            else if (ndw1.isNull()) rc = -1;
            else rc = 1;
        }
        if (!mAsc[0]) rc *= -1;
        return rc;
    }
}