/*
 * 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.lucene.search.comparators;

import org.apache.lucene.document.LongPoint;
import org.apache.lucene.index.LeafReaderContext;
import org.apache.lucene.search.LeafFieldComparator;

import java.io.IOException;

Comparator based on Long.compare for numHits. This comparator provides a skipping functionality – an iterator that can skip over non-competitive documents. /**
 * Comparator based on {@link Long#compare} for {@code numHits}.
 * This comparator provides a skipping functionality – an iterator that can skip over non-competitive documents.
 */
public class LongComparator extends NumericComparator<Long> {
    private final long[] values;
    protected long topValue;
    protected long bottom;

    public LongComparator(int numHits, String field, Long missingValue, boolean reverse, int sortPos) {
        super(field,missingValue != null ? missingValue : 0L, reverse, sortPos, Long.BYTES);
        values = new long[numHits];
    }

    @Override
    public int compare(int slot1, int slot2) {
        return Long.compare(values[slot1], values[slot2]);
    }

    @Override
    public void setTopValue(Long value) {
        super.setTopValue(value);
        topValue = value;
    }

    @Override
    public Long value(int slot) {
        return Long.valueOf(values[slot]);
    }

    @Override
    public LeafFieldComparator getLeafComparator(LeafReaderContext context) throws IOException {
        return new LongLeafComparator(context);
    }

    
Leaf comparator for LongComparator that provides skipping functionality /**
     * Leaf comparator for {@link LongComparator} that provides skipping functionality
     */
    public class LongLeafComparator extends NumericLeafComparator {

        public LongLeafComparator(LeafReaderContext context) throws IOException {
            super(context);
        }

        private long getValueForDoc(int doc) throws IOException {
            if (docValues.advanceExact(doc)) {
                return docValues.longValue();
            } else {
                return missingValue;
            }
        }

        @Override
        public void setBottom(int slot) throws IOException {
            bottom = values[slot];
            super.setBottom(slot);
        }

        @Override
        public int compareBottom(int doc) throws IOException {
            return Long.compare(bottom, getValueForDoc(doc));
        }

        @Override
        public int compareTop(int doc) throws IOException {
            return Long.compare(topValue, getValueForDoc(doc));
        }

        @Override
        public void copy(int slot, int doc) throws IOException {
            values[slot] = getValueForDoc(doc);
            super.copy(slot, doc);
        }

        @Override
        protected boolean isMissingValueCompetitive() {
            int result = Long.compare(missingValue, bottom);
            // in reverse (desc) sort missingValue is competitive when it's greater or equal to bottom,
            // in asc sort missingValue is competitive when it's smaller or equal to bottom
            return reverse ? (result >= 0) : (result <= 0);
        }

        @Override
        protected void encodeBottom(byte[] packedValue) {
            LongPoint.encodeDimension(bottom, packedValue, 0);
        }

        @Override
        protected void encodeTop(byte[] packedValue) {
            LongPoint.encodeDimension(topValue, packedValue, 0);
        }
    }

}