/*
 * Licensed to Elasticsearch under one or more contributor
 * license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright
 * ownership. Elasticsearch 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.elasticsearch.search.facet.datehistogram;

import com.carrotsearch.hppc.LongLongOpenHashMap;
import org.apache.lucene.index.AtomicReaderContext;
import org.apache.lucene.index.SortedNumericDocValues;
import org.elasticsearch.cache.recycler.CacheRecycler;
import org.elasticsearch.common.recycler.Recycler;
import org.elasticsearch.common.rounding.Rounding;
import org.elasticsearch.index.fielddata.IndexNumericFieldData;
import org.elasticsearch.search.facet.FacetExecutor;
import org.elasticsearch.search.facet.InternalFacet;
import org.elasticsearch.search.facet.LongFacetAggregatorBase;

import java.io.IOException;

/**
 * A date histogram facet collector that uses the same field as the key as well as the
 * value.
 */
public class CountDateHistogramFacetExecutor extends FacetExecutor {

    private final Rounding tzRounding;
    private final IndexNumericFieldData indexFieldData;
    final DateHistogramFacet.ComparatorType comparatorType;

    final Recycler.V<LongLongOpenHashMap> counts;

    public CountDateHistogramFacetExecutor(IndexNumericFieldData indexFieldData, Rounding tzRounding, DateHistogramFacet.ComparatorType comparatorType, CacheRecycler cacheRecycler) {
        this.comparatorType = comparatorType;
        this.indexFieldData = indexFieldData;
        this.tzRounding = tzRounding;

        this.counts = cacheRecycler.longLongMap(-1);
    }

    @Override
    public Collector collector() {
        return new Collector();
    }

    @Override
    public InternalFacet buildFacet(String facetName) {
        InternalCountDateHistogramFacet.CountEntry[] countEntries = new InternalCountDateHistogramFacet.CountEntry[counts.v().size()];
        final boolean[] states = counts.v().allocated;
        final long[] keys = counts.v().keys;
        final long[] values = counts.v().values;

        int entryIndex = 0;
        for (int i = 0; i < states.length; i++) {
            if (states[i]) {
                countEntries[entryIndex++] = new InternalCountDateHistogramFacet.CountEntry(keys[i], values[i]);
            }
        }
        counts.close();
        return new InternalCountDateHistogramFacet(facetName, comparatorType, countEntries);
    }

    class Collector extends FacetExecutor.Collector {

        private SortedNumericDocValues values;
        private final DateHistogramProc histoProc;

        public Collector() {
            this.histoProc = new DateHistogramProc(counts.v(), tzRounding);
        }

        @Override
        public void setNextReader(AtomicReaderContext context) throws IOException {
            values = indexFieldData.load(context).getLongValues();
        }

        @Override
        public void collect(int doc) throws IOException {
            histoProc.onDoc(doc, values);
        }

        @Override
        public void postCollection() {
        }
    }

    public static class DateHistogramProc extends LongFacetAggregatorBase {

        private final LongLongOpenHashMap counts;
        private final Rounding tzRounding;

        public DateHistogramProc(LongLongOpenHashMap counts, Rounding tzRounding) {
            this.counts = counts;
            this.tzRounding = tzRounding;
        }

        @Override
        public void onValue(int docId, long value) {
            counts.addTo(tzRounding.round(value), 1);
        }

        public LongLongOpenHashMap counts() {
            return counts;
        }
    }
}