/*
 * 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.aggregations.metrics.sum;

import org.apache.lucene.index.LeafReaderContext;
import org.elasticsearch.common.lease.Releasables;
import org.elasticsearch.common.util.BigArrays;
import org.elasticsearch.common.util.DoubleArray;
import org.elasticsearch.index.fielddata.SortedNumericDoubleValues;
import org.elasticsearch.search.aggregations.Aggregator;
import org.elasticsearch.search.aggregations.InternalAggregation;
import org.elasticsearch.search.aggregations.LeafBucketCollector;
import org.elasticsearch.search.aggregations.LeafBucketCollectorBase;
import org.elasticsearch.search.aggregations.metrics.NumericMetricsAggregator;
import org.elasticsearch.search.aggregations.pipeline.PipelineAggregator;
import org.elasticsearch.search.aggregations.support.AggregationContext;
import org.elasticsearch.search.aggregations.support.ValuesSource;
import org.elasticsearch.search.aggregations.support.ValuesSourceAggregatorFactory;
import org.elasticsearch.search.aggregations.support.ValuesSourceConfig;
import org.elasticsearch.search.aggregations.support.format.ValueFormatter;

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

/**
 *
 */
public class SumAggregator extends NumericMetricsAggregator.SingleValue {

    final ValuesSource.Numeric valuesSource;
    final ValueFormatter formatter;

    DoubleArray sums;

    public SumAggregator(String name, ValuesSource.Numeric valuesSource, ValueFormatter formatter, AggregationContext context,
            Aggregator parent, List<PipelineAggregator> pipelineAggregators, Map<String, Object> metaData) throws IOException {
        super(name, context, parent, pipelineAggregators, metaData);
        this.valuesSource = valuesSource;
        this.formatter = formatter;
        if (valuesSource != null) {
            sums = context.bigArrays().newDoubleArray(1, true);
        }
    }

    @Override
    public boolean needsScores() {
        return valuesSource != null && valuesSource.needsScores();
    }

    @Override
    public LeafBucketCollector getLeafCollector(LeafReaderContext ctx,
            final LeafBucketCollector sub) throws IOException {
        if (valuesSource == null) {
            return LeafBucketCollector.NO_OP_COLLECTOR;
        }
        final BigArrays bigArrays = context.bigArrays();
        final SortedNumericDoubleValues values = valuesSource.doubleValues(ctx);
        return new LeafBucketCollectorBase(sub, values) {
            @Override
            public void collect(int doc, long bucket) throws IOException {
                sums = bigArrays.grow(sums, bucket + 1);
                values.setDocument(doc);
                final int valuesCount = values.count();
                double sum = 0;
                for (int i = 0; i < valuesCount; i++) {
                    sum += values.valueAt(i);
                }
                sums.increment(bucket, sum);
            }
        };
    }

    @Override
    public double metric(long owningBucketOrd) {
        if (valuesSource == null || owningBucketOrd >= sums.size()) {
            return 0.0;
        }
        return sums.get(owningBucketOrd);
    }

    @Override
    public InternalAggregation buildAggregation(long bucket) {
        if (valuesSource == null || bucket >= sums.size()) {
            return buildEmptyAggregation();
        }
        return new InternalSum(name, sums.get(bucket), formatter, pipelineAggregators(), metaData());
    }

    @Override
    public InternalAggregation buildEmptyAggregation() {
        return new InternalSum(name, 0.0, formatter, pipelineAggregators(), metaData());
    }

    public static class Factory extends ValuesSourceAggregatorFactory.LeafOnly<ValuesSource.Numeric> {

        public Factory(String name, ValuesSourceConfig<ValuesSource.Numeric> valuesSourceConfig) {
            super(name, InternalSum.TYPE.name(), valuesSourceConfig);
        }

        @Override
        protected Aggregator createUnmapped(AggregationContext aggregationContext, Aggregator parent,
                List<PipelineAggregator> pipelineAggregators, Map<String, Object> metaData) throws IOException {
            return new SumAggregator(name, null, config.formatter(), aggregationContext, parent, pipelineAggregators, metaData);
        }

        @Override
        protected Aggregator doCreateInternal(ValuesSource.Numeric valuesSource, AggregationContext aggregationContext, Aggregator parent,
                boolean collectsFromSingleBucket, List<PipelineAggregator> pipelineAggregators, Map<String, Object> metaData)
                throws IOException {
            return new SumAggregator(name, valuesSource, config.formatter(), aggregationContext, parent, pipelineAggregators, metaData);
        }
    }

    @Override
    public void doClose() {
        Releasables.close(sums);
    }
}