/*
 * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
 * or more contributor license agreements. Licensed under the Elastic License
 * 2.0 and the Server Side Public License, v 1; you may not use this file except
 * in compliance with, at your election, the Elastic License 2.0 or the Server
 * Side Public License, v 1.
 */
package org.elasticsearch.search.aggregations.bucket.terms;

import org.elasticsearch.common.io.stream.StreamInput;
import org.elasticsearch.common.io.stream.StreamOutput;
import org.elasticsearch.search.DocValueFormat;
import org.elasticsearch.search.aggregations.AggregationReduceContext;
import org.elasticsearch.search.aggregations.BucketOrder;
import org.elasticsearch.search.aggregations.InternalAggregation;
import org.elasticsearch.search.aggregations.InternalAggregations;
import org.elasticsearch.xcontent.XContentBuilder;

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

/**
 * Result of the {@link TermsAggregator} when the field is some kind of decimal number like a float, double, or distance.
 */
public class DoubleTerms extends InternalMappedTerms<DoubleTerms, DoubleTerms.Bucket> {
    public static final String NAME = "dterms";

    public static class Bucket extends InternalTerms.Bucket<Bucket> {
        double term;

        Bucket(
            double term,
            long docCount,
            InternalAggregations aggregations,
            boolean showDocCountError,
            long docCountError,
            DocValueFormat format
        ) {
            super(docCount, aggregations, showDocCountError, docCountError, format);
            this.term = term;
        }

        /**
         * Read from a stream.
         */
        Bucket(StreamInput in, DocValueFormat format, boolean showDocCountError) throws IOException {
            super(in, format, showDocCountError);
            term = in.readDouble();
        }

        @Override
        protected void writeTermTo(StreamOutput out) throws IOException {
            out.writeDouble(term);
        }

        @Override
        public String getKeyAsString() {
            return format.format(term).toString();
        }

        @Override
        public Object getKey() {
            return term;
        }

        @Override
        public Number getKeyAsNumber() {
            return term;
        }

        @Override
        public int compareKey(Bucket other) {
            return Double.compare(term, other.term);
        }

        @Override
        protected final XContentBuilder keyToXContent(XContentBuilder builder) throws IOException {
            builder.field(CommonFields.KEY.getPreferredName(), term);
            if (format != DocValueFormat.RAW) {
                builder.field(CommonFields.KEY_AS_STRING.getPreferredName(), format.format(term).toString());
            }
            return builder;
        }

        @Override
        public boolean equals(Object obj) {
            return super.equals(obj) && Objects.equals(term, ((Bucket) obj).term);
        }

        @Override
        public int hashCode() {
            return Objects.hash(super.hashCode(), term);
        }
    }

    public DoubleTerms(
        String name,
        BucketOrder reduceOrder,
        BucketOrder order,
        int requiredSize,
        long minDocCount,
        Map<String, Object> metadata,
        DocValueFormat format,
        int shardSize,
        boolean showTermDocCountError,
        long otherDocCount,
        List<Bucket> buckets,
        Long docCountError
    ) {
        super(
            name,
            reduceOrder,
            order,
            requiredSize,
            minDocCount,
            metadata,
            format,
            shardSize,
            showTermDocCountError,
            otherDocCount,
            buckets,
            docCountError
        );
    }

    /**
     * Read from a stream.
     */
    public DoubleTerms(StreamInput in) throws IOException {
        super(in, Bucket::new);
    }

    @Override
    public String getWriteableName() {
        return NAME;
    }

    @Override
    public DoubleTerms create(List<Bucket> buckets) {
        return new DoubleTerms(
            name,
            reduceOrder,
            order,
            requiredSize,
            minDocCount,
            metadata,
            format,
            shardSize,
            showTermDocCountError,
            otherDocCount,
            buckets,
            docCountError
        );
    }

    @Override
    public Bucket createBucket(InternalAggregations aggregations, Bucket prototype) {
        return new Bucket(
            prototype.term,
            prototype.docCount,
            aggregations,
            prototype.showDocCountError,
            prototype.docCountError,
            prototype.format
        );
    }

    @Override
    protected DoubleTerms create(String name, List<Bucket> buckets, BucketOrder reduceOrder, long docCountError, long otherDocCount) {
        return new DoubleTerms(
            name,
            reduceOrder,
            order,
            requiredSize,
            minDocCount,
            getMetadata(),
            format,
            shardSize,
            showTermDocCountError,
            otherDocCount,
            buckets,
            docCountError
        );
    }

    @Override
    public InternalAggregation reduce(List<InternalAggregation> aggregations, AggregationReduceContext reduceContext) {
        boolean promoteToDouble = false;
        for (InternalAggregation agg : aggregations) {
            if (agg instanceof LongTerms
                && (((LongTerms) agg).format == DocValueFormat.RAW || ((LongTerms) agg).format == DocValueFormat.UNSIGNED_LONG_SHIFTED)) {
                /*
                 * this terms agg mixes longs and doubles, we must promote longs to doubles to make the internal aggs
                 * compatible
                 */
                promoteToDouble = true;
                break;
            }
        }
        if (promoteToDouble == false) {
            return super.reduce(aggregations, reduceContext);
        }
        List<InternalAggregation> newAggs = new ArrayList<>(aggregations.size());
        for (InternalAggregation agg : aggregations) {
            if (agg instanceof LongTerms) {
                DoubleTerms dTerms = LongTerms.convertLongTermsToDouble((LongTerms) agg, format);
                newAggs.add(dTerms);
            } else {
                newAggs.add(agg);
            }
        }
        return newAggs.get(0).reduce(newAggs, reduceContext);
    }

    @Override
    protected Bucket createBucket(long docCount, InternalAggregations aggs, long docCountError, DoubleTerms.Bucket prototype) {
        return new Bucket(prototype.term, docCount, aggs, prototype.showDocCountError, docCountError, format);
    }
}
