/*
 * SPDX-License-Identifier: Apache-2.0
 *
 * The OpenSearch Contributors require contributions made to
 * this file be licensed under the Apache-2.0 license or a
 * compatible open source license.
 */

/*
 * 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.
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/*
 * Modifications Copyright OpenSearch Contributors. See
 * GitHub history for details.
 */

package org.opensearch.join.aggregations;

import org.apache.lucene.search.Query;
import org.opensearch.index.query.QueryShardContext;
import org.opensearch.search.aggregations.AggregationExecutionException;
import org.opensearch.search.aggregations.Aggregator;
import org.opensearch.search.aggregations.AggregatorFactories;
import org.opensearch.search.aggregations.AggregatorFactory;
import org.opensearch.search.aggregations.CardinalityUpperBound;
import org.opensearch.search.aggregations.InternalAggregation;
import org.opensearch.search.aggregations.NonCollectingAggregator;
import org.opensearch.search.aggregations.support.ValuesSource;
import org.opensearch.search.aggregations.support.ValuesSource.Bytes.WithOrdinals;
import org.opensearch.search.aggregations.support.ValuesSourceAggregatorFactory;
import org.opensearch.search.aggregations.support.ValuesSourceConfig;
import org.opensearch.search.internal.SearchContext;

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

import static org.opensearch.search.aggregations.support.AggregationUsageService.OTHER_SUBTYPE;

public class ChildrenAggregatorFactory extends ValuesSourceAggregatorFactory {

    private final Query parentFilter;
    private final Query childFilter;

    public ChildrenAggregatorFactory(
        String name,
        ValuesSourceConfig config,
        Query childFilter,
        Query parentFilter,
        QueryShardContext context,
        AggregatorFactory parent,
        AggregatorFactories.Builder subFactoriesBuilder,
        Map<String, Object> metadata
    ) throws IOException {
        super(name, config, context, parent, subFactoriesBuilder, metadata);

        this.childFilter = childFilter;
        this.parentFilter = parentFilter;
    }

    @Override
    protected Aggregator createUnmapped(SearchContext searchContext, Aggregator parent, Map<String, Object> metadata) throws IOException {
        return new NonCollectingAggregator(name, searchContext, parent, factories, metadata) {
            @Override
            public InternalAggregation buildEmptyAggregation() {
                return new InternalChildren(name, 0, buildEmptySubAggregations(), metadata());
            }
        };
    }

    @Override
    protected Aggregator doCreateInternal(
        SearchContext searchContext,
        Aggregator parent,
        CardinalityUpperBound cardinality,
        Map<String, Object> metadata
    ) throws IOException {

        ValuesSource rawValuesSource = config.getValuesSource();
        if (!(rawValuesSource instanceof WithOrdinals valuesSource)) {
            throw new AggregationExecutionException(
                "ValuesSource type " + rawValuesSource.toString() + "is not supported for aggregation " + this.name()
            );
        }
        long maxOrd = valuesSource.globalMaxOrd(searchContext.searcher());
        return new ParentToChildrenAggregator(
            name,
            factories,
            searchContext,
            parent,
            childFilter,
            parentFilter,
            valuesSource,
            maxOrd,
            cardinality,
            metadata
        );
    }

    @Override
    public String getStatsSubtype() {
        // Child Aggregation is registered in non-standard way, so it might return child's values type
        return OTHER_SUBTYPE;
    }

    @Override
    protected boolean supportsConcurrentSegmentSearch() {
        return true;
    }
}
