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

package org.opensearch.search.aggregations.metrics;

import org.apache.lucene.geo.GeoEncodingUtils;
import org.opensearch.common.geo.GeoPoint;
import org.opensearch.search.aggregations.ParsedAggregation;
import org.opensearch.test.InternalAggregationTestCase;
import org.opensearch.test.geo.RandomGeoGenerator;

import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import static org.hamcrest.Matchers.equalTo;

public class InternalGeoCentroidTests extends InternalAggregationTestCase<InternalGeoCentroid> {

    @Override
    protected InternalGeoCentroid createTestInstance(String name, Map<String, Object> metadata) {
        GeoPoint centroid = RandomGeoGenerator.randomPoint(random());

        // Re-encode lat/longs to avoid rounding issue when testing InternalGeoCentroid#hashCode() and
        // InternalGeoCentroid#equals()
        int encodedLon = GeoEncodingUtils.encodeLongitude(centroid.lon());
        centroid.resetLon(GeoEncodingUtils.decodeLongitude(encodedLon));
        int encodedLat = GeoEncodingUtils.encodeLatitude(centroid.lat());
        centroid.resetLat(GeoEncodingUtils.decodeLatitude(encodedLat));
        long count = randomIntBetween(0, 1000);
        if (count == 0) {
            centroid = null;
        }
        return new InternalGeoCentroid(name, centroid, count, Collections.emptyMap());
    }

    @Override
    protected void assertReduced(InternalGeoCentroid reduced, List<InternalGeoCentroid> inputs) {
        double lonSum = 0;
        double latSum = 0;
        long totalCount = 0;
        for (InternalGeoCentroid input : inputs) {
            if (input.count() > 0) {
                lonSum += (input.count() * input.centroid().getLon());
                latSum += (input.count() * input.centroid().getLat());
            }
            totalCount += input.count();
        }
        if (totalCount > 0) {
            assertEquals(latSum / totalCount, reduced.centroid().getLat(), 1E-5D);
            assertEquals(lonSum / totalCount, reduced.centroid().getLon(), 1E-5D);
        }
        assertEquals(totalCount, reduced.count());
    }

    public void testReduceMaxCount() {
        InternalGeoCentroid maxValueGeoCentroid = new InternalGeoCentroid(
            "agg",
            new GeoPoint(10, 0),
            Long.MAX_VALUE,
            Collections.emptyMap()
        );
        InternalGeoCentroid reducedGeoCentroid = maxValueGeoCentroid.reduce(Collections.singletonList(maxValueGeoCentroid), null);
        assertThat(reducedGeoCentroid.count(), equalTo(Long.MAX_VALUE));
    }

    @Override
    protected void assertFromXContent(InternalGeoCentroid aggregation, ParsedAggregation parsedAggregation) {
        assertTrue(parsedAggregation instanceof ParsedGeoCentroid);
        ParsedGeoCentroid parsed = (ParsedGeoCentroid) parsedAggregation;

        assertEquals(aggregation.centroid(), parsed.centroid());
        assertEquals(aggregation.count(), parsed.count());
    }

    @Override
    protected InternalGeoCentroid mutateInstance(InternalGeoCentroid instance) {
        String name = instance.getName();
        GeoPoint centroid = instance.centroid();
        long count = instance.count();
        Map<String, Object> metadata = instance.getMetadata();
        switch (between(0, 2)) {
            case 0:
                name += randomAlphaOfLength(5);
                break;
            case 1:
                count += between(1, 100);
                if (centroid == null) {
                    // if the new count is > 0 then we need to make sure there is a
                    // centroid or the constructor will throw an exception
                    centroid = new GeoPoint(randomDoubleBetween(-90, 90, false), randomDoubleBetween(-180, 180, false));
                }
                break;
            case 2:
                if (centroid == null) {
                    centroid = new GeoPoint(randomDoubleBetween(-90, 90, false), randomDoubleBetween(-180, 180, false));
                    count = between(1, 100);
                } else {
                    GeoPoint newCentroid = new GeoPoint(centroid);
                    if (randomBoolean()) {
                        newCentroid.resetLat(centroid.getLat() / 2.0);
                    } else {
                        newCentroid.resetLon(centroid.getLon() / 2.0);
                    }
                    centroid = newCentroid;
                }
                break;
            case 3:
                if (metadata == null) {
                    metadata = new HashMap<>(1);
                } else {
                    metadata = new HashMap<>(instance.getMetadata());
                }
                metadata.put(randomAlphaOfLength(15), randomInt());
                break;
            default:
                throw new AssertionError("Illegal randomisation branch");
        }
        return new InternalGeoCentroid(name, centroid, count, metadata);
    }
}