/*
 * 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", the "GNU Affero General Public License v3.0 only", 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", the "GNU Affero General Public
 * License v3.0 only", or the "Server Side Public License, v 1".
 */

package org.elasticsearch.search.aggregations.metrics;

import org.apache.lucene.document.LongPoint;
import org.apache.lucene.document.NumericDocValuesField;
import org.apache.lucene.document.SortedNumericDocValuesField;
import org.apache.lucene.search.FieldExistsQuery;
import org.apache.lucene.search.MatchAllDocsQuery;
import org.apache.lucene.search.Query;
import org.apache.lucene.tests.index.RandomIndexWriter;
import org.elasticsearch.core.CheckedConsumer;
import org.elasticsearch.index.mapper.MappedFieldType;
import org.elasticsearch.index.mapper.NumberFieldMapper;
import org.elasticsearch.search.aggregations.AggregationBuilder;
import org.elasticsearch.search.aggregations.AggregatorTestCase;
import org.elasticsearch.search.aggregations.support.AggregationInspectionHelper;
import org.elasticsearch.search.aggregations.support.CoreValuesSourceType;
import org.elasticsearch.search.aggregations.support.ValuesSourceType;

import java.io.IOException;
import java.util.List;
import java.util.function.Consumer;

import static java.util.Arrays.asList;
import static java.util.Collections.singleton;
import static org.elasticsearch.search.aggregations.AggregationBuilders.percentiles;
import static org.hamcrest.Matchers.equalTo;

public class TDigestPercentilesAggregatorTests extends AggregatorTestCase {

    @Override
    protected AggregationBuilder createAggBuilderForTypeTest(MappedFieldType fieldType, String fieldName) {
        var tdigestConfig = new PercentilesConfig.TDigest();
        if (randomBoolean()) {
            tdigestConfig.setCompression(randomDoubleBetween(50, 200, true));
        }
        if (randomBoolean()) {
            tdigestConfig.parseExecutionHint(randomFrom(TDigestExecutionHint.values()).toString());
        }
        return new PercentilesAggregationBuilder("tdist_percentiles").field(fieldName).percentilesConfig(tdigestConfig);
    }

    @Override
    protected List<ValuesSourceType> getSupportedValuesSourceTypes() {
        return List.of(CoreValuesSourceType.NUMERIC, CoreValuesSourceType.DATE, CoreValuesSourceType.BOOLEAN);
    }

    public void testNoDocs() throws IOException {
        testCase(new MatchAllDocsQuery(), iw -> {
            // Intentionally not writing any docs
        }, tdigest -> {
            assertEquals(0L, tdigest.getState().size());
            assertFalse(AggregationInspectionHelper.hasValue(tdigest));
        });
    }

    public void testNoMatchingField() throws IOException {
        testCase(new MatchAllDocsQuery(), iw -> {
            iw.addDocument(singleton(new SortedNumericDocValuesField("wrong_number", 7)));
            iw.addDocument(singleton(new SortedNumericDocValuesField("wrong_number", 1)));
        }, tdigest -> {
            assertEquals(0L, tdigest.getState().size());
            assertFalse(AggregationInspectionHelper.hasValue(tdigest));
        });
    }

    public void testSomeMatchesSortedNumericDocValues() throws IOException {
        testCase(new FieldExistsQuery("number"), iw -> {
            iw.addDocument(singleton(new SortedNumericDocValuesField("number", 8)));
            iw.addDocument(singleton(new SortedNumericDocValuesField("number", 5)));
            iw.addDocument(singleton(new SortedNumericDocValuesField("number", 3)));
            iw.addDocument(singleton(new SortedNumericDocValuesField("number", 2)));
            iw.addDocument(singleton(new SortedNumericDocValuesField("number", 1)));
            iw.addDocument(singleton(new SortedNumericDocValuesField("number", 1)));
            iw.addDocument(singleton(new SortedNumericDocValuesField("number", 0)));
        }, tdigest -> {
            assertEquals(7L, tdigest.getState().size());
            assertEquals(7L, tdigest.getState().centroidCount());
            assertEquals(4.0d, tdigest.percentile(75), 0.0d);
            assertEquals("4.0", tdigest.percentileAsString(75));
            assertEquals(2.0d, tdigest.percentile(50), 0.0d);
            assertEquals("2.0", tdigest.percentileAsString(50));
            assertEquals(1.0d, tdigest.percentile(22), 0.0d);
            assertEquals("1.0", tdigest.percentileAsString(22));
            assertTrue(AggregationInspectionHelper.hasValue(tdigest));
        });
    }

    public void testSomeMatchesNumericDocValues() throws IOException {
        testCase(new FieldExistsQuery("number"), iw -> {
            iw.addDocument(singleton(new NumericDocValuesField("number", 8)));
            iw.addDocument(singleton(new NumericDocValuesField("number", 5)));
            iw.addDocument(singleton(new NumericDocValuesField("number", 3)));
            iw.addDocument(singleton(new NumericDocValuesField("number", 2)));
            iw.addDocument(singleton(new NumericDocValuesField("number", 1)));
            iw.addDocument(singleton(new NumericDocValuesField("number", 1)));
            iw.addDocument(singleton(new NumericDocValuesField("number", 0)));
        }, tdigest -> {
            assertEquals(tdigest.getState().size(), 7L);
            assertEquals(tdigest.getState().centroidCount(), 7L);
            assertEquals(8.0d, tdigest.percentile(100), 0.0d);
            assertEquals("8.0", tdigest.percentileAsString(100));
            assertEquals(4.0d, tdigest.percentile(75), 0.0d);
            assertEquals("4.0", tdigest.percentileAsString(75));
            assertEquals(1.0d, tdigest.percentile(33), 0.0d);
            assertEquals("1.0", tdigest.percentileAsString(33));
            assertEquals(1.0d, tdigest.percentile(25), 0.0d);
            assertEquals("1.0", tdigest.percentileAsString(25));
            assertEquals(0.06d, tdigest.percentile(1), 0.0d);
            assertEquals("0.06", tdigest.percentileAsString(1));
            assertTrue(AggregationInspectionHelper.hasValue(tdigest));
        });
    }

    public void testQueryFiltering() throws IOException {
        final CheckedConsumer<RandomIndexWriter, IOException> docs = iw -> {
            iw.addDocument(asList(new LongPoint("row", 7), new SortedNumericDocValuesField("number", 8)));
            iw.addDocument(asList(new LongPoint("row", 6), new SortedNumericDocValuesField("number", 5)));
            iw.addDocument(asList(new LongPoint("row", 5), new SortedNumericDocValuesField("number", 3)));
            iw.addDocument(asList(new LongPoint("row", 4), new SortedNumericDocValuesField("number", 2)));
            iw.addDocument(asList(new LongPoint("row", 3), new SortedNumericDocValuesField("number", 1)));
            iw.addDocument(asList(new LongPoint("row", 2), new SortedNumericDocValuesField("number", 1)));
            iw.addDocument(asList(new LongPoint("row", 1), new SortedNumericDocValuesField("number", 0)));
        };

        testCase(LongPoint.newRangeQuery("row", 1, 4), docs, tdigest -> {
            assertEquals(4L, tdigest.getState().size());
            assertEquals(4L, tdigest.getState().centroidCount());
            assertEquals(2.0d, tdigest.percentile(100), 0.0d);
            assertEquals(1.0d, tdigest.percentile(50), 0.0d);
            assertEquals(0.75d, tdigest.percentile(25), 0.0d);
            assertTrue(AggregationInspectionHelper.hasValue(tdigest));
        });

        testCase(LongPoint.newRangeQuery("row", 100, 110), docs, tdigest -> {
            assertEquals(0L, tdigest.getState().size());
            assertEquals(0L, tdigest.getState().centroidCount());
            assertFalse(AggregationInspectionHelper.hasValue(tdigest));
        });
    }

    public void testTdigestThenHdrSettings() throws Exception {
        int sigDigits = randomIntBetween(1, 5);
        IllegalArgumentException e = expectThrows(IllegalArgumentException.class, () -> {
            percentiles("percentiles").compression(100.0)
                .method(PercentilesMethod.TDIGEST)
                .numberOfSignificantValueDigits(sigDigits) // <-- this should trigger an exception
                .field("value");
        });
        assertThat(
            e.getMessage(),
            equalTo("Cannot set [numberOfSignificantValueDigits] because the " + "method has already been configured for TDigest")
        );
    }

    private void testCase(
        Query query,
        CheckedConsumer<RandomIndexWriter, IOException> buildIndex,
        Consumer<InternalTDigestPercentiles> verify
    ) throws IOException {
        PercentilesAggregationBuilder builder;
        // TODO this randomization path should be removed when the old settings are removed
        if (randomBoolean()) {
            builder = new PercentilesAggregationBuilder("test").field("number").method(PercentilesMethod.TDIGEST);
        } else {
            PercentilesConfig hdr = new PercentilesConfig.TDigest();
            builder = new PercentilesAggregationBuilder("test").field("number").percentilesConfig(hdr);
        }

        MappedFieldType fieldType = new NumberFieldMapper.NumberFieldType("number", NumberFieldMapper.NumberType.LONG);
        testCase(buildIndex, verify, new AggTestConfig(builder, fieldType).withQuery(query));
    }
}