/*
 * 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.bucket.sampler;

import org.apache.lucene.document.Document;
import org.apache.lucene.document.DoubleDocValuesField;
import org.apache.lucene.document.Field;
import org.apache.lucene.document.NumericDocValuesField;
import org.apache.lucene.document.SortedDocValuesField;
import org.apache.lucene.document.StringField;
import org.apache.lucene.document.TextField;
import org.apache.lucene.index.DirectoryReader;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.IndexWriterConfig;
import org.apache.lucene.index.LogDocMergePolicy;
import org.apache.lucene.search.MatchAllDocsQuery;
import org.apache.lucene.store.Directory;
import org.apache.lucene.tests.analysis.MockAnalyzer;
import org.apache.lucene.tests.index.RandomIndexWriter;
import org.apache.lucene.tests.util.LuceneTestCase;
import org.apache.lucene.util.BytesRef;
import org.elasticsearch.common.lucene.search.function.FieldValueFactorFunction;
import org.elasticsearch.common.lucene.search.function.FunctionScoreQuery;
import org.elasticsearch.index.fielddata.IndexNumericFieldData;
import org.elasticsearch.index.fielddata.ScriptDocValues.Doubles;
import org.elasticsearch.index.fielddata.ScriptDocValues.DoublesSupplier;
import org.elasticsearch.index.fielddata.plain.SortedDoublesIndexFieldData;
import org.elasticsearch.index.mapper.KeywordFieldMapper;
import org.elasticsearch.index.mapper.MappedFieldType;
import org.elasticsearch.index.mapper.NumberFieldMapper;
import org.elasticsearch.script.field.DelegateDocValuesField;
import org.elasticsearch.search.aggregations.AggregatorTestCase;
import org.elasticsearch.search.aggregations.bucket.terms.Terms;
import org.elasticsearch.search.aggregations.bucket.terms.TermsAggregationBuilder;
import org.elasticsearch.search.aggregations.support.CoreValuesSourceType;

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

import static org.hamcrest.Matchers.greaterThan;

public class DiversifiedSamplerTests extends AggregatorTestCase {

    private void writeBooks(RandomIndexWriter iw) throws IOException {
        String data[] = {
            // "id,cat,name,price,inStock,author_t,series_t,sequence_i,genre_s,genre_id",
            "0553573403,book,A Game of Thrones,7.99,true,George R.R. Martin,A Song of Ice and Fire,1,fantasy,0",
            "0553579908,book,A Clash of Kings,7.99,true,George R.R. Martin,A Song of Ice and Fire,2,fantasy,0",
            "055357342X,book,A Storm of Swords,7.99,true,George R.R. Martin,A Song of Ice and Fire,3,fantasy,0",
            "0553293354,book,Foundation,17.99,true,Isaac Asimov,Foundation Novels,1,scifi,1",
            "0812521390,book,The Black Company,6.99,false,Glen Cook,The Chronicles of The Black Company,1,fantasy,0",
            "0812550706,book,Ender's Game,6.99,true,Orson Scott Card,Ender,1,scifi,1",
            "0441385532,book,Jhereg,7.95,false,Steven Brust,Vlad Taltos,1,fantasy,0",
            "0380014300,book,Nine Princes In Amber,6.99,true,Roger Zelazny,the Chronicles of Amber,1,fantasy,0",
            "0805080481,book,The Book of Three,5.99,true,Lloyd Alexander,The Chronicles of Prydain,1,fantasy,0",
            "080508049X,book,The Black Cauldron,5.99,true,Lloyd Alexander,The Chronicles of Prydain,2,fantasy,0" };

        List<Document> docs = new ArrayList<>();
        for (String entry : data) {
            String[] parts = entry.split(",");
            Document document = new Document();
            document.add(new SortedDocValuesField("id", new BytesRef(parts[0])));
            document.add(new StringField("cat", parts[1], Field.Store.NO));
            document.add(new TextField("name", parts[2], Field.Store.NO));
            document.add(new DoubleDocValuesField("price", Double.valueOf(parts[3])));
            document.add(new StringField("inStock", parts[4], Field.Store.NO));
            document.add(new StringField("author", parts[5], Field.Store.NO));
            document.add(new StringField("series", parts[6], Field.Store.NO));
            document.add(new StringField("sequence", parts[7], Field.Store.NO));
            document.add(new SortedDocValuesField("genre", new BytesRef(parts[8])));
            document.add(new NumericDocValuesField("genre_id", Long.valueOf(parts[9])));
            docs.add(document);
        }
        /*
         * Add all documents at once to force the test to aggregate all
         * values together at the same time. *That* is required because
         * the tests assume that all books are on a shard together. And
         * they aren't always if they end up in separate leaves.
         */
        iw.addDocuments(docs);
    }

    public void testDiversifiedSampler() throws Exception {
        Directory directory = newDirectory();
        IndexWriterConfig iwc = LuceneTestCase.newIndexWriterConfig(random(), new MockAnalyzer(random()));
        iwc.setMergePolicy(new LogDocMergePolicy());
        RandomIndexWriter indexWriter = new RandomIndexWriter(random(), directory, iwc);
        MappedFieldType genreFieldType = new KeywordFieldMapper.KeywordFieldType("genre");
        writeBooks(indexWriter);
        indexWriter.close();
        DirectoryReader indexReader = DirectoryReader.open(directory);
        Consumer<InternalSampler> verify = result -> {
            Terms terms = result.getAggregations().get("terms");
            assertEquals(2, terms.getBuckets().size());
            assertEquals("0805080481", terms.getBuckets().get(0).getKeyAsString());
            assertEquals("0812550706", terms.getBuckets().get(1).getKeyAsString());
        };
        testCase(indexReader, genreFieldType, "map", verify);
        testCase(indexReader, genreFieldType, "global_ordinals", verify);
        testCase(indexReader, genreFieldType, "bytes_hash", verify);

        genreFieldType = new NumberFieldMapper.NumberFieldType("genre_id", NumberFieldMapper.NumberType.LONG);
        testCase(indexReader, genreFieldType, null, verify);

        // wrong field:
        genreFieldType = new KeywordFieldMapper.KeywordFieldType("wrong_field");
        testCase(indexReader, genreFieldType, null, result -> {
            Terms terms = result.getAggregations().get("terms");
            assertEquals(1, terms.getBuckets().size());
            assertEquals("0805080481", terms.getBuckets().get(0).getKeyAsString());
        });

        indexReader.close();
        directory.close();
    }

    public void testRidiculousSize() throws Exception {
        Directory directory = newDirectory();
        RandomIndexWriter indexWriter = new RandomIndexWriter(random(), directory);
        writeBooks(indexWriter);
        indexWriter.close();
        DirectoryReader indexReader = DirectoryReader.open(directory);

        MappedFieldType genreFieldType = new KeywordFieldMapper.KeywordFieldType("genre");
        Consumer<InternalSampler> verify = result -> {
            Terms terms = result.getAggregations().get("terms");
            assertThat(terms.getBuckets().size(), greaterThan(0));
        };

        try {
            // huge shard_size
            testCase(indexReader, genreFieldType, "map", verify, Integer.MAX_VALUE, 1);
            testCase(indexReader, genreFieldType, "global_ordinals", verify, Integer.MAX_VALUE, 1);
            testCase(indexReader, genreFieldType, "bytes_hash", verify, Integer.MAX_VALUE, 1);

            // huge maxDocsPerValue
            testCase(indexReader, genreFieldType, "map", verify, 100, Integer.MAX_VALUE);
            testCase(indexReader, genreFieldType, "global_ordinals", verify, 100, Integer.MAX_VALUE);
            testCase(indexReader, genreFieldType, "bytes_hash", verify, 100, Integer.MAX_VALUE);
        } finally {
            indexReader.close();
            directory.close();
        }
    }

    private void testCase(IndexReader indexReader, MappedFieldType genreFieldType, String executionHint, Consumer<InternalSampler> verify)
        throws IOException {
        testCase(indexReader, genreFieldType, executionHint, verify, 100, 1);
    }

    private void testCase(
        IndexReader indexReader,
        MappedFieldType genreFieldType,
        String executionHint,
        Consumer<InternalSampler> verify,
        int shardSize,
        int maxDocsPerValue
    ) throws IOException {
        MappedFieldType idFieldType = new KeywordFieldMapper.KeywordFieldType("id");

        SortedDoublesIndexFieldData fieldData = new SortedDoublesIndexFieldData(
            "price",
            IndexNumericFieldData.NumericType.DOUBLE,
            CoreValuesSourceType.NUMERIC,
            (dv, n) -> new DelegateDocValuesField(new Doubles(new DoublesSupplier(dv)), n),
            false
        );
        FunctionScoreQuery query = new FunctionScoreQuery(
            new MatchAllDocsQuery(),
            new FieldValueFactorFunction("price", 1, FieldValueFactorFunction.Modifier.RECIPROCAL, null, fieldData)
        );

        DiversifiedAggregationBuilder builder = new DiversifiedAggregationBuilder("_name").field(genreFieldType.name())
            .executionHint(executionHint)
            .maxDocsPerValue(maxDocsPerValue)
            .shardSize(shardSize)
            .subAggregation(new TermsAggregationBuilder("terms").field("id"));

        InternalSampler result = searchAndReduce(indexReader, new AggTestConfig(builder, genreFieldType, idFieldType).withQuery(query));
        verify.accept(result);
    }

    public void testDiversifiedSampler_noDocs() throws Exception {
        Directory directory = newDirectory();
        RandomIndexWriter indexWriter = new RandomIndexWriter(random(), directory);
        indexWriter.close();
        IndexReader indexReader = DirectoryReader.open(directory);

        MappedFieldType idFieldType = new KeywordFieldMapper.KeywordFieldType("id");

        MappedFieldType genreFieldType = new KeywordFieldMapper.KeywordFieldType("genre");

        DiversifiedAggregationBuilder builder = new DiversifiedAggregationBuilder("_name").field(genreFieldType.name())
            .subAggregation(new TermsAggregationBuilder("terms").field("id"));

        InternalSampler result = searchAndReduce(indexReader, new AggTestConfig(builder, genreFieldType, idFieldType));
        Terms terms = result.getAggregations().get("terms");
        assertEquals(0, terms.getBuckets().size());
        indexReader.close();
        directory.close();
    }

    public void testSupportsParallelCollection() {
        DiversifiedAggregationBuilder sampler = new DiversifiedAggregationBuilder("name");
        if (randomBoolean()) {
            sampler.field("field");
        }
        if (randomBoolean()) {
            sampler.maxDocsPerValue(randomIntBetween(1, 1000));
        }
        if (randomBoolean()) {
            sampler.subAggregation(new TermsAggregationBuilder("name").field("field"));
        }
        if (randomBoolean()) {
            sampler.shardSize(randomIntBetween(1, 1000));
        }
        assertFalse(sampler.supportsParallelCollection(null));
    }
}