/*
 * 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.search.collapse;

import org.apache.lucene.tests.analysis.MockAnalyzer;
import org.apache.lucene.index.DirectoryReader;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.IndexWriter;
import org.apache.lucene.search.Query;
import org.apache.lucene.store.ByteBuffersDirectory;
import org.apache.lucene.store.Directory;
import org.opensearch.core.common.io.stream.NamedWriteableRegistry;
import org.opensearch.core.common.io.stream.Writeable;
import org.opensearch.common.settings.Settings;
import org.opensearch.core.xcontent.NamedXContentRegistry;
import org.opensearch.core.xcontent.XContentParser;
import org.opensearch.index.mapper.KeywordFieldMapper;
import org.opensearch.index.mapper.MappedFieldType;
import org.opensearch.index.mapper.NumberFieldMapper;
import org.opensearch.index.mapper.TextSearchInfo;
import org.opensearch.index.mapper.ValueFetcher;
import org.opensearch.index.query.InnerHitBuilder;
import org.opensearch.index.query.InnerHitBuilderTests;
import org.opensearch.index.query.QueryShardContext;
import org.opensearch.search.SearchModule;
import org.opensearch.search.lookup.SearchLookup;
import org.opensearch.test.AbstractSerializingTestCase;
import org.junit.AfterClass;
import org.junit.BeforeClass;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

import static java.util.Collections.emptyList;
import static org.mockito.Mockito.mock;
import static org.mockito.Mockito.when;

public class CollapseBuilderTests extends AbstractSerializingTestCase<CollapseBuilder> {
    private static NamedWriteableRegistry namedWriteableRegistry;
    private static NamedXContentRegistry xContentRegistry;

    @BeforeClass
    public static void init() {
        SearchModule searchModule = new SearchModule(Settings.EMPTY, emptyList());
        namedWriteableRegistry = new NamedWriteableRegistry(searchModule.getNamedWriteables());
        xContentRegistry = new NamedXContentRegistry(searchModule.getNamedXContents());
    }

    @AfterClass
    public static void afterClass() {
        namedWriteableRegistry = null;
        xContentRegistry = null;
    }

    public static CollapseBuilder randomCollapseBuilder() {
        return randomCollapseBuilder(true);
    }

    public static CollapseBuilder randomCollapseBuilder(boolean multiInnerHits) {
        CollapseBuilder builder = new CollapseBuilder(randomAlphaOfLength(10));
        builder.setMaxConcurrentGroupRequests(randomIntBetween(1, 48));
        int numInnerHits = randomIntBetween(0, multiInnerHits ? 5 : 1);
        if (numInnerHits == 1) {
            InnerHitBuilder innerHit = InnerHitBuilderTests.randomInnerHits();
            builder.setInnerHits(innerHit);
        } else if (numInnerHits > 1) {
            List<InnerHitBuilder> innerHits = new ArrayList<>(numInnerHits);
            for (int i = 0; i < numInnerHits; i++) {
                innerHits.add(InnerHitBuilderTests.randomInnerHits());
            }

            builder.setInnerHits(innerHits);
        }

        return builder;
    }

    @Override
    protected CollapseBuilder createTestInstance() {
        return randomCollapseBuilder();
    }

    @Override
    protected Writeable.Reader<CollapseBuilder> instanceReader() {
        return CollapseBuilder::new;
    }

    @Override
    protected CollapseBuilder mutateInstance(CollapseBuilder instance) throws IOException {
        CollapseBuilder newBuilder;
        switch (between(0, 2)) {
            case 0:
                newBuilder = new CollapseBuilder(instance.getField() + randomAlphaOfLength(10));
                newBuilder.setMaxConcurrentGroupRequests(instance.getMaxConcurrentGroupRequests());
                newBuilder.setInnerHits(instance.getInnerHits());
                break;
            case 1:
                newBuilder = copyInstance(instance);
                newBuilder.setMaxConcurrentGroupRequests(instance.getMaxConcurrentGroupRequests() + between(1, 20));
                break;
            case 2:
            default:
                newBuilder = copyInstance(instance);
                List<InnerHitBuilder> innerHits = new ArrayList<>(newBuilder.getInnerHits());
                for (int i = 0; i < between(1, 5); i++) {
                    innerHits.add(InnerHitBuilderTests.randomInnerHits());
                }
                newBuilder.setInnerHits(innerHits);
                break;
        }
        return newBuilder;
    }

    @Override
    protected NamedWriteableRegistry getNamedWriteableRegistry() {
        return namedWriteableRegistry;
    }

    @Override
    protected NamedXContentRegistry xContentRegistry() {
        return xContentRegistry;
    }

    public void testBuild() throws IOException {
        Directory dir = new ByteBuffersDirectory();
        try (IndexWriter writer = new IndexWriter(dir, newIndexWriterConfig(new MockAnalyzer(random())))) {
            writer.commit();
        }
        QueryShardContext shardContext = mock(QueryShardContext.class);
        try (IndexReader reader = DirectoryReader.open(dir)) {
            when(shardContext.getIndexReader()).thenReturn(reader);

            MappedFieldType numberFieldType = new NumberFieldMapper.NumberFieldType("field", NumberFieldMapper.NumberType.LONG);
            when(shardContext.fieldMapper("field")).thenReturn(numberFieldType);
            CollapseBuilder builder = new CollapseBuilder("field");
            CollapseContext collapseContext = builder.build(shardContext);
            assertEquals(collapseContext.getFieldType(), numberFieldType);

            numberFieldType = new NumberFieldMapper.NumberFieldType(
                "field",
                NumberFieldMapper.NumberType.LONG,
                true,
                false,
                false,
                false,
                null,
                Collections.emptyMap()
            );
            when(shardContext.fieldMapper("field")).thenReturn(numberFieldType);
            IllegalArgumentException exc = expectThrows(IllegalArgumentException.class, () -> builder.build(shardContext));
            assertEquals(exc.getMessage(), "cannot collapse on field `field` without `doc_values`");

            numberFieldType = new NumberFieldMapper.NumberFieldType(
                "field",
                NumberFieldMapper.NumberType.LONG,
                false,
                false,
                true,
                false,
                null,
                Collections.emptyMap()
            );
            when(shardContext.fieldMapper("field")).thenReturn(numberFieldType);
            builder.setInnerHits(new InnerHitBuilder());
            exc = expectThrows(IllegalArgumentException.class, () -> builder.build(shardContext));
            assertEquals(
                exc.getMessage(),
                "cannot expand `inner_hits` for collapse field `field`, only indexed field can retrieve `inner_hits`"
            );

            MappedFieldType keywordFieldType = new KeywordFieldMapper.KeywordFieldType("field");
            when(shardContext.fieldMapper("field")).thenReturn(keywordFieldType);
            CollapseBuilder kbuilder = new CollapseBuilder("field");
            collapseContext = kbuilder.build(shardContext);
            assertEquals(collapseContext.getFieldType(), keywordFieldType);

            keywordFieldType = new KeywordFieldMapper.KeywordFieldType("field", true, false, Collections.emptyMap());
            when(shardContext.fieldMapper("field")).thenReturn(keywordFieldType);
            exc = expectThrows(IllegalArgumentException.class, () -> kbuilder.build(shardContext));
            assertEquals(exc.getMessage(), "cannot collapse on field `field` without `doc_values`");

            keywordFieldType = new KeywordFieldMapper.KeywordFieldType("field", false, true, Collections.emptyMap());
            when(shardContext.fieldMapper("field")).thenReturn(keywordFieldType);
            kbuilder.setInnerHits(new InnerHitBuilder());
            exc = expectThrows(IllegalArgumentException.class, () -> builder.build(shardContext));
            assertEquals(
                exc.getMessage(),
                "cannot expand `inner_hits` for collapse field `field`, only indexed field can retrieve `inner_hits`"
            );

        }
    }

    public void testBuildWithExceptions() {
        QueryShardContext shardContext = mock(QueryShardContext.class);
        {
            CollapseBuilder builder = new CollapseBuilder("unknown_field");
            IllegalArgumentException exc = expectThrows(IllegalArgumentException.class, () -> builder.build(shardContext));
            assertEquals(exc.getMessage(), "no mapping found for `unknown_field` in order to collapse on");
        }

        {
            MappedFieldType fieldType = new MappedFieldType("field", true, false, true, TextSearchInfo.NONE, Collections.emptyMap()) {
                @Override
                public String typeName() {
                    return null;
                }

                @Override
                public ValueFetcher valueFetcher(QueryShardContext context, SearchLookup searchLookup, String format) {
                    throw new UnsupportedOperationException();
                }

                @Override
                public Query termQuery(Object value, QueryShardContext context) {
                    return null;
                }

                public Query existsQuery(QueryShardContext context) {
                    return null;
                }
            };
            when(shardContext.fieldMapper("field")).thenReturn(fieldType);
            CollapseBuilder builder = new CollapseBuilder("field");
            IllegalArgumentException exc = expectThrows(IllegalArgumentException.class, () -> builder.build(shardContext));
            assertEquals(exc.getMessage(), "unknown type for collapse field `field`, only keywords and numbers are accepted");
        }
    }

    @Override
    protected CollapseBuilder doParseInstance(XContentParser parser) {
        return CollapseBuilder.fromXContent(parser);
    }

    @Override
    protected String[] getShuffleFieldsExceptions() {
        // disable xcontent shuffling on the highlight builder
        return new String[] { "fields" };
    }
}