/*
 * Copyright 2021-present the original author or authors.
 *
 * Licensed 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
 *
 *      https://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.
 */
package org.springframework.data.elasticsearch.client.elc;

import co.elastic.clients.elasticsearch.core.GetResponse;
import co.elastic.clients.elasticsearch.core.MgetResponse;
import co.elastic.clients.elasticsearch.core.explain.ExplanationDetail;
import co.elastic.clients.elasticsearch.core.get.GetResult;
import co.elastic.clients.elasticsearch.core.search.CompletionSuggestOption;
import co.elastic.clients.elasticsearch.core.search.Hit;
import co.elastic.clients.elasticsearch.core.search.NestedIdentity;
import co.elastic.clients.json.JsonData;
import co.elastic.clients.json.JsonpMapper;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.jspecify.annotations.Nullable;
import org.springframework.data.elasticsearch.core.MultiGetItem;
import org.springframework.data.elasticsearch.core.document.Document;
import org.springframework.data.elasticsearch.core.document.Explanation;
import org.springframework.data.elasticsearch.core.document.NestedMetaData;
import org.springframework.data.elasticsearch.core.document.SearchDocument;
import org.springframework.data.elasticsearch.core.document.SearchDocumentAdapter;
import org.springframework.data.elasticsearch.core.document.SearchDocumentResponse;
import org.springframework.util.Assert;

import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.function.Function;
import java.util.stream.Collectors;

/**
 * Utility class to adapt different Elasticsearch responses to a
 * {@link org.springframework.data.elasticsearch.core.document.Document}
 *
 * @author Peter-Josef Meisch
 * @author Haibo Liu
 * @author Mohamed El Harrougui
 * @since 4.4
 */
final class DocumentAdapters {

    private static final Log LOGGER = LogFactory.getLog(DocumentAdapters.class);

    private DocumentAdapters() {
    }

    /**
     * Creates a {@link SearchDocument} from a {@link Hit} returned by the Elasticsearch client.
     *
     * @param hit         the hit object
     * @param jsonpMapper to map JsonData objects
     * @return the created {@link SearchDocument}
     */
    public static SearchDocument from(Hit<?> hit, JsonpMapper jsonpMapper) {

        Assert.notNull(hit, "hit must not be null");

        Map<String, List<String>> highlightFields = hit.highlight();

        Map<String, SearchDocumentResponse> innerHits = new LinkedHashMap<>();
        hit.innerHits().forEach((name, innerHitsResult) -> {
            // noinspection ReturnOfNull
            innerHits.put(name, SearchDocumentResponseBuilder.from(innerHitsResult.hits(), null, null, null, 0, null, null,
                    searchDocument -> null, jsonpMapper));
        });

        NestedMetaData nestedMetaData = from(hit.nested());

        Explanation explanation = from(hit.explanation());

        Map<String, Double> matchedQueries = hit.matchedQueries();

        Function<Map<String, JsonData>, EntityAsMap> fromFields = fields -> {
            StringBuilder sb = new StringBuilder("{");
            final boolean[] firstField = {true};
            hit.fields().forEach((key, jsonData) -> {
                if (!firstField[0]) {
                    sb.append(',');
                }
                sb.append('"').append(key).append("\":") //
                        .append(jsonData.toJson(jsonpMapper).toString());
                firstField[0] = false;
            });
            sb.append('}');
            return new EntityAsMap().fromJson(sb.toString());
        };

        EntityAsMap hitFieldsAsMap = fromFields.apply(hit.fields());

        Map<String, List<Object>> documentFields = new LinkedHashMap<>();
        hitFieldsAsMap.forEach((key, value) -> {
            if (value instanceof List) {
                // noinspection unchecked
                documentFields.put(key, (List<Object>) value);
            } else {
                documentFields.put(key, Collections.singletonList(value));
            }
        });

        Document document;
        Object source = hit.source();
        if (source == null) {
            document = Document.from(hitFieldsAsMap);
        } else {
            if (source instanceof EntityAsMap entityAsMap) {
                document = Document.from(entityAsMap);
            } else if (source instanceof JsonData jsonData) {
                document = Document.from(jsonData.to(EntityAsMap.class));
            } else {

                if (LOGGER.isWarnEnabled()) {
                    LOGGER.warn(String.format("Cannot map from type " + source.getClass().getName()));
                }
                document = Document.create();
            }
        }
        document.setIndex(hit.index());
        document.setId(hit.id());

        if (hit.version() != null) {
            document.setVersion(hit.version());
        }
        document.setSeqNo(hit.seqNo() != null && hit.seqNo() >= 0 ? hit.seqNo() : -2); // -2 was the default value in the
        // old client
        document.setPrimaryTerm(hit.primaryTerm() != null && hit.primaryTerm() > 0 ? hit.primaryTerm() : 0);

        float score = hit.score() != null ? hit.score().floatValue() : Float.NaN;
        return new SearchDocumentAdapter(document, score, hit.sort().stream().map(TypeUtils::toObject).toArray(),
                documentFields, highlightFields, innerHits, nestedMetaData, explanation, matchedQueries, hit.routing());
    }

    public static SearchDocument from(CompletionSuggestOption<EntityAsMap> completionSuggestOption) {

        Document document = completionSuggestOption.source() != null ? Document.from(completionSuggestOption.source())
                : Document.create();
        document.setIndex(completionSuggestOption.index());

        if (completionSuggestOption.id() != null) {
            document.setId(completionSuggestOption.id());
        }

        float score = completionSuggestOption.score() != null ? completionSuggestOption.score().floatValue() : Float.NaN;
        return new SearchDocumentAdapter(document, score, new Object[]{}, Collections.emptyMap(), Collections.emptyMap(),
                Collections.emptyMap(), null, null, null, completionSuggestOption.routing());
    }

    @Nullable
    private static Explanation from(co.elastic.clients.elasticsearch.core.explain.@Nullable Explanation explanation) {

        if (explanation == null) {
            return null;
        }
        List<Explanation> details = explanation.details().stream().map(DocumentAdapters::from).collect(Collectors.toList());
        return new Explanation(true, (double) explanation.value(), explanation.description(), details);
    }

    private static Explanation from(ExplanationDetail explanationDetail) {

        List<Explanation> details = explanationDetail.details().stream().map(DocumentAdapters::from)
                .collect(Collectors.toList());
        return new Explanation(null, (double) explanationDetail.value(), explanationDetail.description(), details);
    }

    @Nullable
    private static NestedMetaData from(@Nullable NestedIdentity nestedIdentity) {

        if (nestedIdentity == null) {
            return null;
        }

        NestedMetaData child = from(nestedIdentity.nested());
        return NestedMetaData.of(nestedIdentity.field(), nestedIdentity.offset(), child);
    }

    /**
     * Creates a {@link Document} from a {@link GetResponse} where the found document is contained as {@link EntityAsMap}.
     *
     * @param getResponse the response instance
     * @return the Document
     */
    @Nullable
    public static Document from(GetResult<EntityAsMap> getResponse) {

        Assert.notNull(getResponse, "getResponse must not be null");

        if (!getResponse.found()) {
            return null;
        }

        Document document = getResponse.source() != null ? Document.from(getResponse.source()) : Document.create();
        document.setIndex(getResponse.index());
        document.setId(getResponse.id());

        if (getResponse.version() != null) {
            document.setVersion(getResponse.version());
        }

        if (getResponse.seqNo() != null) {
            document.setSeqNo(getResponse.seqNo());
        }

        if (getResponse.primaryTerm() != null) {
            document.setPrimaryTerm(getResponse.primaryTerm());
        }

        return document;
    }

    /**
     * Creates a list of {@link MultiGetItem}s from a {@link MgetResponse} where the data is contained as
     * {@link EntityAsMap} instances.
     *
     * @param mgetResponse the response instance
     * @return list of multiget items
     */
    public static List<MultiGetItem<Document>> from(MgetResponse<EntityAsMap> mgetResponse) {

        Assert.notNull(mgetResponse, "mgetResponse must not be null");

        return mgetResponse.docs().stream() //
                .map(itemResponse -> MultiGetItem.of( //
                        itemResponse.isFailure() ? null : from(itemResponse.result()), //
                        ResponseConverter.getFailure(itemResponse)))
                .collect(Collectors.toList());
    }
}
