/*
 * Copyright OpenSearch Contributors
 * SPDX-License-Identifier: Apache-2.0
 */

package org.opensearch.knn.index.mapper;

import org.apache.lucene.document.FieldType;
import org.opensearch.common.Explicit;
import org.opensearch.common.Strings;
import org.opensearch.common.xcontent.XContentFactory;
import org.opensearch.knn.index.KNNMethodContext;
import org.opensearch.knn.index.util.KNNEngine;

import java.io.IOException;

import static org.opensearch.knn.common.KNNConstants.DIMENSION;
import static org.opensearch.knn.common.KNNConstants.KNN_ENGINE;
import static org.opensearch.knn.common.KNNConstants.PARAMETERS;
import static org.opensearch.knn.common.KNNConstants.SPACE_TYPE;

/**
 * Field mapper for method definition in mapping
 */
public class MethodFieldMapper extends KNNVectorFieldMapper {

    MethodFieldMapper(
        String simpleName,
        KNNVectorFieldType mappedFieldType,
        MultiFields multiFields,
        CopyTo copyTo,
        Explicit<Boolean> ignoreMalformed,
        boolean stored,
        boolean hasDocValues,
        KNNMethodContext knnMethodContext
    ) {

        super(simpleName, mappedFieldType, multiFields, copyTo, ignoreMalformed, stored, hasDocValues);

        this.knnMethod = knnMethodContext;

        this.fieldType = new FieldType(KNNVectorFieldMapper.Defaults.FIELD_TYPE);

        this.fieldType.putAttribute(DIMENSION, String.valueOf(dimension));
        this.fieldType.putAttribute(SPACE_TYPE, knnMethodContext.getSpaceType().getValue());

        KNNEngine knnEngine = knnMethodContext.getKnnEngine();
        this.fieldType.putAttribute(KNN_ENGINE, knnEngine.getName());

        try {
            this.fieldType.putAttribute(
                PARAMETERS,
                Strings.toString(XContentFactory.jsonBuilder().map(knnEngine.getMethodAsMap(knnMethodContext)))
            );
        } catch (IOException ioe) {
            throw new RuntimeException(String.format("Unable to create KNNVectorFieldMapper: %s", ioe));
        }

        this.fieldType.freeze();
    }
}