/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF 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.
 */
package org.apache.camel.component.pgvector.transform;

import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;

import org.apache.camel.Message;
import org.apache.camel.spi.DataType;
import org.apache.camel.spi.DataTypeTransformer;
import org.apache.camel.spi.Transformer;

/**
 * Maps a List of PgVector similarity search results to a List of String for LangChain4j RAG.
 */
@DataTypeTransformer(name = "pgvector:rag",
                     description = "Prepares the PgVector similarity search results to become a List of String for LangChain4j RAG")
public class PgVectorReverseEmbeddingsDataTypeTransformer extends Transformer {

    @Override
    @SuppressWarnings("unchecked")
    public void transform(Message message, DataType from, DataType to) throws Exception {
        List<Map<String, Object>> results = message.getBody(List.class);
        if (results == null) {
            throw new IllegalArgumentException(
                    "Message body must contain similarity search results (List<Map<String, Object>>)");
        }

        List<String> textContents = results.stream()
                .map(row -> (String) row.getOrDefault("text_content", ""))
                .collect(Collectors.toList());

        message.setBody(textContents);
    }
}
