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/*
 * Licensed to Elasticsearch B.V. under one or more contributor
 * license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright
 * ownership. Elasticsearch B.V. 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 co.elastic.clients.elasticsearch._helpers.esql.objects;

import co.elastic.clients.ApiClient;
import co.elastic.clients.elasticsearch._helpers.esql.EsqlAdapter;
import co.elastic.clients.elasticsearch._helpers.esql.EsqlAdapterBase;
import co.elastic.clients.elasticsearch._helpers.esql.EsqlMetadata;
import co.elastic.clients.elasticsearch.esql.QueryRequest;
import co.elastic.clients.json.BufferingJsonGenerator;
import co.elastic.clients.json.BufferingJsonpMapper;
import co.elastic.clients.json.JsonpMapper;
import co.elastic.clients.json.JsonpUtils;
import co.elastic.clients.transport.ElasticsearchTransport;
import co.elastic.clients.transport.endpoints.BinaryResponse;
import jakarta.json.stream.JsonParser;

import java.io.IOException;
import java.lang.reflect.Type;
import java.util.ArrayList;
import java.util.List;

/**
 * And ES|QL adapter that returns an iterable of domain objects
 */
public class ObjectsEsqlAdapter implements EsqlAdapter> {

    public static  ObjectsEsqlAdapter of(Class clazz) {
        return new ObjectsEsqlAdapter<>(clazz);
    }

    public static  ObjectsEsqlAdapter of(Type type) {
        return new ObjectsEsqlAdapter<>(type);
    }

    private final Type type;

    public ObjectsEsqlAdapter(Type type) {
        this.type = type;
    }

    @Override
    public String format() {
        return "json";
    }

    @Override
    public boolean columnar() {
        return false;
    }

    @Override
    public Iterable deserialize(ApiClient client, QueryRequest request, BinaryResponse response)
        throws IOException {
        JsonpMapper mapper = client._jsonpMapper();

        if (!(mapper instanceof BufferingJsonpMapper)) {
            throw new IllegalArgumentException("ES|QL object mapping currently only works with JacksonJsonpMapper");
        }

        JsonParser parser = mapper.jsonProvider().createParser(response.content());

        List columns = EsqlAdapterBase.readHeader(parser, mapper).columns;

        List results = new ArrayList<>();
        JsonParser.Event event;

        while ((event = parser.next()) != JsonParser.Event.END_ARRAY) {
            // Start of row
            JsonpUtils.expectEvent(parser, JsonParser.Event.START_ARRAY, event);

            results.add(parseRow(columns, parser, mapper));

            // End of row
            JsonpUtils.expectNextEvent(parser, JsonParser.Event.END_ARRAY);
        }

        EsqlAdapterBase.readFooter(parser);

        return results;
    }

    private T parseRow(List columns, JsonParser parser, JsonpMapper mapper) {
        // FIXME: add a second implementation not requiring a buffering parser
        BufferingJsonGenerator buffer = ((BufferingJsonpMapper) mapper).createBufferingGenerator();

        buffer.writeStartObject();
        for (EsqlMetadata.EsqlColumn column : columns) {
            buffer.writeKey(column.name());
            JsonpUtils.copy(parser, buffer);
        }
        buffer.writeEnd();

        return mapper.deserialize(buffer.getParser(), type);
    }
}