// Path: src/main/java/org/elasticsearch/ml/training/ModelTrainer.java
// interface TrainingSession {
//     AggregationBuilder trainingRequest();
//     String model(SearchResponse response);
// }


import org.elasticsearch.ResourceNotFoundException;
import org.elasticsearch.action.ActionListener;
import org.elasticsearch.action.search.SearchRequestBuilder;
import org.elasticsearch.action.search.SearchResponse;
import org.elasticsearch.client.Client;
import org.elasticsearch.cluster.metadata.AliasOrIndex;
import org.elasticsearch.cluster.metadata.IndexMetaData;
import org.elasticsearch.cluster.metadata.MappingMetaData;
import org.elasticsearch.cluster.metadata.MetaData;
import org.elasticsearch.cluster.service.ClusterService;
import org.elasticsearch.common.ParseFieldMatcher;
import org.elasticsearch.common.component.AbstractComponent;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.common.xcontent.XContentFactory;
import org.elasticsearch.common.xcontent.XContentParser;
import org.elasticsearch.common.xcontent.XContentType;
import org.elasticsearch.index.IndexNotFoundException;
import org.elasticsearch.index.query.QueryBuilder;
import org.elasticsearch.index.query.QueryParseContext;
import org.elasticsearch.ml.training.ModelTrainer.TrainingSession;
import org.elasticsearch.search.SearchRequestParsers;
import java.io.IOException;
import java.util.List;
import java.util.Map;
import java.util.Optional;

    public TrainingService(Settings settings, ClusterService clusterService, Client client, ModelTrainers modelTrainers,
                           SearchRequestParsers searchRequestParsers) {
        super(settings);
        this.clusterService = clusterService;
        this.modelTrainers = modelTrainers;
        this.client = client;
        this.searchRequestParsers = searchRequestParsers;
        this.parseFieldMatcher = new ParseFieldMatcher(settings);
    }

    public void train(String modelType, Settings modelSettings, String index, String type, Map<String, Object> query,
                      List<ModelInputField> fields, ModelTargetField outputField, ActionListener<String> listener) {
        try {
            MetaData metaData = clusterService.state().getMetaData();
            AliasOrIndex aliasOrIndex = metaData.getAliasAndIndexLookup().get(index);
            if (aliasOrIndex == null) {
                throw new IndexNotFoundException("the training index [" + index + "] not found");
            }
            if (aliasOrIndex.getIndices().size() != 1) {
                throw new IllegalArgumentException("can only train on a single index");
            }
            IndexMetaData indexMetaData = aliasOrIndex.getIndices().get(0);
            MappingMetaData mappingMetaData = indexMetaData.mapping(type);
            if (mappingMetaData == null) {
                throw new ResourceNotFoundException("the training type [" + type + "] not found");
            }

            Optional<QueryBuilder> queryBuilder = query.isEmpty() ? Optional.empty() : parseQuery(query);

// Path: src/main/java/org/elasticsearch/ml/training/ModelTrainer.java
// interface TrainingSession {
//     AggregationBuilder trainingRequest();
//     String model(SearchResponse response);
// }


// Path: src/main/java/org/elasticsearch/ml/training/TrainingService.java
import org.elasticsearch.ResourceNotFoundException;
import org.elasticsearch.action.ActionListener;
import org.elasticsearch.action.search.SearchRequestBuilder;
import org.elasticsearch.action.search.SearchResponse;
import org.elasticsearch.client.Client;
import org.elasticsearch.cluster.metadata.AliasOrIndex;
import org.elasticsearch.cluster.metadata.IndexMetaData;
import org.elasticsearch.cluster.metadata.MappingMetaData;
import org.elasticsearch.cluster.metadata.MetaData;
import org.elasticsearch.cluster.service.ClusterService;
import org.elasticsearch.common.ParseFieldMatcher;
import org.elasticsearch.common.component.AbstractComponent;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.common.xcontent.XContentFactory;
import org.elasticsearch.common.xcontent.XContentParser;
import org.elasticsearch.common.xcontent.XContentType;
import org.elasticsearch.index.IndexNotFoundException;
import org.elasticsearch.index.query.QueryBuilder;
import org.elasticsearch.index.query.QueryParseContext;
import org.elasticsearch.ml.training.ModelTrainer.TrainingSession;
import org.elasticsearch.search.SearchRequestParsers;
import java.io.IOException;
import java.util.List;
import java.util.Map;
import java.util.Optional;


    public TrainingService(Settings settings, ClusterService clusterService, Client client, ModelTrainers modelTrainers,
                           SearchRequestParsers searchRequestParsers) {
        super(settings);
        this.clusterService = clusterService;
        this.modelTrainers = modelTrainers;
        this.client = client;
        this.searchRequestParsers = searchRequestParsers;
        this.parseFieldMatcher = new ParseFieldMatcher(settings);
    }

    public void train(String modelType, Settings modelSettings, String index, String type, Map<String, Object> query,
                      List<ModelInputField> fields, ModelTargetField outputField, ActionListener<String> listener) {
        try {
            MetaData metaData = clusterService.state().getMetaData();
            AliasOrIndex aliasOrIndex = metaData.getAliasAndIndexLookup().get(index);
            if (aliasOrIndex == null) {
                throw new IndexNotFoundException("the training index [" + index + "] not found");
            }
            if (aliasOrIndex.getIndices().size() != 1) {
                throw new IllegalArgumentException("can only train on a single index");
            }
            IndexMetaData indexMetaData = aliasOrIndex.getIndices().get(0);
            MappingMetaData mappingMetaData = indexMetaData.mapping(type);
            if (mappingMetaData == null) {
                throw new ResourceNotFoundException("the training type [" + type + "] not found");
            }

            Optional<QueryBuilder> queryBuilder = query.isEmpty() ? Optional.empty() : parseQuery(query);

            TrainingSession trainingSession =