content: /*
   * Copyright © 2018-2025 Commonwealth Scientific and Industrial Research
   * Organisation (CSIRO) ABN 41 687 119 230.
   *
   * 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
   *
   *     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 au.csiro.pathling;
  
  import au.csiro.pathling.encoders.FhirEncoders;
  import jakarta.annotation.Nonnull;
  import org.apache.spark.sql.Dataset;
  import org.apache.spark.sql.Row;
  import org.apache.spark.sql.SparkSession;
  import org.apache.spark.sql.catalyst.encoders.ExpressionEncoder;
  import org.hl7.fhir.instance.model.api.IBaseResource;
  import org.hl7.fhir.r4.model.Enumerations.ResourceType;
  
  /**
   * Common functionality for executing queries using Spark.
   *
   * @author John Grimes
   */
  public abstract class QueryHelpers {
  
    private QueryHelpers() {
    }
  
    /**
     * Creates an empty dataset with the schema of the supplied resource type.
     *
     * @param spark a {@link SparkSession}
     * @param fhirEncoders a {@link FhirEncoders} object
     * @param resourceType the {@link ResourceType} that will determine the shape of the empty
     * dataset
     * @return a new {@link Dataset}
     */
    @Nonnull
    public static Dataset<Row> createEmptyDataset(@Nonnull final SparkSession spark,
        @Nonnull final FhirEncoders fhirEncoders, @Nonnull final ResourceType resourceType) {
      final ExpressionEncoder<IBaseResource> encoder = fhirEncoders.of(resourceType.toCode());
      return spark.emptyDataset(encoder).toDF();
    }
  }
  