content: /*
   * 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.calcite.adapter.druid;
  
  import com.fasterxml.jackson.core.JsonGenerator;
  
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  import java.io.IOException;
  
  import static org.apache.calcite.adapter.druid.DruidQuery.writeField;
  import static org.apache.calcite.adapter.druid.DruidQuery.writeFieldIf;
  import static org.apache.calcite.util.DateTimeStringUtils.ISO_DATETIME_FRACTIONAL_SECOND_FORMAT;
  
  import static java.util.Objects.requireNonNull;
  
  /**
   * Implementation of extraction function DimensionSpec.
   *
   * <p>The extraction function implementation returns dimension values transformed
   * using the given extraction function.
   */
  public class ExtractionDimensionSpec implements DimensionSpec {
    private final String dimension;
    private final ExtractionFunction extractionFunction;
    private final String outputName;
    private final DruidType outputType;
  
    public ExtractionDimensionSpec(String dimension, ExtractionFunction extractionFunction,
        String outputName) {
      this(dimension, extractionFunction, outputName, DruidType.STRING);
    }
  
    public ExtractionDimensionSpec(String dimension, ExtractionFunction extractionFunction,
        String outputName, DruidType outputType) {
      this.dimension = requireNonNull(dimension, "dimension");
      this.extractionFunction =
          requireNonNull(extractionFunction, "extractionFunction");
      this.outputName = outputName;
      this.outputType = outputType == null ? DruidType.STRING : outputType;
    }
  
    @Override public String getOutputName() {
      return outputName;
    }
  
    @Override public DruidType getOutputType() {
      return outputType;
    }
  
    @Override public ExtractionFunction getExtractionFn() {
      return extractionFunction;
    }
  
    @Override public String getDimension() {
      return dimension;
    }
  
    @Override public void write(JsonGenerator generator) throws IOException {
      generator.writeStartObject();
      generator.writeStringField("type", "extraction");
      generator.writeStringField("dimension", dimension);
      writeFieldIf(generator, "outputName", outputName);
      writeField(generator, "extractionFn", extractionFunction);
      generator.writeEndObject();
    }
  
    /** Returns a valid {@link Granularity} of floor extract, or null when not
     * possible.
     *
     * @param dimensionSpec Druid Dimension specification
     */
    public static @Nullable Granularity toQueryGranularity(DimensionSpec dimensionSpec) {
      if (!DruidTable.DEFAULT_TIMESTAMP_COLUMN.equals(dimensionSpec.getDimension())) {
        // Only __time column can be substituted by granularity
        return null;
      }
      final ExtractionFunction extractionFunction = dimensionSpec.getExtractionFn();
      if (extractionFunction == null) {
        // No Extract thus no Granularity
        return null;
      }
      if (extractionFunction instanceof TimeExtractionFunction) {
        Granularity granularity = ((TimeExtractionFunction) extractionFunction).getGranularity();
        String format = ((TimeExtractionFunction) extractionFunction).getFormat();
        if (!ISO_DATETIME_FRACTIONAL_SECOND_FORMAT.equals(format)) {
          return null;
        }
        return granularity;
      }
      return null;
    }
  
  }
  