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 org.apache.calcite.avatica.util.TimeUnitRange;
  
  import com.fasterxml.jackson.core.JsonGenerator;
  
  import java.io.IOException;
  
  import static org.apache.calcite.adapter.druid.DruidQuery.writeFieldIf;
  
  import static java.util.Objects.requireNonNull;
  
  /**
   * Factory methods and helpers for {@link Granularity}.
   */
  public class Granularities {
    // Private constructor for utility class
    private Granularities() {}
  
    /** Returns a Granularity that causes all rows to be rolled up into one. */
    public static Granularity all() {
      return AllGranularity.INSTANCE;
    }
  
    /** Creates a Granularity based on a time unit.
     *
     * <p>When used in a query, Druid will rollup and round time values based on
     * specified period and timezone. */
    public static Granularity createGranularity(TimeUnitRange timeUnit,
        String timeZone) {
      switch (timeUnit) {
      case YEAR:
        return new PeriodGranularity(Granularity.Type.YEAR, "P1Y", timeZone);
      case QUARTER:
        return new PeriodGranularity(Granularity.Type.QUARTER, "P3M", timeZone);
      case MONTH:
        return new PeriodGranularity(Granularity.Type.MONTH, "P1M", timeZone);
      case WEEK:
        return new PeriodGranularity(Granularity.Type.WEEK, "P1W", timeZone);
      case DAY:
        return new PeriodGranularity(Granularity.Type.DAY, "P1D", timeZone);
      case HOUR:
        return new PeriodGranularity(Granularity.Type.HOUR, "PT1H", timeZone);
      case MINUTE:
        return new PeriodGranularity(Granularity.Type.MINUTE, "PT1M", timeZone);
      case SECOND:
        return new PeriodGranularity(Granularity.Type.SECOND, "PT1S", timeZone);
      default:
        throw new AssertionError(timeUnit);
      }
    }
  
    /** Implementation of {@link Granularity} for {@link Granularity.Type#ALL}.
     * A singleton. */
    private enum AllGranularity implements Granularity {
      INSTANCE;
  
      @Override public void write(JsonGenerator generator) throws IOException {
        generator.writeObject("all");
      }
  
      @Override public Type getType() {
        return Type.ALL;
      }
    }
  
    /** Implementation of {@link Granularity} based on a time unit.
     * Corresponds to PeriodGranularity in Druid. */
    private static class PeriodGranularity implements Granularity {
      private final Type type;
      private final String period;
      private final String timeZone;
  
      private PeriodGranularity(Type type, String period, String timeZone) {
        this.type = requireNonNull(type, "type");
        this.period = requireNonNull(period, "period");
        this.timeZone = requireNonNull(timeZone, "timeZone");
      }
  
      @Override public void write(JsonGenerator generator) throws IOException {
        generator.writeStartObject();
        generator.writeStringField("type", "period");
        writeFieldIf(generator, "period", period);
        writeFieldIf(generator, "timeZone", timeZone);
        generator.writeEndObject();
      }
  
      @Override public Type getType() {
        return type;
      }
    }
  }
  