sql/src/main/java/org/apache/druid/sql/calcite/expression/builtin/TimeExtractOperatorConversion.java

/*
 * 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
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package org.apache.druid.sql.calcite.expression.builtin;

import com.google.common.collect.ImmutableList;
import org.apache.calcite.rex.RexCall;
import org.apache.calcite.rex.RexLiteral;
import org.apache.calcite.rex.RexNode;
import org.apache.calcite.sql.SqlFunction;
import org.apache.calcite.sql.SqlFunctionCategory;
import org.apache.calcite.sql.type.SqlTypeFamily;
import org.apache.calcite.sql.type.SqlTypeName;
import org.apache.druid.java.util.common.DateTimes;
import org.apache.druid.java.util.common.StringUtils;
import org.apache.druid.query.expression.TimestampExtractExprMacro;
import org.apache.druid.segment.column.RowSignature;
import org.apache.druid.sql.calcite.expression.DruidExpression;
import org.apache.druid.sql.calcite.expression.Expressions;
import org.apache.druid.sql.calcite.expression.OperatorConversions;
import org.apache.druid.sql.calcite.expression.SqlOperatorConversion;
import org.apache.druid.sql.calcite.planner.PlannerContext;
import org.joda.time.DateTimeZone;

public class TimeExtractOperatorConversion implements SqlOperatorConversion
{
  private static final SqlFunction SQL_FUNCTION = OperatorConversions
      .operatorBuilder("TIME_EXTRACT")
      .operandTypes(SqlTypeFamily.TIMESTAMP, SqlTypeFamily.CHARACTER, SqlTypeFamily.CHARACTER)
      .requiredOperands(2)
      .returnTypeCascadeNullable(SqlTypeName.BIGINT)
      .functionCategory(SqlFunctionCategory.TIMEDATE)
      .build();

  public static DruidExpression applyTimeExtract(
      final DruidExpression timeExpression,
      final TimestampExtractExprMacro.Unit unit,
      final DateTimeZone timeZone
  )
  {
    return DruidExpression.fromFunctionCall(
        "timestamp_extract",
        ImmutableList.of(
            timeExpression,
            DruidExpression.fromExpression(DruidExpression.stringLiteral(unit.name())),
            DruidExpression.fromExpression(DruidExpression.stringLiteral(timeZone.getID()))
        )
    );
  }

  @Override
  public SqlFunction calciteOperator()
  {
    return SQL_FUNCTION;
  }

  @Override
  public DruidExpression toDruidExpression(
      final PlannerContext plannerContext,
      final RowSignature rowSignature,
      final RexNode rexNode
  )
  {
    final RexCall call = (RexCall) rexNode;
    final RexNode timeArg = call.getOperands().get(0);
    final DruidExpression timeExpression = Expressions.toDruidExpression(plannerContext, rowSignature, timeArg);
    if (timeExpression == null) {
      return null;
    }

    final TimestampExtractExprMacro.Unit unit = TimestampExtractExprMacro.Unit.valueOf(
        StringUtils.toUpperCase(RexLiteral.stringValue(call.getOperands().get(1)))
    );

    final DateTimeZone timeZone = OperatorConversions.getOperandWithDefault(
        call.getOperands(),
        2,
        operand -> DateTimes.inferTzFromString(RexLiteral.stringValue(operand)),
        plannerContext.getTimeZone()
    );

    return applyTimeExtract(timeExpression, unit, timeZone);
  }
}