/*
 * 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.druid.sql.calcite.expression.builtin;

import org.apache.calcite.rex.RexNode;
import org.apache.calcite.sql.SqlFunction;
import org.apache.calcite.sql.SqlFunctionCategory;
import org.apache.calcite.sql.SqlOperator;
import org.apache.calcite.sql.type.SqlTypeFamily;
import org.apache.calcite.sql.type.SqlTypeName;
import org.apache.druid.segment.column.RowSignature;
import org.apache.druid.sql.calcite.expression.DruidExpression;
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 javax.annotation.Nullable;

/**
 * A SQL operator conversion for the {@link org.apache.druid.math.expr.Function.Sleep} expression.
 * The expression is currently evaluated during the query planning when the given argument is a number literal.
 */
public class SleepOperatorConversion implements SqlOperatorConversion
{
  private static final SqlFunction SQL_FUNCTION = OperatorConversions
      .operatorBuilder("SLEEP")
      .operandTypes(SqlTypeFamily.NUMERIC)
      .requiredOperands(1)
      .returnTypeNullable(SqlTypeName.VARCHAR) // always null
      .functionCategory(SqlFunctionCategory.TIMEDATE)
      .build();

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

  @Nullable
  @Override
  public DruidExpression toDruidExpression(PlannerContext plannerContext, RowSignature rowSignature, RexNode rexNode)
  {
    return OperatorConversions.convertCall(plannerContext, rowSignature, rexNode, "sleep");
  }
}