/*
 * 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.beam.sdk.extensions.sql.impl.interpreter.operator.date;

import java.util.List;
import org.apache.beam.sdk.extensions.sql.impl.interpreter.BeamSqlExpressionEnvironment;
import org.apache.beam.sdk.extensions.sql.impl.interpreter.operator.BeamSqlExpression;
import org.apache.beam.sdk.extensions.sql.impl.interpreter.operator.BeamSqlPrimitive;
import org.apache.beam.sdk.transforms.windowing.BoundedWindow;
import org.apache.beam.sdk.values.Row;
import org.apache.calcite.sql.type.SqlTypeName;
import org.joda.time.DateTime;

/**
 * {@code BeamSqlExpression} for LOCALTIMESTAMP and CURRENT_TIMESTAMP.
 *
 * <p>Returns the current date and time in the session time zone in a value of datatype TIMESTAMP,
 * with precision digits of precision.
 *
 * <p>NOTE: for simplicity, we will ignore the {@code precision} param.
 */
public class BeamSqlCurrentTimestampExpression extends BeamSqlExpression {
  public BeamSqlCurrentTimestampExpression(List<BeamSqlExpression> operands) {
    super(operands, SqlTypeName.TIMESTAMP);
  }

  @Override
  public boolean accept() {
    int opCount = getOperands().size();
    return opCount <= 1;
  }

  @Override
  public BeamSqlPrimitive evaluate(
      Row inputRow, BoundedWindow window, BeamSqlExpressionEnvironment env) {
    return BeamSqlPrimitive.of(outputType, DateTime.now());
  }
}
