/*
 * 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.phoenix.expression.function;

import java.sql.SQLException;
import java.util.List;
import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import org.apache.phoenix.expression.Expression;
import org.apache.phoenix.parse.FunctionParseNode.BuiltInFunction;
import org.apache.phoenix.schema.tuple.Tuple;
import org.apache.phoenix.schema.types.PDataType;
import org.apache.phoenix.schema.types.PDouble;

/**
 * Function used to represent PI() The function returns a
 * {@link org.apache.phoenix.schema.types.PDouble}
 */
@BuiltInFunction(name = MathPIFunction.NAME, args = {})
public class MathPIFunction extends ScalarFunction {

  public static final String NAME = "PI";

  public MathPIFunction() {
  }

  public MathPIFunction(List<Expression> children) throws SQLException {
    super(children);
  }

  @Override
  public String getName() {
    return NAME;
  }

  @Override
  public boolean evaluate(Tuple tuple, ImmutableBytesWritable ptr) {
    ptr.set(new byte[getDataType().getByteSize()]);
    getDataType().getCodec().encodeDouble(Math.PI, ptr);
    return true;
  }

  @Override
  public PDataType getDataType() {
    return PDouble.INSTANCE;
  }
}
