/*
 * 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.util.List;
import org.apache.hadoop.conf.Configuration;
import org.apache.phoenix.expression.Expression;
import org.apache.phoenix.expression.LiteralExpression;
import org.apache.phoenix.expression.aggregator.Aggregator;
import org.apache.phoenix.expression.aggregator.FirstLastValueBaseClientAggregator;
import org.apache.phoenix.expression.aggregator.FirstLastValueServerAggregator;
import org.apache.phoenix.parse.FunctionParseNode;
import org.apache.phoenix.parse.NthValueAggregateParseNode;
import org.apache.phoenix.schema.types.PBoolean;
import org.apache.phoenix.schema.types.PInteger;

/**
 * Built-in function for
 * {@code NTH_VALUE(<expression>, <expression>) WITHIN GROUP (ORDER BY <expression> ASC/DESC) }
 * aggregate function
 */
@FunctionParseNode.BuiltInFunction(name = NthValueFunction.NAME,
    nodeClass = NthValueAggregateParseNode.class,
    args = { @FunctionParseNode.Argument(),
      @FunctionParseNode.Argument(allowedTypes = { PBoolean.class }, isConstant = true),
      @FunctionParseNode.Argument(),
      @FunctionParseNode.Argument(allowedTypes = { PInteger.class }, isConstant = true) })
public class NthValueFunction extends FirstLastValueBaseFunction {

  public static final String NAME = "NTH_VALUE";
  private int offset;

  public NthValueFunction() {
  }

  public NthValueFunction(List<Expression> childExpressions) {
    this(childExpressions, null);
  }

  public NthValueFunction(List<Expression> childExpressions, CountAggregateFunction delegate) {
    super(childExpressions, delegate);
  }

  @Override
  public Aggregator newServerAggregator(Configuration conf) {
    FirstLastValueServerAggregator aggregator = new FirstLastValueServerAggregator();

    offset = ((Number) ((LiteralExpression) children.get(3)).getValue()).intValue();
    boolean order = (Boolean) ((LiteralExpression) children.get(1)).getValue();

    aggregator.init(children, order, offset);

    return aggregator;
  }

  @Override
  public Aggregator newClientAggregator() {
    FirstLastValueBaseClientAggregator aggregator = new FirstLastValueBaseClientAggregator();

    if (children.size() < 3) {
      aggregator.init(offset, false);
    } else {
      aggregator.init(((Number) ((LiteralExpression) children.get(3)).getValue()).intValue(),
        false);
    }

    return aggregator;
  }

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

}
