/*
 * JBoss, Home of Professional Open Source.
 * See the COPYRIGHT.txt file distributed with this work for information
 * regarding copyright ownership.  Some portions may be licensed
 * to Red Hat, Inc. under one or more contributor license agreements.
 * 
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301 USA.
 */

package org.teiid.query.function.aggregate;

import java.util.List;

import org.teiid.api.exception.query.ExpressionEvaluationException;
import org.teiid.api.exception.query.FunctionExecutionException;
import org.teiid.core.TeiidComponentException;
import org.teiid.query.sql.symbol.AggregateSymbol.Type;
import org.teiid.query.util.CommandContext;

/**
 * computes rank/dense_rank
 */
public class RankingFunction extends AggregateFunction {
	
	private int count = 0;
	private int lastCount = 0;
	private Type type;
	
	public RankingFunction(Type function) {
		this.type = function;
	}

	@Override
	public void reset() {
		count = 0;
		lastCount = 0;
	}
	
	@Override
	public void addInputDirect(List<?> tuple, CommandContext commandContext)
			throws FunctionExecutionException, ExpressionEvaluationException,
			TeiidComponentException {
		if (type == Type.RANK) {
			count++;
		}
	}
	
	@Override
	public Object getResult(CommandContext commandContext) throws FunctionExecutionException,
			ExpressionEvaluationException, TeiidComponentException {
		if (type == Type.DENSE_RANK) {
			count++;
			return count;
		}
		int result = ++lastCount;
		lastCount = count;
		return result;
	}

}
