/*
 * Copyright 2009-2010 by The Regents of the University of California
 * Licensed 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 from
 * 
 *     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 edu.uci.ics.hyracks.algebricks.core.algebra.expressions;

import java.util.List;

import org.apache.commons.lang3.mutable.Mutable;

import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
import edu.uci.ics.hyracks.algebricks.core.algebra.functions.IFunctionInfo;
import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalExpressionVisitor;

/**
 * 
 * An aggregate function may be executed in a "two step" mode. First the
 * "step-one" aggregates are run and then the results are passed to the
 * "step-two" aggregators. The convention is the following:
 * 
 * 1. The step-one aggregate must be able to accept the same arguments as the
 * original aggregate function call.
 * 
 * 2. The step-two aggregate must be a unary function that accepts as input the
 * output of the step-one aggregate.
 * 
 */

public class AggregateFunctionCallExpression extends AbstractFunctionCallExpression {

    private boolean twoStep;
    private IFunctionInfo stepOneAggregate;
    private IFunctionInfo stepTwoAggregate;

    public AggregateFunctionCallExpression(IFunctionInfo finfo, boolean isTwoStep) {
        super(FunctionKind.AGGREGATE, finfo);
        this.twoStep = isTwoStep;
    }

    public AggregateFunctionCallExpression(IFunctionInfo finfo, boolean isTwoStep,
            List<Mutable<ILogicalExpression>> arguments) {
        super(FunctionKind.AGGREGATE, finfo, arguments);
        this.twoStep = isTwoStep;
    }

    public AggregateFunctionCallExpression(IFunctionInfo finfo, boolean isTwoStep,
            Mutable<ILogicalExpression>... expressions) {
        super(FunctionKind.AGGREGATE, finfo, expressions);
        this.twoStep = isTwoStep;
    }

    public boolean isTwoStep() {
        return twoStep;
    }

    public void setTwoStep(boolean twoStep) {
        this.twoStep = twoStep;
    }

    @Override
    public AggregateFunctionCallExpression cloneExpression() {
        cloneAnnotations();
        List<Mutable<ILogicalExpression>> clonedArgs = cloneArguments();
        AggregateFunctionCallExpression fun = new AggregateFunctionCallExpression(finfo, twoStep, clonedArgs);
        fun.setStepTwoAggregate(stepTwoAggregate);
        fun.setStepOneAggregate(stepOneAggregate);
        return fun;
    }

    public void setStepOneAggregate(IFunctionInfo stepOneAggregate) {
        this.stepOneAggregate = stepOneAggregate;
    }

    public IFunctionInfo getStepOneAggregate() {
        return stepOneAggregate;
    }

    public void setStepTwoAggregate(IFunctionInfo stepTwoAggregate) {
        this.stepTwoAggregate = stepTwoAggregate;
    }

    public IFunctionInfo getStepTwoAggregate() {
        return stepTwoAggregate;
    }

    @Override
    public <R, T> R accept(ILogicalExpressionVisitor<R, T> visitor, T arg) throws AlgebricksException {
        return visitor.visitAggregateFunctionCallExpression(this, arg);
    }

}