/*
 *  RapidMiner
 *
 *  Copyright (C) 2001-2011 by Rapid-I and the contributors
 *
 *  Complete list of developers available at our web site:
 *
 *       http://rapid-i.com
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU Affero General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This program 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 Affero General Public License for more details.
 *
 *  You should have received a copy of the GNU Affero General Public License
 *  along with this program.  If not, see http://www.gnu.org/licenses/.
 */
package com.rapidminer.operator.learner.tree.criterions;

import static com.rapidminer.operator.learner.tree.AbstractTreeLearner.CRITERIA_CLASSES;
import static com.rapidminer.operator.learner.tree.AbstractTreeLearner.CRITERIA_NAMES;
import static com.rapidminer.operator.learner.tree.AbstractTreeLearner.PARAMETER_CRITERION;

import com.rapidminer.example.Attribute;
import com.rapidminer.example.Example;
import com.rapidminer.example.ExampleSet;
import com.rapidminer.operator.OperatorException;
import com.rapidminer.operator.learner.tree.FrequencyCalculator;
import com.rapidminer.operator.learner.tree.MinimalGainHandler;
import com.rapidminer.parameter.ParameterHandler;
import com.rapidminer.tools.Tools;
/**
 * This criterion class can be used for the incremental calculation of benefits.
 * 
 * @author Sebastian Land
 */
public abstract class AbstractCriterion implements Criterion {
	

    // data for incremental calculation
    
    protected double leftWeight;
    protected double rightWeight;
    protected double totalWeight;
    protected double[] totalLabelWeights;
    protected double[] leftLabelWeights;
    protected double[] rightLabelWeights;
    protected Attribute labelAttribute;
    protected Attribute weightAttribute;

	public boolean supportsIncrementalCalculation() {
    	return false;
    }

	public void startIncrementalCalculation(ExampleSet exampleSet) {
		FrequencyCalculator calculator = new FrequencyCalculator();
		rightLabelWeights = calculator.getLabelWeights(exampleSet);
		leftLabelWeights = new double[rightLabelWeights.length];
		totalLabelWeights = new double[rightLabelWeights.length];
		System.arraycopy(rightLabelWeights, 0, totalLabelWeights, 0, rightLabelWeights.length);
		leftWeight = 0;
		rightWeight = calculator.getTotalWeight(totalLabelWeights);
		totalWeight = rightWeight;
		
		labelAttribute = exampleSet.getAttributes().getLabel();
		weightAttribute = exampleSet.getAttributes().getWeight();
	}

	public void swapExample(Example example) {
		double weight = 1;
		if (weightAttribute != null) {
			weight = example.getValue(weightAttribute);
		}
		int label = (int)example.getValue(labelAttribute);
		leftWeight += weight;
		rightWeight -= weight;
		leftLabelWeights[label] += weight;
		rightLabelWeights[label] -= weight;
	}
	
	public double getIncrementalBenefit() {
		return 0;
	}
	
	
	/**
	 * This method returns the criterion specified by the respective parameters.
	 */
	public static Criterion createCriterion(ParameterHandler handler, double minimalGain) throws OperatorException {
		String criterionName = handler.getParameterAsString(PARAMETER_CRITERION);
		Class criterionClass = null;
		for (int i = 0; i < CRITERIA_NAMES.length; i++) {
			if (CRITERIA_NAMES[i].equals(criterionName)) {
				criterionClass = CRITERIA_CLASSES[i];
			}
		}

		if ((criterionClass == null) && (criterionName != null)) {
			try {
				criterionClass = Tools.classForName(criterionName);
			} catch (ClassNotFoundException e) {
				throw new OperatorException("Cannot find criterion '"+criterionName+"' and cannot instantiate a class with this name.");
			}
		}

		if (criterionClass != null) {
			try {
				Criterion criterion = (Criterion)criterionClass.newInstance();
				if (criterion instanceof MinimalGainHandler) {
					((MinimalGainHandler)criterion).setMinimalGain(minimalGain);
				}
				return criterion;
			} catch (InstantiationException e) {
				throw new OperatorException("Cannot instantiate criterion class '"+criterionClass.getName()+"'.");
			} catch (IllegalAccessException e) {
				throw new OperatorException("Cannot access criterion class '"+criterionClass.getName()+"'.");
			}
		} else {
			throw new OperatorException("No relevance criterion defined.");
		}
	}

}