/*
 *  RapidMiner
 *
 *  Copyright (C) 2001-2008 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.features.construction;

import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;

import com.rapidminer.example.Attribute;
import com.rapidminer.example.Tools;
import com.rapidminer.example.set.AttributeWeightedExampleSet;
import com.rapidminer.generator.FeatureGenerator;
import com.rapidminer.generator.GenerationException;
import com.rapidminer.operator.features.Individual;
import com.rapidminer.operator.features.IndividualOperator;
import com.rapidminer.tools.RandomGenerator;


/**
 * The mutation operator for YAGGA. This operator adds single attributes from
 * the original set, creates new ones and deselect single attributes.
 * 
 * @see YAGGA
 * @author Ingo Mierswa, Simon Fischer
 * @version $Id: GeneratingMutation.java,v 1.1 2006/04/14 07:47:17 ingomierswa
 *          Exp $
 */
public class GeneratingMutation extends IndividualOperator {

	private List<FeatureGenerator> generators;

	private List<Attribute> originalAttributes;

	private double prob;

	private int maxNumberOfAttributes;
	
	private RandomGenerator random;

	private int maxDepth = -1;

	private String[] unusedFunctions = new String[0];

	public GeneratingMutation(List<Attribute> originalAttributes, double prob, int maxNumberOfAttributes, List<FeatureGenerator> generators, RandomGenerator random) {
		this.originalAttributes = originalAttributes;
		this.prob = prob;
		this.maxNumberOfAttributes = maxNumberOfAttributes;
		this.generators = generators;
        this.random = random;
	}

	public void setMaxConstructionDepth(int maxDepth) {
		this.maxDepth = maxDepth;
	}

	public void setUnusedFunctions(String[] functions) {
		this.unusedFunctions = functions;
	}

	/**
	 * Performs one of the following three mutations:
	 * <ul>
	 * <li>add a newly generated attribute</li>
	 * <li>add an original attribute</li>
	 * <li>remove an attribute</li>
	 * </ul>
	 */
	public List<Individual> operate(Individual individual) throws Exception {
		List<Individual> l = new LinkedList<Individual>();
		AttributeWeightedExampleSet clone = (AttributeWeightedExampleSet) individual.getExampleSet().clone();
		double p = prob < 0 ? 1.0d / clone.getAttributes().size() : prob;
		p /= 4.0d;
		try {
			if ((maxNumberOfAttributes < 0) || (clone.getAttributes().size() < maxNumberOfAttributes)) {
				addOriginalAttribute(clone, p);
			}
			boolean generationPossible = false;
			if ((maxNumberOfAttributes < 0) || (clone.getAttributes().size() <= maxNumberOfAttributes)) {
				generationPossible = addGeneratedAttribute(clone, p);
			}
			deselect(clone, generationPossible ? 2 : 1, p);
		} catch (GenerationException e) {
			individual.getExampleSet().getLog().logWarning("GeneratingMutation: Exception occured during generation of attributes, using only original example set instead.");
		}

		if (clone.getNumberOfUsedAttributes() > 0) {
			l.add(new Individual(clone));
		}
		l.add(individual);
		return l;
	}

	/** Adds a new attribute. Returns true, if generation was possible. */
	private boolean addGeneratedAttribute(AttributeWeightedExampleSet exampleSet, double p) throws Exception {
		if (random.nextDouble() < p) {
			FeatureGenerator generator = FeatureGenerator.selectGenerator(exampleSet, generators, maxDepth, unusedFunctions, random);
			if (generator != null) {
				generator = generator.newInstance();
				Attribute[] args = Tools.getRandomCompatibleAttributes(exampleSet, generator, maxDepth, unusedFunctions, random);
				generator.setArguments(args);
				List<FeatureGenerator> generatorList = new LinkedList<FeatureGenerator>();
				generatorList.add(generator);
				List<Attribute> newAttributes = FeatureGenerator.generateAll(exampleSet.getExampleTable(), generatorList);
				for (Attribute newAttribute : newAttributes)
					exampleSet.getAttributes().addRegular(newAttribute);
				return true;
			} else
				return false;
		} else
			return false;
	}

	private void addOriginalAttribute(AttributeWeightedExampleSet exampleSet, double p) {
		if (random.nextDouble() < p) {
			int i = random.nextInt(originalAttributes.size());
			Attribute originalAttribute = originalAttributes.get(i);
			if (exampleSet.getAttributes().get(originalAttribute.getName()) == null)
				exampleSet.getAttributes().addRegular(originalAttribute);
		}
	}

	private void deselect(AttributeWeightedExampleSet exampleSet, int m, double p) {
		Iterator<Attribute> i = exampleSet.getAttributes().iterator();
		while (i.hasNext()) {
			i.next();
			if (random.nextDouble() < m * p / originalAttributes.size()) {
				i.remove();
			}
		}
	}
}