/*
 *  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.tools.math.optimization.ec.es;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.Iterator;

import com.rapidminer.operator.performance.PerformanceVector;
import com.rapidminer.tools.Tools;


/**
 * A set of individuals. Each individual contains the values vector and
 * information about its fitness.
 * 
 * @author Ingo Mierswa
 * @version $Id: Population.java,v 1.3 2008/05/09 19:23:16 ingomierswa Exp $
 */
public class Population {

    public static final Comparator<Individual> PERFORMANCE_COMPARATOR = new Comparator<Individual>() {

        public int compare(Individual i1, Individual i2) {
            PerformanceVector p1 = i1.getFitness();
            PerformanceVector p2 = i2.getFitness();
            return p1.compareTo(p2);
        }
    };
    
	/** List of individuals. */
	private ArrayList<Individual> individuals = new ArrayList<Individual>();

	/** All generations' best individual. */
	private Individual bestEver;

	/** The currently best individual. */
	private Individual currentBest;

	/** The number of generations. */
	private int generations = 1;

	/** The last generation where setBestEver() was invoked. */
	private int lastImprovement = 1;

	/** Removes all individuals. */
	public void clear() {
		individuals.clear();
	}

	/** Adds a single individual. */
	public void add(Individual individual) {
		individuals.add(individual);
	}

	/** Adds all individuals from the given collection. */
	public void addAll(Collection<Individual> newIndividuals) {
		individuals.addAll(newIndividuals);
	}

	/** Removes a single individual. */
	public void remove(Individual individual) {
		individuals.remove(individual);
	}

	/** Removes a single individual. */
	public void remove(int i) {
		individuals.remove(i);
	}

	/** Returns a single individual. */
	public Individual get(int i) {
		return individuals.get(i);
	}

	/** Returns the number of all individuals. */
	public int getNumberOfIndividuals() {
		return individuals.size();
	}

	public void setCurrentBest(Individual currentBest) {
		this.currentBest = currentBest;
	}

	public Individual getCurrentBest() {
		return this.currentBest;
	}

	public void setBestEver(Individual bestEver) {
		this.lastImprovement = generations;
		this.bestEver = bestEver;
	}

	public Individual getBestEver() {
		return bestEver;
	}

	public void nextGeneration() {
		this.generations++;
	}

	public int getGeneration() {
		return generations;
	}

	public int getGenerationsWithoutImprovement() {
		return (generations - lastImprovement);
	}

    /**
     * Sorts the individuals in ascending order according to their performance,
     * thus the best one will be in last position.
     */
    public void sort() {
        Collections.sort(individuals, PERFORMANCE_COMPARATOR);
    }

    /**
     * Sorts the individuals in ascending order according to their performance,
     * thus the best one will be in last position.
     */
    public void sort(Comparator<Individual> comparator) {
        Collections.sort(individuals, comparator);
    }
    
	public String toString() {
		StringBuffer result = new StringBuffer("Population in generation " + generations + ":" + Tools.getLineSeparator());
		Iterator i = individuals.iterator();
		while (i.hasNext()) {
			result.append(i.next() + Tools.getLineSeparator());
		}
		return result.toString();
	}
}