/*
 * Copyright 2007-2013
 * Licensed under GNU Lesser General Public License
 * 
 * This file is part of EpochX
 * 
 * EpochX 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 3 of the License, or
 * (at your option) any later version.
 * 
 * EpochX 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 EpochX. If not, see <http://www.gnu.org/licenses/>.
 * 
 * The latest version is available from: http://www.epochx.org
 */

package org.epochx.ge.stats;

import java.util.Arrays;

import org.epochx.Individual;
import org.epochx.Population;
import org.epochx.event.GenerationEvent.EndGeneration;
import org.epochx.event.stat.AbstractStat;
import org.epochx.ge.GEIndividual;
import org.epochx.grammar.NonTerminalSymbol;

/**
 * A stat that returns the depth of all parse trees in the population from
 * the previous generation. All individuals in the population must be instances 
 * of <code>GEIndividual</code>.
 * 
 * @since 2.0
 */
public class GenerationDepths extends AbstractStat<EndGeneration> {

	private int[] depths;

	/**
	 * Constructs a <code>GenerationDepths</code> stat and registers 
	 * its dependencies
	 */
	public GenerationDepths() {
		super(NO_DEPENDENCIES);
	}

	/**
	 * Triggers the generation of an updated value for this stat. Once this stat
	 * has been registered, this method will be called on each
	 * <code>EndGeneration</code> event.
	 * 
	 * @param event an object that encapsulates information about the event that
	 *        occurred
	 */
	@Override
	public void refresh(EndGeneration event) {
		Population population = event.getPopulation();
		depths = new int[population.size()];
		int index = 0;

		for (Individual individual: population) {
			if (individual instanceof GEIndividual) {
				NonTerminalSymbol parseTree = ((GEIndividual) individual).getParseTree();
				int depth = -1;
				if (parseTree != null) {
					depth = parseTree.getDepth();
				}
				
				depths[index++] = depth;
			}
		}
	}
	
	/**
	 * Returns an array of the depths of each parse tree in the population 
	 * from the previous generation
	 * 
	 * @return the depths of each parse tree in the previous generation
	 */
	public int[] getDepths() {
		return depths;
	}

	/**
	 * Returns a string representation of the value of this stat
	 * 
	 * @return a <code>String</code> that represents the value of this stat
	 */
	@Override
	public String toString() {
		return Arrays.toString(depths);
	}
}