/*
 * Encog(tm) Core v3.4 - Java Version
 * http://www.heatonresearch.com/encog/
 * https://github.com/encog/encog-java-core
 
 * Copyright 2008-2016 Heaton Research, Inc.
 *
 * 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 at
 *
 *     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.
 *   
 * For more information on Heaton Research copyrights, licenses 
 * and trademarks visit:
 * http://www.heatonresearch.com/copyright
 */
package org.encog.ml.ea.score.parallel;

import java.util.List;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import org.encog.ml.CalculateScore;
import org.encog.ml.ea.codec.GeneticCODEC;
import org.encog.ml.ea.genome.Genome;
import org.encog.ml.ea.population.Population;
import org.encog.ml.ea.score.AdjustScore;
import org.encog.ml.ea.species.Species;
import org.encog.ml.genetic.GeneticError;
import org.encog.util.concurrency.MultiThreadable;

/**
 * This class is used to calculate the scores for an entire population. This is
 * typically done when a new population must be scored for the first time.
 */
public class ParallelScore implements MultiThreadable {
	/**
	 * The population to score.
	 */
	private final Population population;
	
	/**
	 * The CODEC used to create genomes.
	 */
	private final GeneticCODEC codec;
	
	/**
	 * The scoring function.
	 */
	private final CalculateScore scoreFunction;
	
	/**
	 * The score adjuster.
	 */
	private final List adjusters;
	
	/**
	 * The number of requested threads.
	 */
	private int threads;
	
	/**
	 * The actual number of threads.
	 */
	private int actualThreads;

	/**
	 * An error from one of the threads.
	 */
	private Exception reportedError;

	/**
	 * Construct the parallel score calculation object.
	 * @param thePopulation The population to score.
	 * @param theCODEC The CODEC to use.
	 * @param theAdjusters The score adjusters to use.
	 * @param theScoreFunction The score function.
	 * @param theThreadCount The requested thread count.
	 */
	public ParallelScore(Population thePopulation, GeneticCODEC theCODEC,
			List theAdjusters, CalculateScore theScoreFunction,
			int theThreadCount) {
		this.codec = theCODEC;
		this.population = thePopulation;
		this.scoreFunction = theScoreFunction;
		this.adjusters = theAdjusters;
		this.actualThreads = 0;
	}

	/**
	 * @return the population
	 */
	public Population getPopulation() {
		return population;
	}

	/**
	 * @return the scoreFunction
	 */
	public CalculateScore getScoreFunction() {
		return scoreFunction;
	}

	/**
	 * @return the codec
	 */
	public GeneticCODEC getCodec() {
		return codec;
	}

	/**
	 * Calculate the scores.
	 */
	public void process() {
		// determine thread usage
		if (this.scoreFunction.requireSingleThreaded()) {
			this.actualThreads = 1;
		} else if (threads == 0) {
			this.actualThreads = Runtime.getRuntime().availableProcessors();
		} else {
			this.actualThreads = threads;
		}

		// start up
		ExecutorService taskExecutor = null;

		if (this.threads == 1) {
			taskExecutor = Executors.newSingleThreadScheduledExecutor();
		} else {
			taskExecutor = Executors.newFixedThreadPool(this.actualThreads);
		}

		for (Species species : this.population.getSpecies()) {
			for (Genome genome : species.getMembers()) {
				taskExecutor.execute(new ParallelScoreTask(genome, this));
			}
		}

		taskExecutor.shutdown();
		try {
			taskExecutor.awaitTermination(Long.MAX_VALUE, TimeUnit.MINUTES);
		} catch (InterruptedException e) {
			throw new GeneticError(e);
		}

		if( this.reportedError!=null ) {
			throw new GeneticError(this.reportedError);
		}
	}

	/**
	 * @return The score adjusters.
	 */
	public List getAdjusters() {
		return this.adjusters;
	}

	/**
	 * @return The desired number of threads.
	 */
	@Override
	public int getThreadCount() {
		return this.threads;
	}

	/**
	 * @param numThreads The desired thread count.
	 */
	@Override
	public void setThreadCount(int numThreads) {
		this.threads = numThreads;
	}

	public void reportError(Exception ex) {
		this.reportedError = ex;
	}
}