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/**
 * Copyright (C) 2010-2018 Gordon Fraser, Andrea Arcuri and EvoSuite
 * contributors
 *
 * This file is part of EvoSuite.
 *
 * EvoSuite 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 3.0 of the License, or
 * (at your option) any later version.
 *
 * EvoSuite 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 Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with EvoSuite. If not, see .
 */
package org.evosuite.ga.metaheuristics.mulambda;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import org.evosuite.ga.Chromosome;
import org.evosuite.ga.ChromosomeFactory;
import org.evosuite.ga.FitnessFunction;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * (Mu, Lambda) EA
 *
 * @author José Campos
 */
public class MuLambdaEA extends AbstractMuLambda {

  private static final long serialVersionUID = -1104094637643130537L;

  private static final Logger logger = LoggerFactory.getLogger(MuLambdaEA.class);

  public MuLambdaEA(ChromosomeFactory factory, int mu, int lambda) {
    super(factory, mu, lambda);
  }

  /** {@inheritDoc} */
  @SuppressWarnings("unchecked")
  @Override
  protected void evolve() {

    List offspring = new ArrayList(this.lambda);

    // create new offspring by mutating current population
    for (int i = 0; i < this.mu; i++) {
      for (int j = 0; j < this.lambda / this.mu; j++) {
        T t = (T) this.population.get(i).clone();

        do {
          this.notifyMutation(t);
          t.mutate();
        } while (!t.isChanged());

        offspring.add(t);
      }
    }

    // update fitness values of offspring
    for (T t : offspring) {
      for (FitnessFunction fitnessFunction : this.fitnessFunctions) {
        fitnessFunction.getFitness(t);
        this.notifyEvaluation(t);
      }
    }

    if (this.getFitnessFunction().isMaximizationFunction()) {
      // this if condition assumes *all* fitness functions are either to be maximized or to be
      // minimized

      // sort offspring from the one with the highest fitness value to the one with the lowest
      // fitness value
      Collections.sort(offspring, Collections.reverseOrder());
    } else {
      // sort offspring from the one with the lowest fitness value to the one with the highest
      // fitness value
      Collections.sort(offspring);
    }

    // replace mu (i.e., population) out of lambda (i.e., offspring)
    for (int i = 0; i < this.population.size(); i++) {
      logger.debug("replacing " + this.population.get(i).getFitness() + " with "
          + offspring.get(i).getFitness());
      this.population.set(i, offspring.get(i));
    }
  }
}