package net.bmahe.genetics4j.core.evaluation;
   
   import java.util.List;
   import java.util.Objects;
   import java.util.concurrent.CompletableFuture;
   import java.util.concurrent.ExecutorService;
   
   import org.apache.commons.lang3.Validate;
   import org.apache.logging.log4j.LogManager;
  import org.apache.logging.log4j.Logger;
  
  import net.bmahe.genetics4j.core.FitnessBulkAsync;
  import net.bmahe.genetics4j.core.Genotype;
  import net.bmahe.genetics4j.core.spec.EAConfigurationBulkAsync;
  
  /**
   * Wrapper around {@link net.bmahe.genetics4j.core.FitnessBulkAsync} for computing the fitness of a population
   *
   * @param <T>
   */
  public class FitnessEvaluatorBulkAsync<T extends Comparable<T>> implements FitnessEvaluator<T> {
  
  	public static final Logger logger = LogManager.getLogger(FitnessEvaluatorBulkAsync.class);
  
  	private final EAConfigurationBulkAsync<T> eaConfigurationBulkAsync;
  
  	private final ExecutorService executorService;
  
  	public FitnessEvaluatorBulkAsync(final EAConfigurationBulkAsync<T> _eaConfigurationBulkAsync,
  			final ExecutorService _executorService) {
  		Objects.requireNonNull(_eaConfigurationBulkAsync);
  		Objects.requireNonNull(_executorService);
  
  		this.eaConfigurationBulkAsync = _eaConfigurationBulkAsync;
  		this.executorService = _executorService;
  	}
  
  	@Override
  	public List<T> evaluate(final long generation, final List<Genotype> genotypes) {
  		Validate.isTrue(generation >= 0);
  		Objects.requireNonNull(genotypes);
  		Validate.isTrue(genotypes.isEmpty() == false, "genotypes cannot be empty");
  
  		final FitnessBulkAsync<T> fitnessBulkAsync = eaConfigurationBulkAsync.fitness();
  
  		logger.trace("Submitting fitness computation task");
  		final CompletableFuture<List<T>> fitnessesCF = fitnessBulkAsync.compute(executorService, genotypes);
  
  		return fitnessesCF.join();
  	}
  }