package net.bmahe.genetics4j.core.spec.selection;
   
   import java.util.Comparator;
   
   import org.immutables.value.Value;
   
   import net.bmahe.genetics4j.core.Individual;
   
   @Value.Immutable
  public abstract class Tournament<T extends Comparable<T>> implements SelectionPolicy {
  
  	@Value.Parameter
  	public abstract int numCandidates();
  
  	@Value.Default
  	public Comparator<Individual<T>> comparator() {
  		return Comparator.comparing(Individual::fitness);
  	}
  
  	/*
  	 * TODO: Enabling this makes immutables create non-compilable code
  	 * 
  	 * @Value.Check protected void check() { Validate.isTrue(numCandidates() > 0); }
  	 */
  
  	public static class Builder<T extends Comparable<T>> extends ImmutableTournament.Builder<T> {
  	}
  
  	public static <U extends Comparable<U>> Tournament<U> of(final int numCandidates) {
  		return ImmutableTournament.of(numCandidates);
  	}
  
  	public static <U extends Comparable<U>> Tournament<U> of(final int numCandidates,
  			final Comparator<Individual<U>> comparator) {
  		return new Builder<U>().numCandidates(numCandidates)
  				.comparator(comparator)
  				.build();
  	}
  
  }