package net.bmahe.genetics4j.core.spec.replacement;
   
   import org.apache.commons.lang3.Validate;
   import org.immutables.value.Value;
   
   import net.bmahe.genetics4j.core.spec.replacement.ImmutableDeleteNLast;
   import net.bmahe.genetics4j.core.spec.selection.SelectionPolicy;
   
   /**
   * Delete N Last
   * <p>
   * This replacement strategy deletes the N weakest individuals and replace them
   * with the best offsprings
   * 
   */
  @Value.Immutable
  public interface DeleteNLast extends ReplacementStrategy {
  
  	static final double DEFAULT_WEAK_RATIO = 0.05;
  
  	/**
  	 * How many weakest individuals to consider for replacement
  	 * 
  	 * @return
  	 */
  	@Value.Default
  	@Value.Parameter
  	default double weakRatio() {
  		return DEFAULT_WEAK_RATIO;
  	}
  
  	/**
  	 * Describe which offsprings to select for the next generation
  	 * 
  	 * @return
  	 */
  	@Value.Parameter
  	public abstract SelectionPolicy offspringSelectionPolicy();
  
  	@Value.Check
  	default void check() {
  		Validate.inclusiveBetween(0.0, 1.0, weakRatio());
  	}
  
  	class Builder extends ImmutableDeleteNLast.Builder {
  	}
  
  	static Builder builder() {
  		return new Builder();
  	}
  
  	static DeleteNLast of(final double weakRatio, final SelectionPolicy selectionPolicy) {
  		return builder().weakRatio(weakRatio).offspringSelectionPolicy(selectionPolicy).build();
  	}
  }