package net.bmahe.genetics4j.core.spec.mutation;
   
   import java.util.Objects;
   
   import org.apache.commons.lang3.Validate;
   import org.immutables.value.Value;
   
   /**
    * Applies another mutation policy repeatedly.
   *
   * <p>The number of repetitions is selected uniformly between {@link #minRepetitions()} and
   * {@link #maxRepetitions()}, inclusive, for each genotype. Equal bounds define a fixed number of repetitions.
   */
  @Value.Immutable
  public abstract class RepeatedMutation implements MutationPolicy {
  
  	@Value.Parameter
  	public abstract int minRepetitions();
  
  	@Value.Parameter
  	public abstract int maxRepetitions();
  
  	@Value.Parameter
  	public abstract MutationPolicy mutationPolicy();
  
  	@Value.Check
  	protected void check() {
  		Validate.isTrue(minRepetitions() > 0);
  		Validate.isTrue(maxRepetitions() >= minRepetitions());
  		Objects.requireNonNull(mutationPolicy());
  	}
  
  	public static class Builder extends ImmutableRepeatedMutation.Builder {
  	}
  
  	public static Builder builder() {
  		return new Builder();
  	}
  
  	/**
  	 * Creates a mutation policy with a fixed number of repetitions.
  	 *
  	 * @param repetitions    number of times to apply the mutation policy
  	 * @param mutationPolicy mutation policy to repeat
  	 * @return a repeated mutation policy
  	 */
  	public static RepeatedMutation ofExactly(final int repetitions, final MutationPolicy mutationPolicy) {
  		return ImmutableRepeatedMutation.of(repetitions, repetitions, mutationPolicy);
  	}
  
  	/**
  	 * Creates a mutation policy with a number of repetitions selected uniformly between one and the specified maximum,
  	 * inclusive.
  	 *
  	 * @param maxRepetitions maximum number of repetitions, inclusive
  	 * @param mutationPolicy mutation policy to repeat
  	 * @return a repeated mutation policy
  	 */
  	public static RepeatedMutation ofUpTo(final int maxRepetitions, final MutationPolicy mutationPolicy) {
  		return ImmutableRepeatedMutation.of(1, maxRepetitions, mutationPolicy);
  	}
  
  	/**
  	 * Creates a mutation policy with a variable number of repetitions.
  	 *
  	 * @param minRepetitions minimum number of repetitions, inclusive
  	 * @param maxRepetitions maximum number of repetitions, inclusive
  	 * @param mutationPolicy mutation policy to repeat
  	 * @return a repeated mutation policy
  	 */
  	public static RepeatedMutation of(final int minRepetitions, final int maxRepetitions,
  			final MutationPolicy mutationPolicy) {
  		return ImmutableRepeatedMutation.of(minRepetitions, maxRepetitions, mutationPolicy);
  	}
  }