package net.bmahe.genetics4j.core.combination;
   
   import java.util.ArrayList;
   import java.util.Collections;
   import java.util.List;
   import java.util.Objects;
   
   import org.apache.commons.lang3.Validate;
   
  import net.bmahe.genetics4j.core.Genotype;
  import net.bmahe.genetics4j.core.chromosomes.Chromosome;
  import net.bmahe.genetics4j.core.spec.AbstractEAConfiguration;
  import net.bmahe.genetics4j.core.util.MultiIntCounter;
  
  /**
   * Produces the cartesian product of all chromosome combinations across all chromosome positions.
   *
   * @author bruno
   *
   */
  public class AllCasesGenotypeCombinator implements GenotypeCombinator {
  
  	@Override
  	public List<Genotype> combine(final AbstractEAConfiguration eaConfiguration,
  			final List<List<Chromosome>> chromosomes) {
  		Objects.requireNonNull(eaConfiguration);
  		Objects.requireNonNull(chromosomes);
  		Validate.isTrue(eaConfiguration.chromosomeSpecs().size() == chromosomes.size());
  
  		boolean hasChild = true;
  		for (int i = 0; i < chromosomes.size() && hasChild; i++) {
  			final List<Chromosome> list = chromosomes.get(i);
  
  			if (list.isEmpty()) {
  				hasChild = false;
  			}
  		}
  		if (hasChild == false) {
  			return Collections.emptyList();
  		}
  
  		final int[] maxIndices = chromosomes.stream().mapToInt(List::size).toArray();
  
  		final MultiIntCounter multiIntCounter = new MultiIntCounter(maxIndices);
  
  		boolean done = false;
  		final List<Genotype> combined = new ArrayList<>();
  		while (done == false) {
  
  			final List<Chromosome> currentGenotype = new ArrayList<>();
  
  			for (int i = 0; i < chromosomes.size(); i++) {
  				final int index = multiIntCounter.getIndex(i);
  				currentGenotype.add(chromosomes.get(i).get(index));
  			}
  			combined.add(new Genotype(currentGenotype));
  
  			multiIntCounter.next();
  			if (multiIntCounter.hasNext() == false) {
  				done = true;
  			}
  		}
  
  		return combined;
  	}
  }