package com.github.lstephen.ai.search;
   
   import java.util.List;
   import java.util.function.Supplier;
   import java.util.stream.Collectors;
   import java.util.stream.Stream;
   
   import com.google.common.base.Preconditions;
   
  /**
   *
   */
  public final class RepeatedHillClimbing<S> {
  
    private static final Integer REPEATS = 5;
  
    private final Supplier<S> initialFactory;
  
    private final HillClimbing<S> hillClimbing;
  
    public RepeatedHillClimbing(Supplier<S> initialFactory, HillClimbing<S> hillClimbing) {
      Preconditions.checkNotNull(initialFactory);
      Preconditions.checkNotNull(hillClimbing);
  
      this.initialFactory = initialFactory;
      this.hillClimbing = hillClimbing;
    }
  
    public S search() {
      List<S> initial = Stream
        .generate(initialFactory)
        .limit(REPEATS)
        .collect(Collectors.toList());
  
      return initial
        .parallelStream()
        .map(hillClimbing::search)
        .max(hillClimbing.getHeuristic())
        .orElseThrow(() -> new IllegalStateException("Could not find final result"));
    }
  
  }