/**
 * This class implements a subset from an existing set.  It's slow and 
 * inefficient because I didn't have time to write anything better.
 * @author Gary Yngve
 * @version 2/10/06
 */

// TODO: WRITE JAVADOC

import java.util.Comparator;
import java.util.NoSuchElementException;

public class BasicOrderedSubTreeSet implements BasicOrderedSet {
  
  BasicOrderedSet originalSet;
  Object min, max;

  private BasicOrderedSubTreeSet() {}

  public BasicOrderedSubTreeSet(BasicOrderedSet originalSet, 
                                Object min, Object max) {
    this.originalSet = originalSet;
    this.min = min;
    this.max = max;
  }

  public boolean contains(Comparable o) {
     if (originalSet.comparator().compare(o,min) < 0 ||
         originalSet.comparator().compare(o,max) >= 0)
       return false;
     else 
       return originalSet.contains(o);
  }

  public boolean add(Comparable o) {
     if (originalSet.comparator().compare(o,min) < 0 ||
         originalSet.comparator().compare(o,max) >= 0)
     throw new IllegalArgumentException("inserting out of range");
     return originalSet.add(o);
  }

  public int size() {
    int count = 0;
    for(BasicSetIterator it = iterator(); it.hasNext(); ) {
      it.next();
      count++;
    }
    return count;
  }

  public boolean remove(Comparable o) {
    throw new UnsupportedOperationException();
  }

  public BasicOrderedSet subSet(Object newmin, Object newmax) {
    if (originalSet.comparator().compare(newmin,newmax) >= 0)
      throw new IllegalArgumentException("inverted range");
    if (originalSet.comparator().compare(newmin,min) < 0)
      throw new IllegalArgumentException("lower bound too low");
    if (originalSet.comparator().compare(max,newmax) < 0)
      throw new IllegalArgumentException("upper bound too high");
      return new BasicOrderedSubTreeSet(originalSet, newmin, newmax);
  }

  public Comparator comparator() {
    return originalSet.comparator();
  }

  public BasicSetIterator iterator() {
    return new BasicOrderedSubTreeSetIterator();
  }

  private class BasicOrderedSubTreeSetIterator implements BasicSetIterator {
    BasicSetIterator it;
    boolean cached;
    boolean cachedBool;
    Comparable cachedObj;

    BasicOrderedSubTreeSetIterator() {
      it = originalSet.iterator();
    }

    public boolean hasNext() {
      if (cached) return cachedBool;
      cached = true;
      while(it.hasNext()) {
        Comparable o = it.next();
        if (originalSet.comparator().compare(o,min) >= 0 &&
            originalSet.comparator().compare(o,max) < 0) {
          cachedObj = o;
          cachedBool = true;
          return true;
        }
      }
      cachedBool = false;
      return false;
    }

    public Comparable next() {
      if (!hasNext()) throw new NoSuchElementException();
      cached = false;
      return cachedObj;
    }
  }

}