/*
 * (c) Copyright 2007, 2008, 2009 Hewlett-Packard Development Company, LP
 * All rights reserved.
 * [See end of file]
 */

package structure.avl;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.NoSuchElementException;

public class AvlIterator<R extends Comparable<? super R>> implements Iterator<R>
{
    public static <R extends Comparable<? super R>> Iterator<R> iterator(AVL<R> avl, R min, R max)
    {
        return new AvlIterator<R>(avl, min, max) ;
    }

    boolean finished = false ;
    R record ;              // Yield this before moving on
    AvlNode<R> node ;
    R max ;

    AvlIterator(AVL<R> avl, R min, R max)
    {
        if ( min != null && max != null )
        {
            int x = min.compareTo(max) ;
            if ( x >= 0 )
            {
                finished = true ;
                return ;
            }
        }
        
        node = avl.findNodeAbove(min) ;
        if ( node == null )
        {
            record = null ;
            finished = true ;
            return ; 
        }

        record = node.record ;
        this.max = max ;
    }

    @Override
    public boolean hasNext()
    {
        if ( finished )
            return false ;

        if ( record != null )
            return true ;

        // Record null, move to next node. 
        if ( node == null )
        {
            System.err.println("Happened!") ;
            // Does not happen?
            finished = true ;
            return false ;
        }

        // Have yielded the value for "node" (and hence all left subtree) 
        // Move the left-est node of the right subtree.
        // If no right subtree
        //   Go up to parent.
        //   Check we were the left subtree of parent, not right.
        // If no parent (this is the root), and we were left of parent,
        //   go down 
        
        AvlNode<R> nextNode = node.right ;
        if ( nextNode != null )
        {
            // There is a right tree to do.
            // Find min (left chasing)
            while ( nextNode.left != null )
                nextNode = nextNode.left ; 
        }
        else   
        {
            // No right subtree from here.
            // Walk up tree until we were not the right node of our parent.
            AvlNode<R> n2 = node ;
            AvlNode<R> n3 = n2.parent ;
            while( n3 != null )
            {
                if ( n3.right != n2 )
                {
                    n2 = n3 ;
                    break ;
                }
           
                n2 = n3 ;
                n3 = n2.parent ;
            }
            
            if ( n3 == null )
            {
                finished = true ;
                return false ;
            }
            
            // Now at the first node upwards when we're the left
            // (i.e. less than the value)
            
            nextNode = n2 ;
        }
        
        node = nextNode ;
        return testAndSetRecord(nextNode) ;
    }

    private boolean testAndSetRecord(AvlNode<R> node)
    {
        if ( node == null )
        {
            record = null ;
            finished = true ;
            return false ;
        }

        if ( max != null )
        {
            int x = node.record.compareTo(max) ;
            if ( x >= 0 )
            {
                // End
                finished = true ;
                return false ;
            }
        }
        record = node.record ;
        return true ;
    }

    @Override
    public R next()
    {
        if ( ! hasNext())
            throw new NoSuchElementException("AvlIterator") ;
        R r = record ;
        record = null ;  
        return r ;
    }

    @Override
    public void remove()
    { throw new UnsupportedOperationException("AvlIterator") ; }

    // Calculate the iterator.  For testing. 
    static <R extends Comparable<? super R>> List<R> calcIter(AvlNode<R> node, R min, R max)
    {
        List<R> x = new ArrayList<R>() ;
        if ( node == null )
            return x ;
        node.records(x) ; // Sorted.
        if ( min != null )
            while ( x.size() > 0 && x.get(0).compareTo(min) < 0 )
                x.remove(0) ;
        
        if ( max != null )
            while ( x.size() > 0 && x.get(x.size()-1).compareTo(max) >= 0 )
                x.remove(x.size()-1) ; 
        return x ;
    }

}

/*
 * (c) Copyright 2007, 2008, 2009 Hewlett-Packard Development Company, LP
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */