package t234;

/**
 * Represents nodes with only 2 subtrees of a 2-3-4 tree.
 * It contains the data object, a left Tree234 and a right Tree234.
 *
 * @since 04/18/01
 * @author Dung X. Nguyen, Copyright 2000 - All Rights Reserved.
 * @author Alan L. Cox
 */
class Node2 extends ANode234
{
  // Data invariant: _leftTree != null
  private Tree234 _leftTree = new Tree234();

  // Data invariant: _data != null
  private Integer _data;

  // Data invariant: _rightTree != null
  private Tree234 _rightTree = new Tree234();

  /**
   * Initializes this Node2 to contain n and two empty subtrees.
   * @param n != null
   */
  Node2(Integer n)
  {
    _data = n;
  }

  /**
   * Initializes this Node2 to contain the given data and the given
   * left and right subtrees. 
   *
   * @param lTree != null the left subtree,
   *                      all elements in lTree are less than n.
   * @param n != null less than all elements in rTree.
   * @param rTree != null the right subtree
   */
  Node2(Tree234 lTree, Integer n, Tree234 rTree)
  {
    _data      = n;
    _leftTree  = lTree;
    _rightTree = rTree;
  }

  final boolean isEmpty(Tree234 owner)
  {
    return false;
  }

  final void insert(Tree234 owner, Integer n)
  {
    int dataVal = _data.intValue();
    int key     = n.intValue();

    if (key != dataVal) {
      if (_leftTree.isEmpty() && _rightTree.isEmpty()) { // leaf node.
	owner.changeRoot(new Node3(n, _data));
      }
      else { //owner is parent of left and right subtrees.
	if (key < dataVal)
	  _leftTree.insertHelper(owner, n);
	else // (dataVal < key)
	  _rightTree.insertHelper(owner, n);
      }
    }
  }

  final void insertHelper(Tree234 ownerPo, Tree234 owner, Integer n)
  {
    owner.insert(n);	// can call insert(owner, n) instead.
  }

  final void attach(Tree234 owner, Tree234 lTree, Integer n, Tree234 rTree)
  {
    Node3 topNode;

    if (n.intValue() < _data.intValue()) {
      topNode = new Node3(lTree, n, rTree, _data, _rightTree);
    }
    else {
      topNode = new Node3(_leftTree, _data, lTree, n, rTree);
    }
    owner.changeRoot(topNode);
  }

  final void drawRootAndSubtrees(int level)
  {
    System.out.println(_data);
    _leftTree.drawAtLevel(level + 1);
    System.out.println();
    _rightTree.drawAtLevel(level + 1);
  }
}