/*
 * Copyright (c) 1998-2006 Caucho Technology -- all rights reserved
 *
 * This file is part of Resin(R) Open Source
 *
 * Each copy or derived work must preserve the copyright notice and this
 * notice unmodified.
 *
 * Resin Open Source is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * Resin Open Source is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE, or any warranty
 * of NON-INFRINGEMENT.  See the GNU General Public License for more
 * details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Resin Open Source; if not, write to the
 *   Free SoftwareFoundation, Inc.
 *   59 Temple Place, Suite 330
 *   Boston, MA 02111-1307  USA
 *
 * @author Scott Ferguson
 */

package com.caucho.xml;

import java.io.*;
import org.w3c.dom.*;
import com.caucho.vfs.*;

class QDeepNodeList implements NodeList {
  QNode _top;
  QNodePredicate _predicate;
  QAbstractNode _first;
  QAbstractNode _node;
  int _index = -2;
  int _length = -2;
  int _changeCount;

  QDeepNodeList(QNode top, QAbstractNode first, QNodePredicate predicate)
  {
    _top = top;
    _first = first;
    _predicate = predicate;
  }

  public Node item(int index)
  {
    QAbstractNode next = _node;

    int i = _index;

    if (next == null || index < i ||
        _changeCount != _top._owner._changeCount) {
      _changeCount = _top._owner._changeCount;
      next = _first;

      if (_predicate != null && next != null && _predicate.isMatch(next))
	i = 0;
      else
	i = -1;
    }

    QAbstractNode end = getEnd();
    while (i < index && next != end) {
      next = next.getNextPreorder();
      if (next != end && _predicate.isMatch(next)) {
	i++;
      }
    }

    if (next == end) {
      next = null;
      i = -1;
    }
    _index = i;
    _node = next;

    return i == _index ? next : null;
  }
  
  public int getLength()
  {
    if (_changeCount != _top._owner._changeCount)
      _length = -1;
    
    if (_length >= 0)
      return _length;

    QAbstractNode end = getEnd();
    _length = 0;
    for (QAbstractNode ptr = _first; ptr != end; ptr = ptr.getNextPreorder()) {
      if (_predicate.isMatch(ptr))
	_length++;
    }
      
    return _length;
  }

  /**
   * Returns the final node in the preorder.
   */
  QAbstractNode getEnd()
  {
    QAbstractNode end = _top;

    if (_first == null)
      return null;

    while (end != null && end._next == null)
      end = end._parent;

    return end == null ? null : end._next;
  }
}
