/*
 * DomNodeIterator.java
 * Copyright (C) 2004 The Free Software Foundation
 * 
 * This file is part of GNU JAXP, a library.
 * 
 * GNU JAXP 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.
 * 
 * GNU JAXP 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.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * Linking this library statically or dynamically with other modules is
 * making a combined work based on this library.  Thus, the terms and
 * conditions of the GNU General Public License cover the whole
 * combination.
 *
 * As a special exception, the copyright holders of this library give you
 * permission to link this library with independent modules to produce an
 * executable, regardless of the license terms of these independent
 * modules, and to copy and distribute the resulting executable under
 * terms of your choice, provided that you also meet, for each linked
 * independent module, the terms and conditions of the license of that
 * module.  An independent module is a module which is not derived from
 * or based on this library.  If you modify this library, you may extend
 * this exception to your version of the library, but you are not
 * obliged to do so.  If you do not wish to do so, delete this
 * exception statement from your version.
 */
package gnu.xml.dom;

import org.w3c.dom.DOMException;
import org.w3c.dom.Node;
import org.w3c.dom.traversal.NodeFilter;
import org.w3c.dom.traversal.NodeIterator;
import org.w3c.dom.traversal.TreeWalker;

/**
 * Node iterator and tree walker.
 *
 * @author <a href='mailto:dog@gnu.org'>Chris Burdess</a>
 */
public class DomNodeIterator
  implements NodeIterator, TreeWalker
{

  Node root;
  final int whatToShow;
  final NodeFilter filter;
  final boolean entityReferenceExpansion;
  final boolean walk;
  Node current;

  public DomNodeIterator(Node root, int whatToShow, NodeFilter filter,
                         boolean entityReferenceExpansion, boolean walk)
  {
    if (root == null)
      {
        throw new DomEx(DOMException.NOT_SUPPORTED_ERR);
      }
    this.root = root;
    this.whatToShow = whatToShow;
    this.filter = filter;
    this.entityReferenceExpansion = entityReferenceExpansion;
    this.walk = walk;
    current = root;
  }

  public Node getRoot()
  {
    return root;
  }

  public int getWhatToShow()
  {
    return whatToShow;
  }

  public NodeFilter getFilter()
  {
    return filter;
  }

  public boolean getExpandEntityReferences()
  {
    return entityReferenceExpansion;
  }

  public Node nextNode()
    throws DOMException
  {
    if (root == null)
      {
        throw new DomEx(DOMException.INVALID_STATE_ERR);
      }
    Node ret;
    do
      {
        if (current.equals(root))
          {
            ret = root.getFirstChild();
          }
        else if (walk)
          {
            ret = current.getFirstChild();
            if (ret == null)
              {
                ret = current.getNextSibling();
              }
            if (ret == null)
              {
                Node tmp = current;
                ret = tmp.getParentNode();
                while (!ret.equals(root) && tmp.equals(ret.getLastChild()))
                  {
                    tmp = ret;
                    ret = tmp.getParentNode();
                  }
                if (ret.equals(root))
                  {
                    ret = null;
                  }
                else
                  {
                    ret = ret.getNextSibling();
                  }
              }
          }
        else
          {
            ret = current.getNextSibling();
          }
      }
    while (!accept(ret));
    current = (ret == null) ? current : ret;
    return ret;
  }

  public Node previousNode()
    throws DOMException
  {
    if (root == null)
      {
        throw new DomEx(DOMException.INVALID_STATE_ERR);
      }
    Node ret;
    do
      {
        if (current.equals(root))
          {
            ret = current.getLastChild();
          }
        else if (walk)
          {
            ret = current.getLastChild();
            if (ret == null)
              {
                ret = current.getPreviousSibling();
              }
            if (ret == null)
              {
                Node tmp = current;
                ret = tmp.getParentNode();
                while (!ret.equals(root) && tmp.equals(ret.getFirstChild()))
                  {
                    tmp = ret;
                    ret = tmp.getParentNode();
                  }
                if (ret.equals(root))
                  {
                    ret = null;
                  }
                else
                  {
                    ret = ret.getPreviousSibling();
                  }
              }
          }
        else
          {
            ret = current.getPreviousSibling();
          }
      }
    while (!accept(ret));
    current = (ret == null) ? current : ret;
    return ret;
  }

  public Node getCurrentNode()
  {
    return current;
  }

  public void setCurrentNode(Node current)
    throws DOMException
  {
    if (current == null)
      {
        throw new DomEx(DOMException.NOT_SUPPORTED_ERR);
      }
    this.current = current;
  }

  public Node parentNode()
  {
    Node ret = current.getParentNode();
    if (!accept (ret))
      {
        ret = null;
      }
    current = (ret == null) ? current : ret;
    return ret;
  }

  public Node firstChild ()
  {
    Node ret = current.getFirstChild();
    while (!accept(ret))
      {
        ret = ret.getNextSibling();
      }
    current = (ret == null) ? current : ret;
    return ret;
  }

  public Node lastChild()
  {
    Node ret = current.getLastChild();
    while (!accept(ret))
      {
        ret = ret.getPreviousSibling();
      }
    current = (ret == null) ? current : ret;
    return ret;
  }

  public Node previousSibling()
  {
    Node ret = current.getPreviousSibling();
    while (!accept(ret))
      {
        ret = ret.getPreviousSibling();
      }
    current = (ret == null) ? current : ret;
    return ret;
  }

  public Node nextSibling()
  {
    Node ret = current.getNextSibling();
    while (!accept(ret))
      {
        ret = ret.getNextSibling();
      }
    current = (ret == null) ? current : ret;
    return ret;
  }

  public void detach()
  {
    root = null;
  }

  boolean accept(Node node)
  {
    if (node == null)
      {
        return true;
      }
    boolean ret;
    switch (node.getNodeType())
      {
      case Node.ATTRIBUTE_NODE:
        ret = (whatToShow & NodeFilter.SHOW_ATTRIBUTE) != 0;
        break;
      case Node.CDATA_SECTION_NODE:
        ret = (whatToShow & NodeFilter.SHOW_CDATA_SECTION) != 0;
        break;
      case Node.COMMENT_NODE:
        ret = (whatToShow & NodeFilter.SHOW_COMMENT) != 0;
        break;
      case Node.DOCUMENT_NODE:
        ret = (whatToShow & NodeFilter.SHOW_DOCUMENT) != 0;
        break;
      case Node.DOCUMENT_FRAGMENT_NODE:
        ret = (whatToShow & NodeFilter.SHOW_DOCUMENT_FRAGMENT) != 0;
        break;
      case Node.DOCUMENT_TYPE_NODE:
        ret = (whatToShow & NodeFilter.SHOW_DOCUMENT_TYPE) != 0;
        break;
      case Node.ELEMENT_NODE:
        ret = (whatToShow & NodeFilter.SHOW_ELEMENT) != 0;
        break;
      case Node.ENTITY_NODE:
        ret = (whatToShow & NodeFilter.SHOW_ENTITY) != 0;
        break;
      case Node.ENTITY_REFERENCE_NODE:
        ret = (whatToShow & NodeFilter.SHOW_ENTITY_REFERENCE) != 0;
        ret = ret && entityReferenceExpansion;
        break;
      case Node.NOTATION_NODE:
        ret = (whatToShow & NodeFilter.SHOW_NOTATION) != 0;
        break;
      case Node.PROCESSING_INSTRUCTION_NODE:
        ret = (whatToShow & NodeFilter.SHOW_PROCESSING_INSTRUCTION) != 0;
        break;
      case Node.TEXT_NODE:
        ret = (whatToShow & NodeFilter.SHOW_TEXT) != 0;
        break;
      default:
        ret = true;
      }
    if (ret && filter != null)
      {
        ret = (filter.acceptNode(node) == NodeFilter.FILTER_ACCEPT);
      }
    return ret;
  }

}
