/*
    * Copyright (c) 2002-2025 Gargoyle Software Inc.
    *
    * Licensed under the Apache License, Version 2.0 (the "License");
    * you may not use this file except in compliance with the License.
    * You may obtain a copy of the License at
    * https://www.apache.org/licenses/LICENSE-2.0
    *
    * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.htmlunit.html;
  
  import org.w3c.dom.Node;
  import org.w3c.dom.traversal.NodeFilter;
  import org.w3c.dom.traversal.NodeIterator;
  
  /**
   * An implementation of {@link NodeIterator}.
   *
   * @author Ahmed Ashour
   * @author Ronald Brill
   */
  public class DomNodeIterator implements NodeIterator {
  
      private final DomNode root_;
      private final int whatToShow_;
      private final NodeFilter filter_;
      private DomNode referenceNode_;
      private final boolean expandEntityReferences_;
      private boolean pointerBeforeReferenceNode_;
  
      /**
       * Creates a new instance.
       *
       * @param root The root node at which to begin the {@link NodeIterator}'s traversal
       * @param whatToShow an optional int representing a bitmask created by combining
       *        the constant properties of {@link NodeFilter}
       * @param expandEntityReferences If false, the contents of
       *          EntityReference nodes are not present in the logical view.
       * @param filter an object implementing the {@link NodeFilter} interface
       */
      public DomNodeIterator(final DomNode root, final int whatToShow, final NodeFilter filter,
              final boolean expandEntityReferences) {
          root_ = root;
          referenceNode_ = root;
          whatToShow_ = whatToShow;
          filter_ = filter;
          expandEntityReferences_ = expandEntityReferences;
          pointerBeforeReferenceNode_ = true;
      }
  
      /**
       * {@inheritDoc}
       */
      @Override
      public DomNode getRoot() {
          return root_;
      }
  
      /**
       * {@inheritDoc}
       */
      @Override
      public int getWhatToShow() {
          return whatToShow_;
      }
  
      /**
       * {@inheritDoc}
       */
      @Override
      public boolean getExpandEntityReferences() {
          return expandEntityReferences_;
      }
  
      /**
       * {@inheritDoc}
       */
      @Override
      public NodeFilter getFilter() {
          return filter_;
      }
  
      /**
       * Returns whether the {@link NodeIterator} is anchored before, or after the node.
       * @return whether it is anchored before or after the node
       */
      public boolean isPointerBeforeReferenceNode() {
          return pointerBeforeReferenceNode_;
      }
  
      /**
       * {@inheritDoc}
       */
      @Override
     public void detach() {
         // nothing to do
     }
 
     /**
      * {@inheritDoc}
      */
     @Override
     public DomNode nextNode() {
         return traverse(true);
     }
 
     /**
      * {@inheritDoc}
      */
     @Override
     public DomNode previousNode() {
         return traverse(false);
     }
 
     private DomNode traverse(final boolean next) {
         DomNode node = referenceNode_;
         boolean beforeNode = pointerBeforeReferenceNode_;
         do {
             if (next) {
                 if (beforeNode) {
                     beforeNode = false;
                 }
                 else {
                     final DomNode leftChild = getChild(node, true);
                     if (leftChild == null) {
                         final DomNode rightSibling = getSibling(node, false);
                         if (rightSibling == null) {
                             node = getFirstUncleNode(node);
                         }
                         else {
                             node = rightSibling;
                         }
                     }
                     else {
                         node = leftChild;
                     }
                 }
             }
             else {
                 if (beforeNode) {
                     DomNode follow = getSibling(node, true);
                     if (follow != null) {
                         while (follow.hasChildNodes()) {
                             final DomNode toFollow = getChild(follow, false);
                             if (toFollow == null) {
                                 break;
                             }
                             follow = toFollow;
                         }
                     }
                     node = follow;
                 }
                 else {
                     beforeNode = true;
                 }
             }
         }
         while (node != null && (!isNodeVisible(node) || !isAccepted(node)));
 
         //apply filter here and loop
 
         referenceNode_ = node;
         pointerBeforeReferenceNode_ = beforeNode;
         return node;
     }
 
     private boolean isNodeVisible(final Node node) {
         return (whatToShow_ & HtmlDomTreeWalker.getFlagForNode(node)) != 0;
     }
 
     private boolean isAccepted(final Node node) {
         if (filter_ == null) {
             return true;
         }
         return filter_.acceptNode(node) == NodeFilter.FILTER_ACCEPT;
     }
 
     /**
      * Helper method to get the first uncle node in document order (preorder
      * traversal) from the given node.
      */
     private DomNode getFirstUncleNode(final DomNode node) {
         if (node == null || node == root_) {
             return null;
         }
 
         final DomNode parent = node.getParentNode();
         if (parent == null || parent == root_) {
             return null;
         }
 
         final DomNode uncle = getSibling(parent, false);
         if (uncle != null) {
             return uncle;
         }
 
         return getFirstUncleNode(parent);
     }
 
     private static DomNode getChild(final DomNode node, final boolean lookLeft) {
         if (node == null) {
             return null;
         }
 
         final DomNode child;
         if (lookLeft) {
             child = node.getFirstChild();
         }
         else {
             child = node.getLastChild();
         }
 
         return child;
     }
 
     private static DomNode getSibling(final DomNode node, final boolean lookLeft) {
         if (node == null) {
             return null;
         }
 
         final DomNode sibling;
         if (lookLeft) {
             sibling = node.getPreviousSibling();
         }
         else {
             sibling = node.getNextSibling();
         }
 
         return sibling;
     }
 }