/*
    * Copyright (c) 2002-2026 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 java.util.AbstractSequentialList;
  import java.util.ListIterator;
  import java.util.NoSuchElementException;
  
  import org.w3c.dom.Node;
  
  /**
   * An implementation of DomNodeList that is much less expensive for iteration.
   *
   * @author Tom Anderson
   * @author Ronald Brill
   */
  class SiblingDomNodeList extends AbstractSequentialList<DomNode> implements DomNodeList<DomNode> {
  
      private final DomNode parent_;
  
      SiblingDomNodeList(final DomNode parent) {
          super();
          parent_ = parent;
      }
  
      /**
       * {@inheritDoc}
       */
      @Override
      public int getLength() {
          int length = 0;
          for (DomNode node = parent_.getFirstChild(); node != null; node = node.getNextSibling()) {
              length++;
          }
          return length;
      }
  
      /**
       * {@inheritDoc}
       */
      @Override
      public int size() {
          return getLength();
      }
  
      /**
       * {@inheritDoc}
       */
      @Override
      public Node item(final int index) {
          return get(index);
      }
  
      /**
       * {@inheritDoc}
       */
      @Override
      public DomNode get(final int index) {
          int i = 0;
          for (DomNode node = parent_.getFirstChild(); node != null; node = node.getNextSibling()) {
              if (i == index) {
                  return node;
              }
              i++;
          }
          return null;
      }
  
      /**
       * {@inheritDoc}
       */
      @Override
      public ListIterator<DomNode> listIterator(final int index) {
          return new SiblingListIterator(index);
      }
  
      /**
       * {@inheritDoc}
       */
      @Override
      public String toString() {
          return "SiblingDomNodeList[" + parent_ + "]";
      }
  
      private class SiblingListIterator implements ListIterator<DomNode> {
          private DomNode prev_;
          private DomNode next_;
         private int nextIndex_;
 
         SiblingListIterator(final int index) {
             next_ = parent_.getFirstChild();
             nextIndex_ = 0;
             for (int i = 0; i < index; i++) {
                 next();
             }
         }
 
         /**
          * {@inheritDoc}
          */
         @Override
         public boolean hasNext() {
             return next_ != null;
         }
 
         /**
          * {@inheritDoc}
          */
         @Override
         public DomNode next() {
             if (!hasNext()) {
                 throw new NoSuchElementException();
             }
             prev_ = next_;
             next_ = next_.getNextSibling();
             nextIndex_++;
             return prev_;
         }
 
         /**
          * {@inheritDoc}
          */
         @Override
         public boolean hasPrevious() {
             return prev_ != null;
         }
 
         @Override
         public DomNode previous() {
             if (!hasPrevious()) {
                 throw new NoSuchElementException();
             }
             next_ = prev_;
             prev_ = prev_.getPreviousSibling();
             nextIndex_--;
             return next_;
         }
 
         @Override
         public int nextIndex() {
             return nextIndex_;
         }
 
         @Override
         public int previousIndex() {
             return nextIndex_ - 1;
         }
 
         @Override
         public void add(final DomNode e) {
             throw new UnsupportedOperationException();
         }
 
         @Override
         public void remove() {
             throw new UnsupportedOperationException();
         }
 
         @Override
         public void set(final DomNode e) {
             throw new UnsupportedOperationException();
         }
     }
 }