/*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements.  See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF licenses this file to You 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
    *
    *     http://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.apache.commons.jxpath.ri.axes;
  
  import org.apache.commons.jxpath.ri.Compiler;
  import org.apache.commons.jxpath.ri.EvalContext;
  import org.apache.commons.jxpath.ri.QName;
  import org.apache.commons.jxpath.ri.compiler.NodeNameTest;
  import org.apache.commons.jxpath.ri.compiler.NodeTest;
  import org.apache.commons.jxpath.ri.compiler.NodeTypeTest;
  import org.apache.commons.jxpath.ri.model.NodeIterator;
  import org.apache.commons.jxpath.ri.model.NodePointer;
  
  /**
   * EvalContext that walks the "attribute::" axis.
   *
   * @author Dmitri Plotnikov
   * @version $Revision: 652845 $ $Date: 2008-05-02 19:46:46 +0200 (Fr, 02 Mai 2008) $
   */
  public class AttributeContext extends EvalContext {
      private static final QName WILDCARD = new QName(null, "*");
  
      private NodeTest nodeTest;
      private boolean setStarted = false;
      private NodeIterator iterator;
      private NodePointer currentNodePointer;
  
      /**
       * Create a new AttributeContext.
       * @param parentContext represents the previous step on the path
       * @param nodeTest is the name of the attribute we are looking for
       */
      public AttributeContext(EvalContext parentContext, NodeTest nodeTest) {
          super(parentContext);
          this.nodeTest = nodeTest;
      }
  
      public NodePointer getCurrentNodePointer() {
          return currentNodePointer;
      }
  
      public void reset() {
          setStarted = false;
          iterator = null;
          super.reset();
      }
  
      public boolean setPosition(int position) {
          if (position < getCurrentPosition()) {
              reset();
          }
  
          while (getCurrentPosition() < position) {
              if (!nextNode()) {
                  return false;
              }
          }
          return true;
      }
  
      public boolean nextNode() {
          super.setPosition(getCurrentPosition() + 1);
          if (!setStarted) {
              setStarted = true;
              QName name;
              if (nodeTest instanceof NodeNameTest) {
                  name = ((NodeNameTest) nodeTest).getNodeName();
              }
              else {
                  if (nodeTest instanceof NodeTypeTest
                          && ((NodeTypeTest) nodeTest).getNodeType() == Compiler.NODE_TYPE_NODE) {
                      name = WILDCARD;
                  }
                  else {
                      iterator = null;
                      return false;
                  }
              }
              iterator = parentContext.getCurrentNodePointer().attributeIterator(
                      name);
          }
          if (iterator == null) {
              return false;
          }
          if (!iterator.setPosition(iterator.getPosition() + 1)) {
             return false;
         }
         currentNodePointer = iterator.getNodePointer();
         return true;
     }
 }