/*
    * 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.model.beans;
  
  import java.util.Locale;
  
  import org.apache.commons.jxpath.JXPathContext;
  import org.apache.commons.jxpath.ri.QName;
  import org.apache.commons.jxpath.ri.model.NodePointer;
  
  /**
   * Pointer whose value is {@code null}.
   */
  public class NullPointer extends PropertyOwnerPointer {
  
      private static final long serialVersionUID = 2193425983220679887L;
  
      /**
       * The name of this node
       */
      private final QName qName;
  
      /**
       * Optional ID, may be null.
       */
      private final String id;
  
      /**
       * Constructs a new NullPointer.
       *
       * @param locale Locale.
       * @param id     ID.
       */
      public NullPointer(final Locale locale, final String id) {
          super(null, locale);
          this.id = id;
          this.qName = null;
      }
  
      /**
       * Used for the root node.
       *
       * @param parent parent pointer
       * @param qName  node name
       */
      public NullPointer(final NodePointer parent, final QName qName) {
          super(parent);
          this.qName = qName;
          this.id = null;
      }
  
      /**
       * Constructs a new NullPointer.
       *
       * @param qName  node name
       * @param locale Locale
       */
      public NullPointer(final QName qName, final Locale locale) {
          super(null, locale);
          this.qName = qName;
          this.id = null;
      }
  
      @Override
      public String asPath() {
          if (id != null) {
              return "id(" + id + ")";
          }
          return parent == null ? "null()" : super.asPath();
      }
  
      @Override
      public NodePointer createChild(final JXPathContext context, final QName qName, final int index) {
          return createPath(context).createChild(context, qName, index);
      }
  
      @Override
      public NodePointer createChild(final JXPathContext context, final QName qName, final int index, final Object value) {
          return createPath(context).createChild(context, qName, index, value);
      }
  
      @Override
      public NodePointer createPath(final JXPathContext context) {
          if (parent != null) {
             return parent.createPath(context).getValuePointer();
         }
         throw new UnsupportedOperationException("Cannot create the root object: " + asPath());
     }
 
     @Override
     public NodePointer createPath(final JXPathContext context, final Object value) {
         if (parent != null) {
             return parent.createPath(context, value).getValuePointer();
         }
         throw new UnsupportedOperationException("Cannot create the root object: " + asPath());
     }
 
     @Override
     public boolean equals(final Object object) {
         if (object == this) {
             return true;
         }
         if (!(object instanceof NullPointer)) {
             return false;
         }
         final NullPointer other = (NullPointer) object;
         return qName == other.qName || qName != null && qName.equals(other.qName);
     }
 
     @Override
     public Object getBaseValue() {
         return null;
     }
 
     @Override
     public int getLength() {
         return 0;
     }
 
     @Override
     public QName getName() {
         return qName;
     }
 
     @Override
     public PropertyPointer getPropertyPointer() {
         return new NullPropertyPointer(this);
     }
 
     @Override
     public int hashCode() {
         return qName == null ? 0 : qName.hashCode();
     }
 
     @Override
     public boolean isActual() {
         return false;
     }
 
     @Override
     public boolean isCollection() {
         return false;
     }
 
     @Override
     public boolean isLeaf() {
         return true;
     }
 }