/*
    * 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.configuration2.tree.xpath;
  
  import java.util.Locale;
  
  import org.apache.commons.configuration2.tree.NodeHandler;
  import org.apache.commons.jxpath.ri.Compiler;
  import org.apache.commons.jxpath.ri.QName;
  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;
  
  /**
   * <p>
   * A specific {@code NodePointer} implementation for configuration nodes.
   * </p>
   * <p>
   * This is needed for queries using JXPath.
   * </p>
   *
   * @since 1.3
   * @param <T> the type of the nodes this pointer deals with
   */
  final class ConfigurationNodePointer<T> extends NodePointer {
      /**
       * The serial version UID.
       */
      private static final long serialVersionUID = -1087475639680007713L;
  
      /** The node handler. */
      private final NodeHandler<T> handler;
  
      /** Stores the associated node. */
      private final T node;
  
      /**
       * Creates a new instance of {@code ConfigurationNodePointer} pointing to the specified node.
       *
       * @param node the wrapped node
       * @param locale the locale
       * @param handler the {@code NodeHandler}
       */
      public ConfigurationNodePointer(final T node, final Locale locale, final NodeHandler<T> handler) {
          super(null, locale);
          this.node = node;
          this.handler = handler;
      }
  
      /**
       * Creates a new instance of {@code ConfigurationNodePointer} and initializes it with its parent pointer.
       *
       * @param parent the parent pointer
       * @param node the associated node
       * @param handler the {@code NodeHandler}
       */
      public ConfigurationNodePointer(final ConfigurationNodePointer<T> parent, final T node, final NodeHandler<T> handler) {
          super(parent);
          this.node = node;
          this.handler = handler;
      }
  
      /**
       * Returns a flag whether this node is a leaf. This is the case if there are no child nodes.
       *
       * @return a flag if this node is a leaf
       */
      @Override
      public boolean isLeaf() {
          return getNodeHandler().getChildrenCount(node, null) < 1;
      }
  
      /**
       * Returns a flag if this node is a collection. This is not the case.
       *
       * @return the collection flag
       */
      @Override
      public boolean isCollection() {
          return false;
      }
  
      /**
       * Gets this node's length. This is always 1.
      *
      * @return the node's length
      */
     @Override
     public int getLength() {
         return 1;
     }
 
     /**
      * Checks whether this node pointer refers to an attribute node. This is not the case.
      *
      * @return the attribute flag
      */
     @Override
     public boolean isAttribute() {
         return false;
     }
 
     /**
      * Gets this node's name.
      *
      * @return the name
      */
     @Override
     public QName getName() {
         return new QName(null, getNodeHandler().nodeName(node));
     }
 
     /**
      * Gets this node's base value. This is the associated configuration node.
      *
      * @return the base value
      */
     @Override
     public Object getBaseValue() {
         return node;
     }
 
     /**
      * Gets the immediate node. This is the associated configuration node.
      *
      * @return the immediate node
      */
     @Override
     public Object getImmediateNode() {
         return node;
     }
 
     /**
      * Gets the value of this node.
      *
      * @return the represented node's value
      */
     @Override
     public Object getValue() {
         return getNodeHandler().getValue(node);
     }
 
     /**
      * Sets the value of this node. This is not supported, so always an exception is thrown.
      *
      * @param value the new value
      */
     @Override
     public void setValue(final Object value) {
         throw new UnsupportedOperationException("Node value cannot be set!");
     }
 
     /**
      * Compares two child node pointers.
      *
      * @param pointer1 one pointer
      * @param pointer2 another pointer
      * @return a flag, which pointer should be sorted first
      */
     @Override
     public int compareChildNodePointers(final NodePointer pointer1, final NodePointer pointer2) {
         final Object node1 = pointer1.getBaseValue();
         final Object node2 = pointer2.getBaseValue();
 
         // sort based on the occurrence in the sub node list
         for (final T child : getNodeHandler().getChildren(node)) {
             if (child == node1) {
                 return -1;
             }
             if (child == node2) {
                 return 1;
             }
         }
         return 0; // should not happen
     }
 
     /**
      * Returns an iterator for the attributes that match the given name.
      *
      * @param name the attribute name
      * @return the iterator for the attributes
      */
     @Override
     public NodeIterator attributeIterator(final QName name) {
         return new ConfigurationNodeIteratorAttribute<>(this, name);
     }
 
     /**
      * Returns an iterator for the children of this pointer that match the given test object.
      *
      * @param test the test object
      * @param reverse the reverse flag
      * @param startWith the start value of the iteration
      */
     @Override
     public NodeIterator childIterator(final NodeTest test, final boolean reverse, final NodePointer startWith) {
         return new ConfigurationNodeIteratorChildren<>(this, test, reverse, castPointer(startWith));
     }
 
     /**
      * Tests if this node matches the given test. Configuration nodes are text nodes, too because they can contain a value.
      *
      * @param test the test object
      * @return a flag if this node corresponds to the test
      */
     @Override
     public boolean testNode(final NodeTest test) {
         if (test instanceof NodeTypeTest && ((NodeTypeTest) test).getNodeType() == Compiler.NODE_TYPE_TEXT) {
             return true;
         }
         return super.testNode(test);
     }
 
     /**
      * Gets the {@code NodeHandler} used by this instance.
      *
      * @return the {@code NodeHandler}
      */
     public NodeHandler<T> getNodeHandler() {
         return handler;
     }
 
     /**
      * Gets the wrapped configuration node.
      *
      * @return the wrapped node
      */
     public T getConfigurationNode() {
         return node;
     }
 
     /**
      * Casts the given child pointer to a node pointer of this type. This is a bit dangerous. However, in a typical setup,
      * child node pointers can only be created by this instance which ensures that they are of the correct type. Therefore,
      * this cast is safe.
      *
      * @param p the {@code NodePointer} to cast
      * @return the resulting {@code ConfigurationNodePointer}
      */
     private ConfigurationNodePointer<T> castPointer(final NodePointer p) {
         @SuppressWarnings("unchecked") // see method comment
         final ConfigurationNodePointer<T> result = (ConfigurationNodePointer<T>) p;
         return result;
     }
 }