/*
    * Copyright 2007 Edward Kuns
    *
    * 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
    *
    * 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.
   *
   * $Id: Element.java 0000 2007-01-11 00:00:00Z ekuns $
   */
  package org.castor.xmlctf.xmldiff.xml.nodes;
  
  import java.util.Iterator;
  import java.util.LinkedList;
  
  import org.castor.xmlctf.xmldiff.xml.Location;
  
  /**
   * A representation of an Element XML node.
   *
   * @author <a href="mailto:edward.kuns@aspect.com">Edward Kuns</a>
   * @version $Revision: 0000 $ $Date: 2007-01-11 00:00:00 -0600 (Thu, 11 Jan 2007) $
   * @since Castor 1.1
   */
  public class Element extends ParentNode {
  
    /** Serial Version UID. */
    private static final long serialVersionUID = 7995110660306473483L;
    /** Our list of Attributes. */
    private final LinkedList _attributes = new LinkedList();
    /** Our list of Namespaces. */
    private final LinkedList _namespaces = new LinkedList();
    /** Our location */
    private Location _location = null;
  
    /**
     * Creates a new Element.
     *
     * @param namespace the namespace URI for this node. (May be null.)
     * @param localName the localname of this node. (Cannot be null.)
     */
    public Element(final String namespace, final String localName) {
      super(namespace, localName, XMLNode.ELEMENT);
    }
  
    /**
     * Returns an Iterator over the List of Attributes.
     * 
     * @return an Iterator over the List of Attributes.
     */
    public Iterator getAttributeIterator() {
      return _attributes.iterator();
    }
  
    /**
     * Returns the value of the named attribute, or null if the node has no such attribute. If the
     * argument <tt>uri</tt> is null, the node's namespace URI will be used.
     *
     * @param uri The attribute's namespace URI, or null
     * @param localName The attribute's local name
     * @return The attribute's value, or null if no such attribute exists
     */
    public String getAttribute(final String uri, final String localName) {
      for (Iterator i = _attributes.iterator(); i.hasNext();) {
        Attribute attr = (Attribute) i.next();
        if (namespacesEqual(uri, attr.getNamespaceURI()) && attr.getLocalName().equals(localName)) {
          return attr.getStringValue();
        }
      }
      return null;
    }
  
    /**
     * Returns the namespace URI associated with this namespace prefix, as defined in the context of
     * this node. Returns null if the prefix is undefined. Returns an empty String if the prefix is
     * defined and associated with no namespace.
     *
     * @param prefix The namespace prefix
     * @return The namespace URI, or null.
     */
    public String getNamespaceURI(final String prefix) {
      String desiredPrefix = (prefix == null) ? "" : prefix;
  
      for (Iterator i = _namespaces.iterator(); i.hasNext();) {
        Namespace ns = (Namespace) i.next();
        if (desiredPrefix.equals(ns.getPrefix())) {
          return ns.getNamespaceUri();
        }
      }
  
      // If we didn't find it, search our parent
      return super.getNamespaceURI(desiredPrefix);
    }
  
   /**
    * Returns the namespace prefix associated with this namespace URI, as defined in the context of
    * this node. Returns null if no prefix is defined for this namespace URI. Returns an empty string
    * if the default prefix is associated with this namespace URI.
    *
    * @param uri The namespace URI
    * @return The namespace prefix, or null
    */
   public String getNamespacePrefix(final String uri) {
     String desiredUri = (uri == null) ? "" : uri;
 
     for (Iterator i = _namespaces.iterator(); i.hasNext();) {
       Namespace ns = (Namespace) i.next();
       if (desiredUri.equals(ns.getNamespaceUri())) {
         return ns.getPrefix();
       }
     }
 
     // If we didn't find it locally, search our parent
     ParentNode parent = getParentNode();
     if (parent != null && parent instanceof Element) {
       return ((Element) parent).getNamespacePrefix(desiredUri);
     }
 
     // If no parent, return null
     return null;
   }
 
   /**
    * Adds the given Attribute to this Element.
    *
    * @param attr the Attribute to add
    */
   public void addAttribute(final Attribute attr) {
     if (attr == null) {
       return;
     }
 
     attr.setParent(this);
     _attributes.add(attr);
   }
 
   /**
    * Adds the given Namespace to this Element.
    *
    * @param namespace the Namespace to add
    */
   public void addNamespace(final Namespace namespace) {
     if (namespace == null) {
       return;
     }
 
     _namespaces.add(namespace);
   }
 
   /**
    * Returns true if the given two namespace URI strings are equal.
    *
    * @param ns1 The first namespace URI to compare
    * @param ns2 The second namespace URI to compare
    * @return true if the given two namespace URI strings are equal.
    */
   private boolean namespacesEqual(final String ns1, final String ns2) {
     final String namespace1 = (ns1 == null) ? "" : ns1;
     final String namespace2 = (ns2 == null) ? "" : ns2;
 
     return namespace1.equals(namespace2);
   }
 
   /**
    * Sets the location of this Element in the document.
    * 
    * @param location the location of this Element in the document.
    */
   public void setLocation(final Location location) {
     _location = location;
   }
 
   /**
    * Returns the location of this Element in the document.
    * 
    * @return the location of this Element in the document.
    */
   public Location getLocation() {
     return _location;
   }
 
 }