/*
    * $Id: XmlDefinition.java 471754 2006-11-06 14:55:09Z husted $
    *
    * 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.struts.tiles.xmlDefinition;
  
  import java.util.Iterator;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.struts.tiles.ComponentDefinition;
  import org.apache.struts.tiles.NoSuchDefinitionException;
  
  /**
    *A definition read from an XML definitions file.
    */
  public class XmlDefinition extends ComponentDefinition
  {
    /**
     * Extends attribute value.
     */
    private String inherit;
  
      /** Commons Logging instance. */
     protected static Log log = LogFactory.getLog(XmlDefinition.class);
  
    /**
     * Used for resolving inheritance.
     */
    private boolean isVisited=false;
  
  
       /**
        * Constructor.
        */
     public XmlDefinition()
     {
     super();
     //if(debug)
       //System.out.println( "create definition" );
     }
  
    /**
     * Add an attribute to this component.
     *
     * @param attribute Attribute to add.
     */
    public void addAttribute( XmlAttribute attribute)
      {
      putAttribute( attribute.getName(), attribute.getValue() );
      }
  
    /**
     * Set extends.
     *
     * @param name Name of the extended definition.
     */
    public void setExtends(String name)
      {
      inherit = name;
      }
  
    /**
     * Get extends.
     *
     * @return Name of the extended definition.
     */
    public String getExtends()
      {
      return inherit;
      }
  
    /**
     * Get extends flag.
     *
     */
    public boolean isExtending( )
      {
      return inherit!=null;
      }
  
    /**
    * Set isVisited.
    *
    */
   public void setIsVisited( boolean isVisited )
     {
     this.isVisited = isVisited;
     }
 
     /**
      * Resolve inheritance.
      * First, resolve parent's inheritance, then set path to the parent's path.
      * Also copy attributes setted in parent, and not set in child
      * If instance doesn't extend anything, do nothing.
      * @throws NoSuchDefinitionException If an inheritance can not be solved.
      */
   public void resolveInheritance( XmlDefinitionsSet definitionsSet )
     throws NoSuchDefinitionException
     {
       // Already done, or not needed ?
     if( isVisited || !isExtending() )
       return;
 
     if(log.isDebugEnabled())
       log.debug( "Resolve definition for child name='" + getName()
               + "' extends='" + getExtends() + "'.");
 
       // Set as visited to avoid endless recurisvity.
     setIsVisited( true );
 
       // Resolve parent before itself.
     XmlDefinition parent = definitionsSet.getDefinition( getExtends() );
     if( parent == null )
       { // error
       String msg = "Error while resolving definition inheritance: child '"
                            + getName() +    "' can't find its ancestor '"
                            + getExtends() +
                            "'. Please check your description file.";
       log.error( msg );
         // to do : find better exception
       throw new NoSuchDefinitionException( msg );
       }
 
     parent.resolveInheritance( definitionsSet );
 
       // Iterate on each parent's attribute and add it if not defined in child.
     Iterator parentAttributes = parent.getAttributes().keySet().iterator();
     while( parentAttributes.hasNext() )
       {
       String name = (String)parentAttributes.next();
       if( !getAttributes().containsKey(name) )
         putAttribute( name, parent.getAttribute(name) );
       }
       // Set path and role if not setted
     if( path == null )
       setPath( parent.getPath() );
     if( role == null )
       setRole( parent.getRole() );
     if( controller==null )
       {
       setController( parent.getController());
       setControllerType( parent.getControllerType());
       }
     }
 
   /**
    * Overload this definition with passed child.
    * All attributes from child are copied to this definition. Previous
    * attributes with same name are disguarded.
    * Special attribute 'path','role' and 'extends' are overloaded if defined
    * in child.
    * @param child Child used to overload this definition.
    */
   public void overload( XmlDefinition child )
     {
     if( child.getPath() != null )
       {
       path = child.getPath();
       }
     if( child.getExtends() != null )
       {
       inherit = child.getExtends();
       }
     if( child.getRole() != null )
       {
       role = child.getRole();
       }
     if( child.getController()!=null )
       {
       controller = child.getController();
       controllerType =  child.getControllerType();
       }
       // put all child attributes in parent.
     attributes.putAll( child.getAttributes());
     }
 }