/*
    *  jDTAUS Core Container Mojo
    *  Copyright (C) 2005 Christian Schulte
    *  <cs@schulte.it>
    *
    *  This library is free software; you can redistribute it and/or
    *  modify it under the terms of the GNU Lesser General Public
    *  License as published by the Free Software Foundation; either
    *  version 2.1 of the License, or any later version.
   *
   *  This library is distributed in the hope that it will be useful,
   *  but WITHOUT ANY WARRANTY; without even the implied warranty of
   *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   *  Lesser General Public License for more details.
   *
   *  You should have received a copy of the GNU Lesser General Public
   *  License along with this library; if not, write to the Free Software
   *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
   *
   */
  package org.jdtaus.core.container.mojo;
  
  import java.io.IOException;
  import java.net.URL;
  import java.net.URLClassLoader;
  import java.util.Collections;
  import java.util.Enumeration;
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.Map;
  import java.util.Set;
  
  /**
   * Classloader for providing classpath resources.
   *
   * @author <a href="mailto:cs@schulte.it">Christian Schulte</a>
   * @version $JDTAUS: ResourceLoader.java 8743 2012-10-07 03:06:20Z schulte $
   */
  final class ResourceLoader extends URLClassLoader
  {
  
      /** The classloader delegated to. */
      private ClassLoader delegate;
  
      /** Mapping of classpath locations to a list of URLs to provide. */
      private Map locations = new HashMap();
  
      /**
       * Creates a new {@code ResourceLoader} instance taking a classloader
       * classloading is delegated to.
       *
       * @param delegate the classloader to delegate classloading to.
       */
      ResourceLoader( final ClassLoader delegate )
      {
          super( new URL[]
              {
              } );
  
          this.delegate = delegate;
      }
  
      /**
       * Creates a new {@code ResourceLoader} instance taking an array of
       * classpath URLs to back the instance and a classloader classloading is
       * delegated to.
       *
       * @param classpath array of classpath URLs to back the instance.
       * @param delegate the classloader to delegate classloading to.
       */
      ResourceLoader( final URL[] classpath, final ClassLoader delegate )
      {
          super( classpath );
          this.delegate = delegate;
      }
  
      protected Class findClass( final String name ) throws ClassNotFoundException
      {
          Class thisClass = null;
  
          try
          {
              thisClass = Class.forName( name, true, this.delegate );
          }
          catch ( final ClassNotFoundException e )
          {
              thisClass = super.findClass( name );
          }
  
          return thisClass;
      }
  
      public URL findResource( final String name )
      {
          URL thisResource = null;
  
          if ( this.locations.containsKey( name ) )
          {
              final Set resources = (Set) this.locations.get( name );
             thisResource = (URL) resources.iterator().next();
         }
         else if ( ( thisResource = super.findResource( name ) ) == null )
         {
             thisResource = this.delegate.getResource( name );
         }
 
         return thisResource;
     }
 
     public Enumeration findResources( final String name ) throws IOException
     {
         Enumeration thisResources = null;
 
         if ( this.locations.containsKey( name ) )
         {
             final Set resources = (Set) this.locations.get( name );
             thisResources = Collections.enumeration( resources );
         }
         else
         {
             thisResources = super.findResources( name );
             if ( thisResources == null || !thisResources.hasMoreElements() )
             {
                 thisResources = this.delegate.getResources( name );
             }
         }
 
         return thisResources;
     }
 
     /**
      * Adds a resource to the instance.
      *
      * @param location the location of the resource to add.
      * @param resource the resource to add.
      */
     public void addResource( final String location, final URL resource )
     {
         if ( location == null )
         {
             throw new NullPointerException( "location" );
         }
         if ( resource == null )
         {
             throw new NullPointerException( "resource" );
         }
 
         Set resources = (Set) this.locations.get( location );
         if ( resources == null )
         {
             resources = new HashSet();
             this.locations.put( location, resources );
         }
 
         resources.add( resource );
     }
 
 }