package org.apache.maven.plugins.shade.resource;
   
   /*
    * 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.
   */
  
  import org.apache.maven.plugins.shade.relocation.Relocator;
  import org.codehaus.plexus.util.IOUtil;
  import org.codehaus.plexus.util.ReaderFactory;
  import org.codehaus.plexus.util.WriterFactory;
  import org.codehaus.plexus.util.xml.Xpp3Dom;
  import org.codehaus.plexus.util.xml.Xpp3DomBuilder;
  import org.codehaus.plexus.util.xml.Xpp3DomWriter;
  
  import java.io.BufferedInputStream;
  import java.io.ByteArrayOutputStream;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.Reader;
  import java.io.Writer;
  import java.util.Iterator;
  import java.util.LinkedHashMap;
  import java.util.List;
  import java.util.Map;
  import java.util.jar.JarEntry;
  import java.util.jar.JarOutputStream;
  
  /**
   * A resource processor that aggregates plexus <code>components.xml</code> files.
   */
  public class ComponentsXmlResourceTransformer
      implements ResourceTransformer
  {
      private Map<String, Xpp3Dom> components = new LinkedHashMap<String, Xpp3Dom>();
  
      public static final String COMPONENTS_XML_PATH = "META-INF/plexus/components.xml";
  
      public boolean canTransformResource( String resource )
      {
          return COMPONENTS_XML_PATH.equals( resource );
      }
  
      public void processResource( String resource, InputStream is, List<Relocator> relocators )
          throws IOException
      {
          Xpp3Dom newDom;
  
          try
          {
              BufferedInputStream bis = new BufferedInputStream( is )
              {
                  public void close()
                      throws IOException
                  {
                      // leave ZIP open
                  }
              };
  
              Reader reader = ReaderFactory.newXmlReader( bis );
  
              newDom = Xpp3DomBuilder.build( reader );
          }
          catch ( Exception e )
          {
              throw (IOException) new IOException( "Error parsing components.xml in " + is ).initCause( e );
          }
  
          // Only try to merge in components if there are some elements in the component-set
          if ( newDom.getChild( "components" ) == null )
          {
              return;
          }
  
          Xpp3Dom[] children = newDom.getChild( "components" ).getChildren( "component" );
  
          for ( int i = 0; i < children.length; i++ )
          {
              Xpp3Dom component = children[i];
  
              String role = getValue( component, "role" );
              role = getRelocatedClass( role, relocators );
              setValue( component, "role", role );
  
              String roleHint = getValue( component, "role-hint" );
 
             String impl = getValue( component, "implementation" );
             impl = getRelocatedClass( impl, relocators );
             setValue( component, "implementation", impl );
 
             String key = role + ':' + roleHint;
             if ( components.containsKey( key ) )
             {
                 // TODO: use the tools in Plexus to merge these properly. For now, I just need an all-or-nothing
                 // configuration carry over
 
                 Xpp3Dom dom = components.get( key );
                 if ( dom.getChild( "configuration" ) != null )
                 {
                     component.addChild( dom.getChild( "configuration" ) );
                 }
             }
 
             Xpp3Dom requirements = component.getChild( "requirements" );
             if ( requirements != null && requirements.getChildCount() > 0 )
             {
                 for ( int r = requirements.getChildCount() - 1; r >= 0; r-- )
                 {
                     Xpp3Dom requirement = requirements.getChild( r );
 
                     String requiredRole = getValue( requirement, "role" );
                     requiredRole = getRelocatedClass( requiredRole, relocators );
                     setValue( requirement, "role", requiredRole );
                 }
             }
 
             components.put( key, component );
         }
     }
 
     public void modifyOutputStream( JarOutputStream jos )
         throws IOException
     {
         byte[] data = getTransformedResource();
 
         jos.putNextEntry( new JarEntry( COMPONENTS_XML_PATH ) );
 
         IOUtil.copy( data, jos );
 
         components.clear();
     }
 
     public boolean hasTransformedResource()
     {
         return !components.isEmpty();
     }
 
     byte[] getTransformedResource()
         throws IOException
     {
         ByteArrayOutputStream baos = new ByteArrayOutputStream( 1024 * 4 );
 
         Writer writer = WriterFactory.newXmlWriter( baos );
         try
         {
             Xpp3Dom dom = new Xpp3Dom( "component-set" );
 
             Xpp3Dom componentDom = new Xpp3Dom( "components" );
 
             dom.addChild( componentDom );
 
             for ( Iterator i = components.values().iterator(); i.hasNext(); )
             {
                 Xpp3Dom component = (Xpp3Dom) i.next();
                 componentDom.addChild( component );
             }
 
             Xpp3DomWriter.write( writer, dom );
         }
         finally
         {
             IOUtil.close( writer );
         }
 
         return baos.toByteArray();
     }
 
     private String getRelocatedClass( String className, List<Relocator> relocators )
     {
         if ( className != null && className.length() > 0 && relocators != null )
         {
             for ( Relocator relocator : relocators )
             {
                 if ( relocator.canRelocateClass( className ) )
                 {
                     return relocator.relocateClass( className );
                 }
             }
         }
 
         return className;
     }
 
     private static String getValue( Xpp3Dom dom, String element )
     {
         Xpp3Dom child = dom.getChild( element );
 
         return ( child != null && child.getValue() != null ) ? child.getValue() : "";
     }
 
     private static void setValue( Xpp3Dom dom, String element, String value )
     {
         Xpp3Dom child = dom.getChild( element );
 
         if ( child == null || value == null || value.length() <= 0 )
         {
             return;
         }
 
         child.setValue( value );
     }
 
 }