/*
    * 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.maven.plugins.shade.resource;
  
  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.LinkedHashMap;
  import java.util.List;
  import java.util.Map;
  import java.util.jar.JarEntry;
  import java.util.jar.JarOutputStream;
  
  import org.apache.maven.plugins.shade.relocation.Relocator;
  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;
  
  /**
   * A resource processor that aggregates plexus <code>components.xml</code> files.
   */
  public class ComponentsXmlResourceTransformer extends AbstractCompatibilityTransformer {
      private Map<String, Xpp3Dom> components = new LinkedHashMap<>();
  
      private long time = Long.MIN_VALUE;
  
      public static final String COMPONENTS_XML_PATH = "META-INF/plexus/components.xml";
  
      @Override
      public boolean canTransformResource(String resource) {
          return COMPONENTS_XML_PATH.equals(resource);
      }
  
      @Override
      public void processResource(String resource, InputStream is, List<Relocator> relocators, long time)
              throws IOException {
          Xpp3Dom newDom;
  
          try {
              BufferedInputStream bis = new BufferedInputStream(is) {
                  @Override
                  public void close() throws IOException {
                      // leave ZIP open
                  }
              };
  
              Reader reader = ReaderFactory.newXmlReader(bis);
  
              newDom = Xpp3DomBuilder.build(reader);
          } catch (Exception e) {
              throw new IOException("Error parsing components.xml in " + is, 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 (Xpp3Dom component : children) {
              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);
         }
 
         if (time > this.time) {
             this.time = time;
         }
     }
 
     @Override
     public void modifyOutputStream(JarOutputStream jos) throws IOException {
         JarEntry jarEntry = new JarEntry(COMPONENTS_XML_PATH);
         jarEntry.setTime(time);
 
         byte[] data = getTransformedResource();
 
         jos.putNextEntry(jarEntry);
 
         jos.write(data);
 
         components.clear();
     }
 
     @Override
     public boolean hasTransformedResource() {
         return !components.isEmpty();
     }
 
     byte[] getTransformedResource() throws IOException {
         ByteArrayOutputStream baos = new ByteArrayOutputStream(1024 * 4);
 
         try (Writer writer = WriterFactory.newXmlWriter(baos)) {
             Xpp3Dom dom = new Xpp3Dom("component-set");
 
             Xpp3Dom componentDom = new Xpp3Dom("components");
 
             dom.addChild(componentDom);
 
             for (Xpp3Dom component : components.values()) {
                 componentDom.addChild(component);
             }
 
             Xpp3DomWriter.write(writer, dom);
         }
 
         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);
     }
 }