package org.apache.maven.classrealm;
   
   /*
    * 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 java.io.File;
  import java.net.MalformedURLException;
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.LinkedHashSet;
  import java.util.List;
  import java.util.Map;
  import java.util.Objects;
  import java.util.Random;
  import java.util.Set;
  import java.util.TreeMap;
  
  import javax.inject.Inject;
  import javax.inject.Named;
  import javax.inject.Singleton;
  
  import org.apache.maven.artifact.ArtifactUtils;
  import org.apache.maven.classrealm.ClassRealmRequest.RealmType;
  import org.apache.maven.extension.internal.CoreExportsProvider;
  import org.apache.maven.model.Model;
  import org.apache.maven.model.Plugin;
  import org.codehaus.plexus.MutablePlexusContainer;
  import org.codehaus.plexus.PlexusContainer;
  import org.codehaus.plexus.classworlds.ClassWorld;
  import org.codehaus.plexus.classworlds.realm.ClassRealm;
  import org.codehaus.plexus.classworlds.realm.DuplicateRealmException;
  import org.codehaus.plexus.logging.Logger;
  import org.codehaus.plexus.util.StringUtils;
  import org.eclipse.aether.artifact.Artifact;
  
  /**
   * Manages the class realms used by Maven. <strong>Warning:</strong> This is an internal utility class that is only
   * public for technical reasons, it is not part of the public API. In particular, this class can be changed or deleted
   * without prior notice.
   *
   * @author Benjamin Bentmann
   */
  @Named
  @Singleton
  public class DefaultClassRealmManager
      implements ClassRealmManager
  {
      public static final String API_REALMID = "maven.api";
  
      /**
       * During normal command line build, ClassWorld is loaded by jvm system classloader, which only includes
       * plexus-classworlds jar and possibly javaagent classes, see https://issues.apache.org/jira/browse/MNG-4747.
       * <p>
       * Using ClassWorld to determine plugin/extensions realm parent classloaders gives m2e and integration test harness
       * flexibility to load multiple version of maven into dedicated classloaders without assuming state of jvm system
       * classloader.
       */
      private static final ClassLoader PARENT_CLASSLOADER = ClassWorld.class.getClassLoader();
  
      private final Logger logger;
  
      private final ClassWorld world;
  
      private final ClassRealm containerRealm;
  
      // this is a live injected collection
      private final List<ClassRealmManagerDelegate> delegates;
  
      private final ClassRealm mavenApiRealm;
  
      /**
       * Patterns of artifacts provided by maven core and exported via maven api realm. These artifacts are filtered from
       * plugin and build extensions realms to avoid presence of duplicate and possibly conflicting classes on classpath.
       */
      private final Set<String> providedArtifacts;
  
      @Inject
      public DefaultClassRealmManager( Logger logger, PlexusContainer container,
                                       List<ClassRealmManagerDelegate> delegates, CoreExportsProvider exports )
      {
          this.logger = logger;
          this.world = ( (MutablePlexusContainer) container ).getClassWorld();
          this.containerRealm = container.getContainerRealm();
         this.delegates = delegates;
 
         Map<String, ClassLoader> foreignImports = exports.get().getExportedPackages();
 
         this.mavenApiRealm =
             createRealm( API_REALMID, RealmType.Core, null /* parent */, null /* parentImports */,
                          foreignImports, null /* artifacts */ );
 
         this.providedArtifacts = exports.get().getExportedArtifacts();
     }
 
     private ClassRealm newRealm( String id )
     {
         synchronized ( world )
         {
             String realmId = id;
 
             Random random = new Random();
 
             while ( true )
             {
                 try
                 {
                     ClassRealm classRealm = world.newRealm( realmId, null );
 
                     if ( logger.isDebugEnabled() )
                     {
                         logger.debug( "Created new class realm " + realmId );
                     }
 
                     return classRealm;
                 }
                 catch ( DuplicateRealmException e )
                 {
                     realmId = id + '-' + random.nextInt();
                 }
             }
         }
     }
 
     public ClassRealm getMavenApiRealm()
     {
         return mavenApiRealm;
     }
 
     /**
      * Creates a new class realm with the specified parent and imports.
      *
      * @param baseRealmId The base id to use for the new realm, must not be {@code null}.
      * @param type The type of the class realm, must not be {@code null}.
      * @param parent The parent realm for the new realm, may be {@code null}.
      * @param parentImports The packages/types to import from the parent realm, may be {@code null}.
      * @param foreignImports The packages/types to import from foreign realms, may be {@code null}.
      * @param artifacts The artifacts to add to the realm, may be {@code null}. Unresolved artifacts (i.e. with a
      *            missing file) will automatically be excluded from the realm.
      * @return The created class realm, never {@code null}.
      */
     private ClassRealm createRealm( String baseRealmId, RealmType type, ClassLoader parent, List<String> parentImports,
                                     Map<String, ClassLoader> foreignImports, List<Artifact> artifacts )
     {
         Set<String> artifactIds = new LinkedHashSet<>();
 
         List<ClassRealmConstituent> constituents = new ArrayList<>();
 
         if ( artifacts != null )
         {
             for ( Artifact artifact : artifacts )
             {
                 if ( !isProvidedArtifact( artifact ) )
                 {
                     artifactIds.add( getId( artifact ) );
                     if ( artifact.getFile() != null )
                     {
                         constituents.add( new ArtifactClassRealmConstituent( artifact ) );
                     }
                 }
             }
         }
 
         if ( parentImports != null )
         {
             parentImports = new ArrayList<>( parentImports );
         }
         else
         {
             parentImports = new ArrayList<>();
         }
 
         if ( foreignImports != null )
         {
             foreignImports = new TreeMap<>( foreignImports );
         }
         else
         {
             foreignImports = new TreeMap<>();
         }
 
         ClassRealm classRealm = newRealm( baseRealmId );
 
         if ( parent != null )
         {
             classRealm.setParentClassLoader( parent );
         }
 
         callDelegates( classRealm, type, parent, parentImports, foreignImports, constituents );
 
         wireRealm( classRealm, parentImports, foreignImports );
 
         Set<String> includedIds = populateRealm( classRealm, constituents );
 
         if ( logger.isDebugEnabled() )
         {
             artifactIds.removeAll( includedIds );
 
             for ( String id : artifactIds )
             {
                 logger.debug( "  Excluded: " + id );
             }
         }
 
         return classRealm;
     }
 
     public ClassRealm getCoreRealm()
     {
         return containerRealm;
     }
 
     public ClassRealm createProjectRealm( Model model, List<Artifact> artifacts )
     {
         Objects.requireNonNull( model, "model cannot be null" );
 
         ClassLoader parent = getMavenApiRealm();
 
         return createRealm( getKey( model ), RealmType.Project, parent, null, null, artifacts );
     }
 
     private static String getKey( Model model )
     {
         return "project>" + model.getGroupId() + ":" + model.getArtifactId() + ":" + model.getVersion();
     }
 
     public ClassRealm createExtensionRealm( Plugin plugin, List<Artifact> artifacts )
     {
         Objects.requireNonNull( plugin, "plugin cannot be null" );
 
         ClassLoader parent = PARENT_CLASSLOADER;
 
         Map<String, ClassLoader> foreignImports =
             Collections.<String, ClassLoader>singletonMap( "", getMavenApiRealm() );
 
         return createRealm( getKey( plugin, true ), RealmType.Extension, parent, null, foreignImports, artifacts );
     }
 
     private boolean isProvidedArtifact( Artifact artifact )
     {
         return providedArtifacts.contains( artifact.getGroupId() + ":" + artifact.getArtifactId() );
     }
 
     public ClassRealm createPluginRealm( Plugin plugin, ClassLoader parent, List<String> parentImports,
                                          Map<String, ClassLoader> foreignImports, List<Artifact> artifacts )
     {
         Objects.requireNonNull( plugin, "plugin cannot be null" );
 
         if ( parent == null )
         {
             parent = PARENT_CLASSLOADER;
         }
 
         return createRealm( getKey( plugin, false ), RealmType.Plugin, parent, parentImports, foreignImports,
                             artifacts );
     }
 
     private static String getKey( Plugin plugin, boolean extension )
     {
         String version = ArtifactUtils.toSnapshotVersion( plugin.getVersion() );
         return ( extension ? "extension>" : "plugin>" ) + plugin.getGroupId() + ":" + plugin.getArtifactId() + ":"
             + version;
     }
 
     private static String getId( Artifact artifact )
     {
         return getId( artifact.getGroupId(), artifact.getArtifactId(), artifact.getExtension(),
                       artifact.getClassifier(), artifact.getBaseVersion() );
     }
 
     private static String getId( ClassRealmConstituent constituent )
     {
         return getId( constituent.getGroupId(), constituent.getArtifactId(), constituent.getType(),
                       constituent.getClassifier(), constituent.getVersion() );
     }
 
     private static String getId( String gid, String aid, String type, String cls, String ver )
     {
         return gid + ':' + aid + ':' + type + ( StringUtils.isNotEmpty( cls ) ? ':' + cls : "" ) + ':' + ver;
     }
 
     private void callDelegates( ClassRealm classRealm, RealmType type, ClassLoader parent, List<String> parentImports,
                                 Map<String, ClassLoader> foreignImports, List<ClassRealmConstituent> constituents )
     {
         List<ClassRealmManagerDelegate> delegates = new ArrayList<>( this.delegates );
 
         if ( !delegates.isEmpty() )
         {
             ClassRealmRequest request =
                 new DefaultClassRealmRequest( type, parent, parentImports, foreignImports, constituents );
 
             for ( ClassRealmManagerDelegate delegate : delegates )
             {
                 try
                 {
                     delegate.setupRealm( classRealm, request );
                 }
                 catch ( Exception e )
                 {
                     logger.error( delegate.getClass().getName() + " failed to setup class realm " + classRealm + ": "
                         + e.getMessage(), e );
                 }
             }
         }
     }
 
     private Set<String> populateRealm( ClassRealm classRealm, List<ClassRealmConstituent> constituents )
     {
         Set<String> includedIds = new LinkedHashSet<>();
 
         if ( logger.isDebugEnabled() )
         {
             logger.debug( "Populating class realm " + classRealm.getId() );
         }
 
         for ( ClassRealmConstituent constituent : constituents )
         {
             File file = constituent.getFile();
 
             String id = getId( constituent );
             includedIds.add( id );
 
             if ( logger.isDebugEnabled() )
             {
                 logger.debug( "  Included: " + id );
             }
 
             try
             {
                 classRealm.addURL( file.toURI().toURL() );
             }
             catch ( MalformedURLException e )
             {
                 // Not going to happen
                 logger.error( e.getMessage(), e );
             }
         }
 
         return includedIds;
     }
 
     private void wireRealm( ClassRealm classRealm, List<String> parentImports, Map<String, ClassLoader> foreignImports )
     {
         if ( foreignImports != null && !foreignImports.isEmpty() )
         {
             if ( logger.isDebugEnabled() )
             {
                 logger.debug( "Importing foreign packages into class realm " + classRealm.getId() );
             }
 
             for ( Map.Entry<String, ClassLoader> entry : foreignImports.entrySet() )
             {
                 ClassLoader importedRealm = entry.getValue();
                 String imp = entry.getKey();
 
                 if ( logger.isDebugEnabled() )
                 {
                     logger.debug( "  Imported: " + imp + " < " + getId( importedRealm ) );
                 }
 
                 classRealm.importFrom( importedRealm, imp );
             }
         }
 
         if ( parentImports != null && !parentImports.isEmpty() )
         {
             if ( logger.isDebugEnabled() )
             {
                 logger.debug( "Importing parent packages into class realm " + classRealm.getId() );
             }
 
             for ( String imp : parentImports )
             {
                 if ( logger.isDebugEnabled() )
                 {
                     logger.debug( "  Imported: " + imp + " < " + getId( classRealm.getParentClassLoader() ) );
                 }
 
                 classRealm.importFromParent( imp );
             }
         }
     }
 
     private String getId( ClassLoader classLoader )
     {
         if ( classLoader instanceof ClassRealm )
         {
             return ( (ClassRealm) classLoader ).getId();
         }
         return String.valueOf( classLoader );
     }
 
 }