package org.codehaus.plexus.classworlds;
   
   /*
    * Copyright 2001-2006 Codehaus Foundation.
    *
    * Licensed 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.Closeable;
  import java.io.IOException;
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.LinkedHashMap;
  import java.util.List;
  import java.util.Map;
  import java.util.function.Predicate;
  
  import org.codehaus.plexus.classworlds.realm.ClassRealm;
  import org.codehaus.plexus.classworlds.realm.DuplicateRealmException;
  import org.codehaus.plexus.classworlds.realm.FilteredClassRealm;
  import org.codehaus.plexus.classworlds.realm.NoSuchRealmException;
  
  /**
   * A collection of <code>ClassRealm</code>s, indexed by id.
   *
   * @author <a href="mailto:bob@eng.werken.com">bob mcwhirter</a>
   */
  public class ClassWorld implements Closeable {
      private Map<String, ClassRealm> realms;
  
      private final List<ClassWorldListener> listeners = new ArrayList<>();
  
      public ClassWorld(String realmId, ClassLoader classLoader) {
          this();
  
          try {
              newRealm(realmId, classLoader);
          } catch (DuplicateRealmException e) {
              // Will never happen as we are just creating the world.
          }
      }
  
      public ClassWorld() {
          this.realms = new LinkedHashMap<>();
      }
  
      public ClassRealm newRealm(String id) throws DuplicateRealmException {
          return newRealm(id, getClass().getClassLoader());
      }
  
      public ClassRealm newRealm(String id, ClassLoader classLoader) throws DuplicateRealmException {
          return newRealm(id, classLoader, null);
      }
  
      /**
       * Adds a class realm with filtering.
       * Only resources/classes whose name matches a given predicate are exposed.
       * @param id The identifier for this realm, must not be <code>null</code>.
       * @param classLoader The base class loader for this realm, may be <code>null</code> to use the bootstrap class
       *            loader.
       * @param filter a predicate to apply to each resource name to determine if it should be loaded through this class loader
       * @return the created class realm
       * @throws DuplicateRealmException in case a realm with the given id does already exist
       * @since 2.7.0
       * @see FilteredClassRealm
       */
      public synchronized ClassRealm newRealm(String id, ClassLoader classLoader, Predicate<String> filter)
              throws DuplicateRealmException {
          if (realms.containsKey(id)) {
              throw new DuplicateRealmException(this, id);
          }
  
          ClassRealm realm;
  
          if (filter == null) {
              realm = new ClassRealm(this, id, classLoader);
          } else {
              realm = new FilteredClassRealm(filter, this, id, classLoader);
          }
          realms.put(id, realm);
  
          for (ClassWorldListener listener : listeners) {
              listener.realmCreated(realm);
          }
  
          return realm;
      }
  
     /**
      * Closes all contained class realms.
      * @since 2.7.0
      */
     @Override
     public synchronized void close() throws IOException {
         realms.values().stream().forEach(this::disposeRealm);
         realms.clear();
     }
 
     public synchronized void disposeRealm(String id) throws NoSuchRealmException {
         ClassRealm realm = realms.remove(id);
 
         if (realm != null) {
             disposeRealm(realm);
         } else {
             throw new NoSuchRealmException(this, id);
         }
     }
 
     private void disposeRealm(ClassRealm realm) {
         try {
             realm.close();
         } catch (IOException ignore) {
         }
         for (ClassWorldListener listener : listeners) {
             listener.realmDisposed(realm);
         }
     }
 
     public synchronized ClassRealm getRealm(String id) throws NoSuchRealmException {
         if (realms.containsKey(id)) {
             return realms.get(id);
         }
 
         throw new NoSuchRealmException(this, id);
     }
 
     public synchronized Collection<ClassRealm> getRealms() {
         return Collections.unmodifiableList(new ArrayList<>(realms.values()));
     }
 
     // from exports branch
     public synchronized ClassRealm getClassRealm(String id) {
         if (realms.containsKey(id)) {
             return realms.get(id);
         }
 
         return null;
     }
 
     public synchronized void addListener(ClassWorldListener listener) {
         // TODO ideally, use object identity, not equals
         if (!listeners.contains(listener)) {
             listeners.add(listener);
         }
     }
 
     public synchronized void removeListener(ClassWorldListener listener) {
         listeners.remove(listener);
     }
 }