//
   //  ========================================================================
   //  Copyright (c) 1995-2014 Mort Bay Consulting Pty. Ltd.
   //  ------------------------------------------------------------------------
   //  All rights reserved. This program and the accompanying materials
   //  are made available under the terms of the Eclipse Public License v1.0
   //  and Apache License v2.0 which accompanies this distribution.
   //
   //      The Eclipse Public License is available at
  //      http://www.eclipse.org/legal/epl-v10.html
  //
  //      The Apache License v2.0 is available at
  //      http://www.opensource.org/licenses/apache2.0.php
  //
  //  You may elect to redistribute this code under either of these licenses.
  //  ========================================================================
  //
  
  package org.eclipse.jetty.websocket.api.extensions;
  
  import java.util.HashMap;
  import java.util.Iterator;
  import java.util.Map;
  import java.util.ServiceLoader;
  import java.util.Set;
  
  public abstract class ExtensionFactory implements Iterable<Class<? extends Extension>>
  {
      private ServiceLoader<Extension> extensionLoader = ServiceLoader.load(Extension.class);
      private Map<String, Class<? extends Extension>> availableExtensions;
  
      public ExtensionFactory()
      {
          availableExtensions = new HashMap<>();
          for (Extension ext : extensionLoader)
          {
              if (ext != null)
              {
                  availableExtensions.put(ext.getName(),ext.getClass());
              }
          }
      }
  
      public Map<String, Class<? extends Extension>> getAvailableExtensions()
      {
          return availableExtensions;
      }
  
      public Class<? extends Extension> getExtension(String name)
      {
          return availableExtensions.get(name);
      }
  
      public Set<String> getExtensionNames()
      {
          return availableExtensions.keySet();
      }
  
      public boolean isAvailable(String name)
      {
          return availableExtensions.containsKey(name);
      }
  
      @Override
      public Iterator<Class<? extends Extension>> iterator()
      {
          return availableExtensions.values().iterator();
      }
  
      public abstract Extension newInstance(ExtensionConfig config);
  
      public void register(String name, Class<? extends Extension> extension)
      {
          availableExtensions.put(name,extension);
      }
  
      public void unregister(String name)
      {
          availableExtensions.remove(name);
      }
  }