/*
    * Copyright 2012 The Netty Project
    *
    * The Netty Project 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.jboss.netty.logging;
  
  import org.osgi.framework.BundleContext;
  import org.osgi.framework.ServiceReference;
  import org.osgi.service.log.LogService;
  import org.osgi.util.tracker.ServiceTracker;
  
  /**
   * Logger factory which creates an <a href="http://www.osgi.org/">OSGi</a>
   * {@link LogService} logger.
   */
  public class OsgiLoggerFactory extends InternalLoggerFactory {
  
      private final ServiceTracker logServiceTracker;
      private final InternalLoggerFactory fallback;
      volatile LogService logService;
  
      public OsgiLoggerFactory(BundleContext ctx) {
          this(ctx, null);
      }
  
      public OsgiLoggerFactory(BundleContext ctx, InternalLoggerFactory fallback) {
          if (ctx == null) {
              throw new NullPointerException("ctx");
          }
          if (fallback == null) {
              fallback = InternalLoggerFactory.getDefaultFactory();
              if (fallback instanceof OsgiLoggerFactory) {
                  fallback = new JdkLoggerFactory();
              }
          }
  
          this.fallback = fallback;
          logServiceTracker = new ServiceTracker(
                  ctx, "org.osgi.service.log.LogService", null) {
                      @Override
                      public Object addingService(ServiceReference reference) {
                          LogService service = (LogService) super.addingService(reference);
                          logService = service;
                          return service;
                      }
  
                      @Override
                      public void removedService(ServiceReference reference,
                              Object service) {
                          logService = null;
                      }
          };
          logServiceTracker.open();
      }
  
      public InternalLoggerFactory getFallback() {
          return fallback;
      }
  
      public LogService getLogService() {
          return logService;
      }
  
      public void destroy() {
          logService = null;
          logServiceTracker.close();
      }
  
      @Override
      public InternalLogger newInstance(String name) {
          return new OsgiLogger(this, name, fallback.newInstance(name));
      }
  }