/*
    * 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.logging.log4j.util;
  
  import java.net.URL;
  import java.security.Permission;
  import java.util.List;
  
  import org.apache.logging.log4j.Logger;
  import org.apache.logging.log4j.spi.LoggerContextFactory;
  import org.apache.logging.log4j.status.StatusLogger;
  import org.osgi.framework.AdaptPermission;
  import org.osgi.framework.AdminPermission;
  import org.osgi.framework.Bundle;
  import org.osgi.framework.BundleActivator;
  import org.osgi.framework.BundleContext;
  import org.osgi.framework.BundleEvent;
  import org.osgi.framework.SynchronousBundleListener;
  import org.osgi.framework.wiring.BundleWire;
  import org.osgi.framework.wiring.BundleWiring;
  
  /**
   * OSGi bundle activator. Used for locating an implementation of
   * {@link org.apache.logging.log4j.spi.LoggerContextFactory} et al. that have corresponding
   * {@code META-INF/log4j-provider.properties} files. As with all OSGi BundleActivator classes, this class is not for
   * public use and is only useful in an OSGi framework environment.
   */
  public class Activator implements BundleActivator, SynchronousBundleListener {
  
      private static final SecurityManager SECURITY_MANAGER = System.getSecurityManager();
  
      private static final Logger LOGGER = StatusLogger.getLogger();
  
      private static void checkPermission(final Permission permission) {
          if (SECURITY_MANAGER != null) {
              SECURITY_MANAGER.checkPermission(permission);
          }
      }
  
      private void loadProvider(final Bundle bundle) {
          if (bundle.getState() == Bundle.UNINSTALLED) {
              return;
          }
          try {
              checkPermission(new AdminPermission(bundle, AdminPermission.RESOURCE));
              checkPermission(new AdaptPermission(BundleWiring.class.getName(), bundle, AdaptPermission.ADAPT));
              loadProvider(bundle.adapt(BundleWiring.class));
          } catch (final SecurityException e) {
              LOGGER.debug("Cannot access bundle [{}] contents. Ignoring.", bundle.getSymbolicName(), e);
          } catch (final Exception e) {
              LOGGER.warn("Problem checking bundle {} for Log4j 2 provider.", bundle.getSymbolicName(), e);
          }
      }
  
      private void loadProvider(BundleWiring provider) {
          final List<URL> urls = provider.findEntries("META-INF", "log4j-provider.properties", 0);
          for (final URL url : urls) {
              ProviderUtil.loadProvider(url, provider.getClassLoader());
          }
      }
  
      @Override
      public void start(final BundleContext context) throws Exception {
          final BundleWiring self = context.getBundle().adapt(BundleWiring.class);
          final List<BundleWire> required = self.getRequiredWires(LoggerContextFactory.class.getName());
          for (BundleWire wire : required) {
              loadProvider(wire.getProviderWiring());
          }
          context.addBundleListener(this);
          final Bundle[] bundles = context.getBundles();
          for (final Bundle bundle : bundles) {
              loadProvider(bundle);
          }
      }
  
      @Override
      public void stop(final BundleContext context) throws Exception {
          context.removeBundleListener(this);
      }
  
      @Override
      public void bundleChanged(final BundleEvent event) {
          switch (event.getType()) {
              case BundleEvent.STARTED:
                  // FIXME: LogManager won't see this update if it happens after LogManager is loaded
                 loadProvider(event.getBundle());
                 break;
 
             default:
                 break;
         }
     }
 
 }