package org.apache.tomcat.maven.common.run;

 /*

  * 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 org.apache.maven.plugin.logging.Log;

 import java.lang.reflect.InvocationTargetException;

 import java.lang.reflect.Method;

 import java.util.HashSet;

 import java.util.Iterator;

 import java.util.Set;

 /**

  * Registry which collects all embedded Tomcat Servers so that they will be shutdown

  * through a shutdown hook when the JVM terminates or you can ask the registry to

  * shutdown all started servers.

  *

  * @author Mark Michaelis

  * @since 1.1

  */

 public final class EmbeddedRegistry

 {

     private static EmbeddedRegistry instance;

     private Set<Object> containers = new HashSet<Object>( 1 );

     /**

      * Don't instantiate - use the instance through {@link #getInstance()}.

      */

     private EmbeddedRegistry()

     {

         // no op

     }

     /**

      * Retrieve the lazily initialized instance of the registry.

      *

      * @return singleton instance of the registry

      */

     public static EmbeddedRegistry getInstance()

     {

         if ( instance == null )

         {

             instance = new EmbeddedRegistry();

             Runtime.getRuntime().addShutdownHook( new Thread()

             {

                 @Override

                 public void run()

                 {

                     try

                     {

                         getInstance().shutdownAll( null );

                     }

                     catch ( Exception e )

                     {

                         // ignore, the exception should already have been reported

                     }

                 }

             } );

         }

         return instance;

     }

     /**

      * Adds the given container to the registry which automatically registers it for the shutdown

      * hook.

      *

      * @param container the container to register

      * @return true if it got added; false if not

      */

     public synchronized boolean register( final Object container )

     {

         return containers.add( container );

     }

     /**

      * Shuts down all registered embedded tomcats. All tomcats which successfully shut down will be

      * removed from the registry.

      *

      * @param log the log to write possible shutdown exceptions to

      * @throws Exception the first exception which occurred will be rethrown

      */

     public synchronized void shutdownAll( final Log log )

         throws Exception

     {

         Exception firstException = null;

         for ( Iterator<Object> iterator = containers.iterator(); iterator.hasNext(); )

         {

             Object embedded = iterator.next();

             try

             {

                 Method method = embedded.getClass().getMethod( "stop", null );

                 method.invoke( embedded, null );

                 iterator.remove();

             }

             catch ( NoSuchMethodException e )

             {

                 if ( firstException == null )

                 {

                     firstException = e;

                     error( log, e, "no stop method in class " + embedded.getClass().getName() );

                 }

                 else

                 {

                     error( log, e, "Error while shutting down embedded Tomcat." );

                 }

             }

             catch ( IllegalAccessException e )

             {

                 if ( firstException == null )

                 {

                     firstException = e;

                     error( log, e, "IllegalAccessException for stop method in class " + embedded.getClass().getName() );

                 }

                 else

                 {

                     error( log, e, "Error while shutting down embedded Tomcat." );

                 }

             }

             catch ( InvocationTargetException e )

             {

                 if ( firstException == null )

                 {

                     firstException = e;

                     error( log, e, "IllegalAccessException for stop method in class " + embedded.getClass().getName() );

                 }

                 else

                 {

                     error( log, e, "Error while shutting down embedded Tomcat." );

                 }

             }

         }

         if ( firstException != null )

         {

             throw firstException;

         }

     }

     /**

      * Reports the exception. If a log is given (typically when called from within a Mojo) the

      * message will be printed to the log. Otherwise it will be printed to StdErr.

      *

      * @param log     the log to write the message to; null to write to stderr

      * @param e       exception which shall be reported

      * @param message message which shall be reported

      */

     private void error( final Log log, final Exception e, final String message )

     {

         if ( log == null )

         {

             System.err.println( "ERROR: " + message );

             e.printStackTrace();

         }

         else

         {

             log.error( message, e );

         }

     }

 }