package org.apache.turbine.services.uniqueid;

 import java.nio.charset.StandardCharsets;

 /*

  * 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 java.security.MessageDigest;

 import java.util.concurrent.atomic.AtomicInteger;

 import org.apache.commons.codec.binary.Base64;

 import org.apache.logging.log4j.LogManager;

 import org.apache.logging.log4j.Logger;

 import org.apache.turbine.Turbine;

 import org.apache.turbine.services.InitializationException;

 import org.apache.turbine.services.TurbineBaseService;

 import org.apache.turbine.util.GenerateUniqueId;

 /**

  * <p> This is an implementation of {@link UniqueIdService}.

  *

  * @author <a href="mailto:Rafal.Krzewski@e-point.pl">Rafal Krzewski</a>

  * @author <a href="mailto:hps@intermeta.de">Henning P. Schmiedehausen</a>

  * @version $Id: TurbineUniqueIdService.java 1854787 2019-03-04 18:30:25Z tv $

  */

 public class TurbineUniqueIdService

         extends TurbineBaseService

         implements UniqueIdService

 {

     /** Logging */

     private static final Logger log = LogManager.getLogger(TurbineUniqueIdService.class);

     /** The identifier of this instance of turbine. */

     private static String turbineId = "UNKNOWN";

     private static String turbineURL = "UNKNOWN";

     private static AtomicInteger counter;

     /**

      * <p> Initializes the service upon first Turbine.doGet()

      * invocation.

      */

     @Override

     public void init()

             throws InitializationException

     {

         try

         {

             counter = new AtomicInteger();

             // This might be a problem if the unique Id Service runs

             // before Turbine got its first request. In this case,

             // getDefaultServerData will return just a dummy value

             // which is the same for all instances of Turbine.

             //

             // TODO This needs definitely further working.

             turbineURL = Turbine.getDefaultServerData().toString();

             MessageDigest md = MessageDigest.getInstance("MD5");

             byte [] bytesId = md.digest(turbineURL.getBytes(StandardCharsets.UTF_8));

             turbineId = new String(Base64.encodeBase64(bytesId),

                     StandardCharsets.UTF_8);

             log.info("This is Turbine instance running at: {}", turbineURL);

             log.info("The instance id is #{}", turbineId);

             setInit(true);

         }

         catch (Exception e)

         {

             throw new InitializationException(

                     "Could not initialize TurbineUniqueId Service", e);

         }

     }

     /**

      * <p> Writes a message to the log upon system shutdown.

      */

     @Override

     public void shutdown()

     {

         log.info("Turbine instance running at {} shutting down.", turbineURL);

     }

     /**

      * <p> Returns an identifier of this Turbine instance that is unique

      * both on the server and worldwide.  This identifier is computed

      * as an MD5 sum of the URL (including schema, address, port if

      * different that 80/443 respectively, context and servlet name).

      * There is an overwhelming probability that this id will be

      * different that all other Turbine instances online.

      *

      * @return A String with the instance identifier.

      */

     @Override

     public String getInstanceId()

     {

         return turbineId;

     }

     /**

      * <p> Returns an identifier that is unique within this turbine

      * instance, but does not have random-like appearance.

      *

      * @return A String with the non-random looking instance

      * identifier.

      */

     @Override

     public String getUniqueId()

     {

         int current = counter.getAndIncrement();

         String id = Integer.toString(current);

         // If you manage to get more than 100 million of ids, you'll

         // start getting ids longer than 8 characters.

         if (current < 100000000)

         {

             id = ("00000000" + id).substring(id.length());

         }

         return id;

     }

     /**

      * <p> Returns a unique identifier that looks like random data.

      *

      * @return A String with the random looking instance identifier.

      */

     @Override

     public String getPseudorandomId()

     {

         return GenerateUniqueId.getIdentifier();

     }

 }