/**

  * Copyright (c) 2014-2015, Thindeck.com

  * All rights reserved.

  *

  * Redistribution and use in source and binary forms, with or without

  * modification, are permitted provided that the following conditions

  * are met: 1) Redistributions of source code must retain the above

  * copyright notice, this list of conditions and the following

  * disclaimer. 2) Redistributions in binary form must reproduce the above

  * copyright notice, this list of conditions and the following

  * disclaimer in the documentation and/or other materials provided

  * with the distribution. 3) Neither the name of the thindeck.com nor

  * the names of its contributors may be used to endorse or promote

  * products derived from this software without specific prior written

  * permission.

  *

  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT

  * NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND

  * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL

  * THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,

  * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES

  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR

  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)

  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,

  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED

  * OF THE POSSIBILITY OF SUCH DAMAGE.

  */

 package com.thindeck.dynamo;

 import java.util.concurrent.ConcurrentHashMap;

 import java.util.concurrent.ConcurrentMap;

 import lombok.EqualsAndHashCode;

 import lombok.ToString;

 import org.apache.log4j.AppenderSkeleton;

 import org.apache.log4j.Logger;

 import org.apache.log4j.PatternLayout;

 import org.apache.log4j.spi.LoggingEvent;

 /**

  * Logs from LOG4J.

  *

  * @author Yegor Bugayenko (yegor@teamed.io)

  * @version $Id$

  */

 @ToString

 @EqualsAndHashCode(callSuper = true)

 final class Drain extends AppenderSkeleton {

     /**

      * Instance of it.

      */

     public static final Drain INSTANCE = new Drain();

     /**

      * Logs per threads.

      */

     private final transient ConcurrentMap<ThreadGroup, StringBuffer> buffers;

     /**

      * Ctor.

      */

     private Drain() {

         super();

         this.buffers = new ConcurrentHashMap<>(0);

         final Logger root = Logger.getRootLogger();

         root.addAppender(this);

         this.setLayout(new PatternLayout("%c %m\n"));

         com.jcabi.log.Logger.info(

             Drain.class, "drain configured for %s", root

         );

     }

     /**

      * Get full log for thread group and clean it.

      * @return Log

      */

     public String fetch() {

         final ThreadGroup group = Thread.currentThread().getThreadGroup();

         final StringBuffer buffer = this.buffers.remove(group);

         final String text;

         if (buffer == null) {

             text = "";

         } else {

             text = buffer.toString();

         }

         return text;

     }

     @Override

     public void close() {

         // nothing

     }

     @Override

     public boolean requiresLayout() {

         return true;

     }

     @Override

     public void append(final LoggingEvent event) {

         final ThreadGroup group = Thread.currentThread().getThreadGroup();

         this.buffers.putIfAbsent(group, new StringBuffer(0));

         this.buffers.get(group).append(this.layout.format(event));

     }

 }