/*
    * 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.jcl;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogConfigurationException;
  import org.apache.commons.logging.LogFactory;
  import org.apache.logging.log4j.LogManager;
  import org.apache.logging.log4j.spi.AbstractLogger;
  import org.apache.logging.log4j.spi.LoggerContext;
  
  import java.util.Map;
  import java.util.WeakHashMap;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.concurrent.ConcurrentMap;
  
  /**
   *
   */
  public class LogFactoryImpl extends LogFactory {
  
      private final Map<LoggerContext, ConcurrentMap<String, Log>> contextMap =
          new WeakHashMap<LoggerContext, ConcurrentMap<String, Log>>();
  
      private final ConcurrentMap<String, Object> attributes = new ConcurrentHashMap<String, Object>();
  
      @Override
      public Log getInstance(final String name) throws LogConfigurationException {
          final LoggerContext context = PrivateManager.getContext();
          final ConcurrentMap<String, Log> loggers = getLoggersMap();
          if (loggers.containsKey(name)) {
              return loggers.get(name);
          }
          final org.apache.logging.log4j.Logger logger = PrivateManager.getLogger(name);
          if (logger instanceof AbstractLogger) {
              loggers.putIfAbsent(name, new Log4JLog((AbstractLogger) logger, name));
              return loggers.get(name);
          }
          throw new LogConfigurationException(
              "Commons Logging Adapter requires base logging system to extend Log4J AbstractLogger");
      }
  
      private ConcurrentMap<String, Log> getLoggersMap() {
          final LoggerContext context = PrivateManager.getContext();
          synchronized (contextMap) {
              ConcurrentMap<String, Log> map = contextMap.get(context);
              if (map == null) {
                  map = new ConcurrentHashMap<String, Log>();
                  contextMap.put(context, map);
              }
              return map;
          }
      }
  
      @Override
      public Object getAttribute(final String name) {
          return attributes.get(name);
      }
  
      @Override
      public String[] getAttributeNames() {
          return attributes.keySet().toArray(new String[attributes.size()]);
      }
  
      @Override
      public Log getInstance(final Class clazz) throws LogConfigurationException {
          return getInstance(clazz.getName());
      }
  
      /**
       * This method is supposed to clear all loggers. In this implementation it will clear all the logger
       * wrappers but the loggers managed by the underlying logger context will not be.
       */
      @Override
      public void release() {
          getLoggersMap().clear();
      }
  
      @Override
      public void removeAttribute(final String name) {
          attributes.remove(name);
      }
  
      @Override
      public void setAttribute(final String name, final Object value) {
         if (value != null) {
             attributes.put(name, value);
         } else {
             removeAttribute(name);
         }
     }
 
     /**
      * The real bridge between commons logging and Log4j.
      */
     private static class PrivateManager extends LogManager {
         private static final String FQCN = LogFactory.class.getName();
 
         public static LoggerContext getContext() {
             return getContext(FQCN, false);
         }
 
         public static org.apache.logging.log4j.Logger getLogger(final String name) {
             return getLogger(FQCN, name);
         }
     }
 
 }