/*
    * 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.core;
  
  import java.io.Serializable;
  import java.util.ArrayList;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Map;
  
  import org.apache.logging.log4j.Level;
  import org.apache.logging.log4j.Marker;
  import org.apache.logging.log4j.core.config.Configuration;
  import org.apache.logging.log4j.core.config.LoggerConfig;
  import org.apache.logging.log4j.core.config.ReliabilityStrategy;
  import org.apache.logging.log4j.core.filter.CompositeFilter;
  import org.apache.logging.log4j.message.Message;
  import org.apache.logging.log4j.message.MessageFactory;
  import org.apache.logging.log4j.message.SimpleMessage;
  import org.apache.logging.log4j.spi.AbstractLogger;
  import org.apache.logging.log4j.util.Strings;
  import org.apache.logging.log4j.util.Supplier;
  
  /**
   * The core implementation of the {@link org.apache.logging.log4j.Logger} interface. Besides providing an
   * implementation of all the Logger methods, this class also provides some convenience methods for Log4j 1.x
   * compatibility as well as access to the {@link org.apache.logging.log4j.core.Filter Filters} and
   * {@link org.apache.logging.log4j.core.Appender Appenders} associated with this Logger. Note that access to these
   * underlying objects is provided primarily for use in unit tests or bridging legacy Log4j 1.x code. Future versions
   * of this class may or may not include the various methods that are noted as not being part of the public API.
   *
   * TODO All the isEnabled methods could be pushed into a filter interface.  Not sure of the utility of having
   * isEnabled be able to examine the message pattern and parameters. (RG) Moving the isEnabled methods out of
   * Logger noticeably impacts performance. The message pattern and parameters are required so that they can be
   * used in global filters.
   */
  public class Logger extends AbstractLogger implements Supplier<LoggerConfig> {
  
      private static final long serialVersionUID = 1L;
  
      /**
       * Config should be consistent across threads.
       */
      protected volatile PrivateConfig privateConfig;
  
      // FIXME: ditto to the above
      private final LoggerContext context;
  
      /**
       * The constructor.
       * @param context The LoggerContext this Logger is associated with.
       * @param messageFactory The message factory.
       * @param name The name of the Logger.
       */
      protected Logger(final LoggerContext context, final String name, final MessageFactory messageFactory) {
          super(name, messageFactory);
          this.context = context;
          privateConfig = new PrivateConfig(context.getConfiguration(), this);
      }
  
      /**
       * This method is only used for 1.x compatibility.
       * Returns the parent of this Logger. If it doesn't already exist return a temporary Logger.
       * @return The parent Logger.
       */
      public Logger getParent() {
          final LoggerConfig lc = privateConfig.loggerConfig.getName().equals(getName()) ? privateConfig.loggerConfig.getParent() :
              privateConfig.loggerConfig;
          if (lc == null) {
              return null;
          }
          if (context.hasLogger(lc.getName())) {
              return context.getLogger(lc.getName(), getMessageFactory());
          }
          return new Logger(context, lc.getName(), this.getMessageFactory());
      }
  
      /**
       * Returns the LoggerContext this Logger is associated with.
       * @return the LoggerContext.
       */
      public LoggerContext getContext() {
          return context;
      }
  
     /**
      * This method is not exposed through the public API and is provided primarily for unit testing.
      * <p>
      * If the new level is null, this logger inherits the level from its parent.
      * </p>
      * 
      * @param level The Level to use on this Logger, may be null.
      */
     public synchronized void setLevel(final Level level) {
         if (level == getLevel()) {
             return;
         }
         Level actualLevel;
         if (level != null) {
             actualLevel = level;
         } else {
             final Logger parent = getParent();
             actualLevel = parent != null ? parent.getLevel() : privateConfig.level;
         }
         privateConfig = new PrivateConfig(privateConfig, actualLevel);
     }
     
     /*
      * (non-Javadoc)
      * @see org.apache.logging.log4j.util.Supplier#get()
      */
     public LoggerConfig get() {
         return privateConfig.loggerConfig;
     }
 
     @Override
     public void logMessage(final String fqcn, final Level level, final Marker marker, final Message message, final Throwable t) {
         final Message msg = message == null ? new SimpleMessage(Strings.EMPTY) : message;
         
         // check if we need to reconfigure
         privateConfig.config.getConfigurationMonitor().checkConfiguration();
         
         final ReliabilityStrategy strategy = privateConfig.loggerConfig.getReliabilityStrategy();
         strategy.log(this, getName(), fqcn, marker, level, msg, t);
     }
 
     @Override
     public boolean isEnabled(final Level level, final Marker marker, final String message, final Throwable t) {
         return privateConfig.filter(level, marker, message, t);
     }
 
     @Override
     public boolean isEnabled(final Level level, final Marker marker, final String message) {
         return privateConfig.filter(level, marker, message);
     }
 
     @Override
     public boolean isEnabled(final Level level, final Marker marker, final String message, final Object... params) {
         return privateConfig.filter(level, marker, message, params);
     }
 
     @Override
     public boolean isEnabled(final Level level, final Marker marker, final Object message, final Throwable t) {
         return privateConfig.filter(level, marker, message, t);
     }
 
     @Override
     public boolean isEnabled(final Level level, final Marker marker, final Message message, final Throwable t) {
         return privateConfig.filter(level, marker, message, t);
     }
 
     /**
      * This method is not exposed through the public API and is used primarily for unit testing.
      * @param appender The Appender to add to the Logger.
      */
     public void addAppender(final Appender appender) {
         privateConfig.config.addLoggerAppender(this, appender);
     }
 
     /**
      * This method is not exposed through the public API and is used primarily for unit testing.
      * @param appender The Appender to remove from the Logger.
      */
     public void removeAppender(final Appender appender) {
         privateConfig.loggerConfig.removeAppender(appender.getName());
     }
 
     /**
      * This method is not exposed through the public API and is used primarily for unit testing.
      * @return A Map containing the Appender's name as the key and the Appender as the value.
      */
     public Map<String, Appender> getAppenders() {
          return privateConfig.loggerConfig.getAppenders();
     }
 
     /**
      * This method is not exposed through the public API and is used primarily for unit testing.
      * @return An Iterator over all the Filters associated with the Logger.
      */
     // FIXME: this really ought to be an Iterable instead of an Iterator
     public Iterator<Filter> getFilters() {
         final Filter filter = privateConfig.loggerConfig.getFilter();
         if (filter == null) {
             return new ArrayList<Filter>().iterator();
         } else if (filter instanceof CompositeFilter) {
             return ((CompositeFilter) filter).iterator();
         } else {
             final List<Filter> filters = new ArrayList<>();
             filters.add(filter);
             return filters.iterator();
         }
     }
 
     /**
      * Gets the Level associated with the Logger.
      *
      * @return the Level associate with the Logger.
      */
     @Override
     public Level getLevel() {
         return privateConfig.level;
     }
 
     /**
      * This method is not exposed through the public API and is used primarily for unit testing.
      * @return The number of Filters associated with the Logger.
      */
     public int filterCount() {
         final Filter filter = privateConfig.loggerConfig.getFilter();
         if (filter == null) {
             return 0;
         } else if (filter instanceof CompositeFilter) {
             return ((CompositeFilter) filter).size();
         }
         return 1;
     }
 
     /**
      * This method is not exposed through the public API and is used primarily for unit testing.
      * @param filter The Filter to add.
      */
     public void addFilter(final Filter filter) {
         privateConfig.config.addLoggerFilter(this, filter);
     }
 
     /**
      * This method is not exposed through the public API and is present only to support the Log4j 1.2
      * compatibility bridge.
      * @return true if the associated LoggerConfig is additive, false otherwise.
      */
     public boolean isAdditive() {
         return privateConfig.loggerConfig.isAdditive();
     }
 
     /**
      * This method is not exposed through the public API and is present only to support the Log4j 1.2
      * compatibility bridge.
      * @param additive Boolean value to indicate whether the Logger is additive or not.
      */
     public void setAdditive(final boolean additive) {
         privateConfig.config.setLoggerAdditive(this, additive);
     }
 
     /**
      * Associates the Logger with a new Configuration. This method is not exposed through the
      * public API.
      *
      * There are two ways that could be used to guarantee all threads are aware of changes to
      * config. 1. synchronize this method. Accessors don't need to be synchronized as Java will
      * treat all variables within a synchronized block as volatile. 2. Declare the variable
      * volatile. Option 2 is used here as the performance cost is very low and it does a better
      * job at documenting how it is used.
      *
      * @param newConfig The new Configuration.
      */
     protected void updateConfiguration(final Configuration newConfig) {
         this.privateConfig = new PrivateConfig(newConfig, this);
     }
 
     /**
      * The binding between a Logger and its configuration.
      */
     // TODO: Should not be Serializable per EJ item 74 (2nd Ed)?
     protected class PrivateConfig implements Serializable {
         private static final long serialVersionUID = 1L;
         // config fields are public to make them visible to Logger subclasses
         public final LoggerConfig loggerConfig;
         public final Configuration config;
         private final Level level;
         private final int intLevel;
         private final Logger logger;
 
         public PrivateConfig(final Configuration config, final Logger logger) {
             this.config = config;
             this.loggerConfig = config.getLoggerConfig(getName());
             this.level = this.loggerConfig.getLevel();
             this.intLevel = this.level.intLevel();
             this.logger = logger;
         }
 
         public PrivateConfig(final PrivateConfig pc, final Level level) {
             this.config = pc.config;
             this.loggerConfig = pc.loggerConfig;
             this.level = level;
             this.intLevel = this.level.intLevel();
             this.logger = pc.logger;
         }
 
         public PrivateConfig(final PrivateConfig pc, final LoggerConfig lc) {
             this.config = pc.config;
             this.loggerConfig = lc;
             this.level = lc.getLevel();
             this.intLevel = this.level.intLevel();
             this.logger = pc.logger;
         }
 
         // LOG4J2-151: changed visibility to public
         public void logEvent(final LogEvent event) {
             config.getConfigurationMonitor().checkConfiguration();
             loggerConfig.log(event);
         }
 
         boolean filter(final Level level, final Marker marker, final String msg) {
             config.getConfigurationMonitor().checkConfiguration();
             final Filter filter = config.getFilter();
             if (filter != null) {
                 final Filter.Result r = filter.filter(logger, level, marker, msg);
                 if (r != Filter.Result.NEUTRAL) {
                     return r == Filter.Result.ACCEPT;
                 }
             }
             return level != null && intLevel >= level.intLevel();
         }
 
         boolean filter(final Level level, final Marker marker, final String msg, final Throwable t) {
             config.getConfigurationMonitor().checkConfiguration();
             final Filter filter = config.getFilter();
             if (filter != null) {
                 final Filter.Result r = filter.filter(logger, level, marker, msg, t);
                 if (r != Filter.Result.NEUTRAL) {
                     return r == Filter.Result.ACCEPT;
                 }
             }
             return level != null && intLevel >= level.intLevel();
         }
 
         boolean filter(final Level level, final Marker marker, final String msg, final Object... p1) {
             config.getConfigurationMonitor().checkConfiguration();
             final Filter filter = config.getFilter();
             if (filter != null) {
                 final Filter.Result r = filter.filter(logger, level, marker, msg, p1);
                 if (r != Filter.Result.NEUTRAL) {
                     return r == Filter.Result.ACCEPT;
                 }
             }
             return level != null && intLevel >= level.intLevel();
         }
 
         boolean filter(final Level level, final Marker marker, final Object msg, final Throwable t) {
             config.getConfigurationMonitor().checkConfiguration();
             final Filter filter = config.getFilter();
             if (filter != null) {
                 final Filter.Result r = filter.filter(logger, level, marker, msg, t);
                 if (r != Filter.Result.NEUTRAL) {
                     return r == Filter.Result.ACCEPT;
                 }
             }
             return level != null && intLevel >= level.intLevel();
         }
 
         boolean filter(final Level level, final Marker marker, final Message msg, final Throwable t) {
             config.getConfigurationMonitor().checkConfiguration();
             final Filter filter = config.getFilter();
             if (filter != null) {
                 final Filter.Result r = filter.filter(logger, level, marker, msg, t);
                 if (r != Filter.Result.NEUTRAL) {
                     return r == Filter.Result.ACCEPT;
                 }
             }
             return level != null && intLevel >= level.intLevel();
         }
     }
 
     /**
      * Returns a String representation of this instance in the form {@code "name:level[ in context_name]"}.
      * @return A String describing this Logger instance.
      */
     @Override
     public String toString() {
         final String nameLevel = Strings.EMPTY + getName() + ':' + getLevel();
         if (context == null) {
             return nameLevel;
         }
         final String contextName = context.getName();
         return contextName == null ? nameLevel : nameLevel + " in " + contextName;
     }
 }