// ========================================================================
   // Copyright (c) 2004-2009 Mort Bay Consulting Pty. Ltd.
   // ------------------------------------------------------------------------
   // All rights reserved. This program and the accompanying materials
   // are made available under the terms of the Eclipse Public License v1.0
   // and Apache License v2.0 which accompanies this distribution.
   // The Eclipse Public License is available at
   // http://www.eclipse.org/legal/epl-v10.html
   // The Apache License v2.0 is available at
  // http://www.opensource.org/licenses/apache2.0.php
  // You may elect to redistribute this code under either of these licenses.
  // ========================================================================
  
  package org.eclipse.jetty.util.log;
  
  import java.lang.reflect.Method;
  import java.security.AccessController;
  import java.security.PrivilegedAction;
  
  import org.eclipse.jetty.util.Loader;
  
  /**
   * Logging.
   * This class provides a static logging interface.  If an instance of the
   * org.slf4j.Logger class is found on the classpath, the static log methods
   * are directed to a slf4j logger for "org.eclipse.log".   Otherwise the logs
   * are directed to stderr.
   * <p>
   * The "org.eclipse.jetty.util.log.class" system property can be used
   * to select a specific logging implementation.
   * <p>
   * If the system property org.eclipse.jetty.util.log.IGNORED is set,
   * then ignored exceptions are logged in detail.
   *
   * @see StdErrLog
   * @see Slf4jLog
   */
  public class Log
  {
      public final static String EXCEPTION= "EXCEPTION ";
      public final static String IGNORED= "IGNORED";
  
      public static String __logClass;
      public static boolean __ignored;
  
      static
      {
          AccessController.doPrivileged(new PrivilegedAction<Object>()
          {
              public Object run()
              {
                  __logClass = System.getProperty("org.eclipse.jetty.util.log.class", "org.eclipse.jetty.util.log.Slf4jLog");
                  __ignored = Boolean.parseBoolean(System.getProperty("org.eclipse.jetty.util.log.IGNORED", "false"));
                  return null;
              }
          });
      }
  
      private static Logger __log;
      private static boolean __initialized;
  
      public static boolean initialized()
      {
          if (__log != null)
              return true;
  
          synchronized (Log.class)
          {
              if (__initialized)
                  return __log != null;
              __initialized = true;
          }
  
          try
          {
              Class log_class = Loader.loadClass(Log.class, __logClass);
              if (__log == null || !__log.getClass().equals(log_class))
              {
                  __log = (Logger)log_class.newInstance();
                  __log.info("Logging to {} via {}", __log, log_class.getName());
              }
          }
          catch(NoClassDefFoundError e)
          {
              initStandardLogging(e);
          }
          catch(Exception e)
          {
              initStandardLogging(e);
          }
  
          return __log != null;
      }
  
      private static void initStandardLogging(Throwable e)
      {
          Class log_class;
          if(e != null && __ignored)
              e.printStackTrace();
         if (__log == null)
         {
             log_class = StdErrLog.class;
             __log = new StdErrLog();
             __log.info("Logging to {} via {}", __log, log_class.getName());
         }
     }
 
     public static void setLog(Logger log)
     {
         Log.__log = log;
     }
 
     public static Logger getLog()
     {
         initialized();
         return __log;
     }
 
 
     /**
      * Set Log to parent Logger.
      * <p>
      * If there is a different Log class available from a parent classloader,
      * call {@link #getLogger(String)} on it and construct a {@link LoggerLog} instance
      * as this Log's Logger, so that logging is delegated to the parent Log.
      * <p>
      * This should be used if a webapp is using Log, but wishes the logging to be
      * directed to the containers log.
      * <p>
      * If there is not parent Log, then this call is equivalent to<pre>
      *   Log.setLog(Log.getLogger(name));
      * </pre>
      * @param name Logger name
      */
     public static void setLogToParent(String name)
     {
         ClassLoader loader = Log.class.getClassLoader();
         if (loader.getParent()!=null)
         {
             try
             {
                 Class<?> uberlog = loader.getParent().loadClass("org.eclipse.jetty.util.log.Log");
                 Method getLogger = uberlog.getMethod("getLogger", new Class[]{String.class});
                 Object logger = getLogger.invoke(null,name);
                 setLog(new LoggerLog(logger));
             }
             catch (Exception e)
             {
                 e.printStackTrace();
             }
         }
         else
         {
             setLog(getLogger(name));
         }
     }
 
     public static void debug(Throwable th)
     {
         if (!isDebugEnabled())
             return;
         __log.debug(EXCEPTION, th);
     }
 
     public static void debug(String msg)
     {
         if (!initialized())
             return;
         __log.debug(msg);
     }
 
     public static void debug(String msg, Object arg)
     {
         if (!initialized())
             return;
         __log.debug(msg, arg);
     }
 
     public static void debug(String msg, Object arg0, Object arg1)
     {
         if (!initialized())
             return;
         __log.debug(msg, arg0, arg1);
     }
 
     /**
      * Ignore an exception unless trace is enabled.
      * This works around the problem that log4j does not support the trace level.
      * @param thrown the Throwable to ignore
      */
     public static void ignore(Throwable thrown)
     {
         if (!initialized())
             return;
         if (__ignored)
         {
             __log.warn(IGNORED, thrown);
         }
     }
 
     public static void info(String msg)
     {
         if (!initialized())
             return;
         __log.info(msg);
     }
 
     public static void info(String msg, Object arg)
     {
         if (!initialized())
             return;
         __log.info(msg, arg);
     }
 
     public static void info(String msg, Object arg0, Object arg1)
     {
         if (!initialized())
             return;
         __log.info(msg, arg0, arg1);
     }
 
     public static boolean isDebugEnabled()
     {
         if (!initialized())
             return false;
         return __log.isDebugEnabled();
     }
 
     public static void warn(String msg)
     {
         if (!initialized())
             return;
         __log.warn(msg);
     }
 
     public static void warn(String msg, Object arg)
     {
         if (!initialized())
             return;
         __log.warn(msg, arg);
     }
 
     public static void warn(String msg, Object arg0, Object arg1)
     {
         if (!initialized())
             return;
         __log.warn(msg, arg0, arg1);
     }
 
     public static void warn(String msg, Throwable th)
     {
         if (!initialized())
             return;
         __log.warn(msg, th);
     }
 
     public static void warn(Throwable th)
     {
         if (!initialized())
             return;
         __log.warn(EXCEPTION, th);
     }
 
     /**
      * Obtain a named Logger or the default Logger if null is passed.
      * @param name the Logger name
      * @return the Logger with the given name
      */
     public static Logger getLogger(String name)
     {
         if (!initialized())
             return null;
 
         return name == null ? __log : __log.getLogger(name);
     }
 }