/*
 * Copyright 2003 Federal Chancellery Austria
 * MOA-ID has been developed in a cooperation between BRZ, the Federal
 * Chancellery Austria - ICT staff unit, and Graz University of Technology.
 *
 * Licensed under the EUPL, Version 1.1 or - as soon they will be approved by
 * the European Commission - subsequent versions of the EUPL (the "Licence");
 * You may not use this work except in compliance with the Licence.
 * You may obtain a copy of the Licence at:
 * http://www.osor.eu/eupl/
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the Licence is distributed on an "AS IS" basis,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the Licence for the specific language governing permissions and
 * limitations under the Licence.
 *
 * This product combines work with different licenses. See the "NOTICE" text
 * file for details on the various modules and licenses.
 * The "NOTICE" text file is part of the distribution. Any derivative works
 * that you distribute must include a readable copy of the "NOTICE" text file.
 */


package at.gv.egovernment.moa.logging;

import java.util.HashMap;
import java.util.Map;

/**
 * A utility class acting as a facade to the logging subsystem.
 * 
 * Configure the logging defaultHierarchy that the <code>Logger</code> uses by
 * calling <code>setHierarchy</code> once before calling any of the logging
 * output functions.
 * 
 * @author Patrick Peck
 * @version $Id$
 */
public class Logger {
  
  /**
   * Set the default hierarchy to which the <code>Logger</code> should send its
   * logging output.
   * @param hierarchy The logging defaultHierarchy.
   */
  public static void setHierarchy(String hierarchy) {
	  // there is no need for that anymore
  }


  /** The Constant instances. */
  private static final Map<String, org.slf4j.Logger> instances = new HashMap<String, org.slf4j.Logger>();

  /**
   * Gets the logger.
   *
   * @return the logger
   */
  private static synchronized org.slf4j.Logger getLogger() {
	  StackTraceElement[] stacktrace = Thread.currentThread().getStackTrace();

	  int i;
	  for(i = 2; i < stacktrace.length; i++)
          if(!stacktrace[i].getClassName().equals(Logger.class.getName()))
              break;

      String className = stacktrace[i].getClassName();

      org.slf4j.Logger logger = instances.get(className);
      if (logger != null) {
          return logger;
      }

      logger = org.slf4j.LoggerFactory.getLogger(className);
      instances.put(className, logger);

      return logger;
  }
  
  /**
   * Prepare the message for printing it as string.
   * <p>Mainly introduce because the <code>message</code> might be <code>null</code>. 
   *
   * @param message the message
   * @return the string
   */
  private static String prepareMessage(Object message) {
      if(null == message)
          return "no message given";
      return message.toString();
  }
  
  /**
   * Test, if the trace log level is enabled.
   * 
   * @return boolean <code>true</code>, if tracing output is enabled
   * <code>false</code> otherwise.
   */
  public static boolean isTraceEnabled() {
		org.slf4j.Logger logger = getLogger();
		return logger.isTraceEnabled();
  }
  
  /**
   * Test, if the trace log level is enabled for a given hierarchy.
   * 
   * @param hierarchy requested log hierarchy
   * @return boolean <code>true</code>, if tracing output is enabled
   * <code>false</code> otherwise.
   */
  public static boolean isTraceEnabled(String hierarchy) {
		org.slf4j.Logger logger = getLogger();
		return logger.isTraceEnabled();
  }
  
  /**
   * Trace a message.
   * 
   * @param message The message to trace.
   */
  public static void trace(Object message) {
		org.slf4j.Logger logger = getLogger();
		logger.trace(prepareMessage(message));
  }
  
  /**
   * Test, if the debug log level is enabled.
   * 
   * @return boolean <code>true</code>, if debug output is enabled
   * <code>false</code> otherwise.
   */
  public static boolean isDebugEnabled() {
		org.slf4j.Logger logger = getLogger();
		return logger.isDebugEnabled();
  }
  
  /**
   * Test, if the debug log level is enabled for a given hierarchy.
   * 
   * @param hierarchy requested log hierarchy
   * @return boolean <code>true</code>, if debug output is enabled
   * <code>false</code> otherwise.
   */
  public static boolean isDebugEnabled(String hierarchy) {
		org.slf4j.Logger logger = getLogger();
		return logger.isDebugEnabled();
  }
  
  /**
   * Log a debug message.
   * 
   * @param message The message to log.
   */
  public static void debug(Object message) {
		org.slf4j.Logger logger = getLogger();
		logger.debug(prepareMessage(message));
  }

/**
   * Log an info message.
   * 
   * @param message The message to log.
   */
  public static void info(Object message) {
		org.slf4j.Logger logger = getLogger();
		logger.info(prepareMessage(message));
  }
  
  /**
   * Info.
   *
   * @param string the string
   * @param args the objects
   */
  public static void info(String message, Object[] args) {
		org.slf4j.Logger logger = getLogger();
		logger.info(prepareMessage(message), args);
	}
  
  /**
   * Log a warning message.
   * 
   * @param message The message to log.
   */
  public static void warn(Object message) {
		org.slf4j.Logger logger = getLogger();
		logger.warn(prepareMessage(message));
  }

  /**
   * Log a warning message.
   * 
   * @param message The message to log.
   * @param t An exception that may be the cause of the warning.
   */
  public static void warn(Object message, Throwable t) {
		org.slf4j.Logger logger = getLogger();
		logger.warn(prepareMessage(message), t);
  }
  
  /**
   * Log an error message.
   * 
   * @param message The message to log.
   */
  public static void error(Object message) {
		org.slf4j.Logger logger = getLogger();
		logger.error(prepareMessage(message));
  }

  /**
   * Log an error message.
   * 
   * @param message The message to log.
   * @param t An exception that may be the cause of the error.
   */
  public static void error(Object message, Throwable t) {
		org.slf4j.Logger logger = getLogger();
		logger.error(prepareMessage(message), t);
  }
  
  /**
   * Log an error message with additional information.
   *
   * @param message The message to log.
   * @param variables The values to substitute {} of the logmessage with.
   */
  public static void error(Object message, Object[] variables) {
		org.slf4j.Logger logger = getLogger();
	  logger.error(prepareMessage(message), variables);
  }
  
  /**
   * Log a fatal error message.
   * 
   * @param message The message to log.
   */
  public static void fatal(Object message) {
		error(message);
  }

  /**
   * Log a fatal error message.
   * 
   * @param message The message to log.
   * @param t An exception that may be the cause of the error.
   */
  public static void fatal(Object message, Throwable t) {
		error(message, t);
  }
}