/*
 * Copyright (c) 2004-2008 QOS.ch
 * All rights reserved.
 * 
 * Permission is hereby granted, free  of charge, to any person obtaining
 * a  copy  of this  software  and  associated  documentation files  (the
 * "Software"), to  deal in  the Software without  restriction, including
 * without limitation  the rights to  use, copy, modify,  merge, publish,
 * distribute,  sublicense, and/or sell  copies of  the Software,  and to
 * permit persons to whom the Software  is furnished to do so, subject to
 * the following conditions:
 * 
 * The  above  copyright  notice  and  this permission  notice  shall  be
 * included in all copies or substantial portions of the Software.
 * 
 * THE  SOFTWARE IS  PROVIDED  "AS  IS", WITHOUT  WARRANTY  OF ANY  KIND,
 * EXPRESS OR  IMPLIED, INCLUDING  BUT NOT LIMITED  TO THE  WARRANTIES OF
 * MERCHANTABILITY,    FITNESS    FOR    A   PARTICULAR    PURPOSE    AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE,  ARISING FROM, OUT OF OR IN CONNECTION
 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */


package org.slf4j.impl;

import java.io.Serializable;

import org.apache.log4j.Level;
import org.slf4j.Logger;
import org.slf4j.Marker;
import org.slf4j.helpers.MarkerIgnoringBase;
import org.slf4j.helpers.MessageFormatter;
import org.slf4j.spi.LocationAwareLogger;

/**
 * A wrapper over {@link org.apache.log4j.Logger org.apache.log4j.Logger} in
 * conforming to the {@link Logger} interface. 
 * 
 * <p>Note that the logging levels mentioned in this class refer to those defined in the <a
 * href="http://logging.apache.org/log4j/docs/api/org/apache/log4j/Level.html"><code>org.apache.log4j.Level</code></a>
 * class.
 * 
 * <p>
 * The TRACE level was introduced in log4j version 1.2.12. In order to avoid
 * crashing the host application, in the case the log4j version in use predates
 * 1.2.12, the TRACE level will be mapped as DEBUG. See also <a
 * href="http://bugzilla.slf4j.org/show_bug.cgi?id=68">bug 68</a>.
 * 
 * @author Ceki G&uuml;lc&uuml;
 */
public final class Log4jLoggerAdapter extends MarkerIgnoringBase implements
    LocationAwareLogger, Serializable {

  private static final long serialVersionUID = 6182834493563598289L;

  final transient org.apache.log4j.Logger logger;

  /**
   * Following the pattern discussed in pages 162 through 168 of "The complete
   * log4j manual".
   */
  final static String FQCN = Log4jLoggerAdapter.class.getName();

  // Does the log4j version in use recognize the TRACE level?
  // The trace level was introduced in log4j 1.2.12.
  final boolean traceCapable;

  // WARN: Log4jLoggerAdapter constructor should have only package access so
  // that
  // only Log4jLoggerFactory be able to create one.
  Log4jLoggerAdapter(org.apache.log4j.Logger logger) {
    this.logger = logger;
    this.name = logger.getName();
    traceCapable = isTraceCapable();
  }

  private boolean isTraceCapable() {
    try {
      logger.isTraceEnabled();
      return true;
    } catch (NoSuchMethodError e) {
      return false;
    }
  }

  /**
   * Is this logger instance enabled for the TRACE level?
   * 
   * @return True if this Logger is enabled for level TRACE, false otherwise.
   */
  public boolean isTraceEnabled() {
    if (traceCapable) {
      return logger.isTraceEnabled();
    } else {
      return logger.isDebugEnabled();
    }
  }

  /**
   * Log a message object at level TRACE.
   * 
   * @param msg -
   *                the message object to be logged
   */
  public void trace(String msg) {
    logger.log(FQCN, traceCapable ? Level.TRACE : Level.DEBUG, msg, null);
  }

  /**
   * Log a message at level TRACE according to the specified format and
   * argument.
   * 
   * <p>
   * This form avoids superfluous object creation when the logger is disabled
   * for level TRACE.
   * </p>
   * 
   * @param format
   *                the format string
   * @param arg
   *                the argument
   */
  public void trace(String format, Object arg) {
    if (isTraceEnabled()) {
      String msgStr = MessageFormatter.format(format, arg);
      logger.log(FQCN, traceCapable ? Level.TRACE : Level.DEBUG, msgStr, null);
    }
  }

  /**
   * Log a message at level TRACE according to the specified format and
   * arguments.
   * 
   * <p>
   * This form avoids superfluous object creation when the logger is disabled
   * for the TRACE level.
   * </p>
   * 
   * @param format
   *                the format string
   * @param arg1
   *                the first argument
   * @param arg2
   *                the second argument
   */
  public void trace(String format, Object arg1, Object arg2) {
    if (isTraceEnabled()) {
      String msgStr = MessageFormatter.format(format, arg1, arg2);
      logger.log(FQCN, traceCapable ? Level.TRACE : Level.DEBUG, msgStr, null);
    }
  }

  /**
   * Log a message at level TRACE according to the specified format and
   * arguments.
   * 
   * <p>
   * This form avoids superfluous object creation when the logger is disabled
   * for the TRACE level.
   * </p>
   * 
   * @param format
   *                the format string
   * @param argArray
   *                an array of arguments
   */
  public void trace(String format, Object[] argArray) {
    if (isTraceEnabled()) {
      String msgStr = MessageFormatter.arrayFormat(format, argArray);
      logger.log(FQCN, traceCapable ? Level.TRACE : Level.DEBUG, msgStr, null);
    }
  }

  /**
   * Log an exception (throwable) at level TRACE with an accompanying message.
   * 
   * @param msg
   *                the message accompanying the exception
   * @param t
   *                the exception (throwable) to log
   */
  public void trace(String msg, Throwable t) {
    logger.log(FQCN, traceCapable ? Level.TRACE : Level.DEBUG, msg, t);
  }

  /**
   * Is this logger instance enabled for the DEBUG level?
   * 
   * @return True if this Logger is enabled for level DEBUG, false otherwise.
   */
  public boolean isDebugEnabled() {
    return logger.isDebugEnabled();
  }

  /**
   * Log a message object at level DEBUG.
   * 
   * @param msg -
   *                the message object to be logged
   */
  public void debug(String msg) {
    logger.log(FQCN, Level.DEBUG, msg, null);
  }

  /**
   * Log a message at level DEBUG according to the specified format and
   * argument.
   * 
   * <p>
   * This form avoids superfluous object creation when the logger is disabled
   * for level DEBUG.
   * </p>
   * 
   * @param format
   *                the format string
   * @param arg
   *                the argument
   */
  public void debug(String format, Object arg) {
    if (logger.isDebugEnabled()) {
      String msgStr = MessageFormatter.format(format, arg);
      logger.log(FQCN, Level.DEBUG, msgStr, null);
    }
  }

  /**
   * Log a message at level DEBUG according to the specified format and
   * arguments.
   * 
   * <p>
   * This form avoids superfluous object creation when the logger is disabled
   * for the DEBUG level.
   * </p>
   * 
   * @param format
   *                the format string
   * @param arg1
   *                the first argument
   * @param arg2
   *                the second argument
   */
  public void debug(String format, Object arg1, Object arg2) {
    if (logger.isDebugEnabled()) {
      String msgStr = MessageFormatter.format(format, arg1, arg2);
      logger.log(FQCN, Level.DEBUG, msgStr, null);
    }
  }

  /**
   * Log a message at level DEBUG according to the specified format and
   * arguments.
   * 
   * <p>
   * This form avoids superfluous object creation when the logger is disabled
   * for the DEBUG level.
   * </p>
   * 
   * @param format
   *                the format string
   * @param argArray
   *                an array of arguments
   */
  public void debug(String format, Object[] argArray) {
    if (logger.isDebugEnabled()) {
      String msgStr = MessageFormatter.arrayFormat(format, argArray);
      logger.log(FQCN, Level.DEBUG, msgStr, null);
    }
  }

  /**
   * Log an exception (throwable) at level DEBUG with an accompanying message.
   * 
   * @param msg
   *                the message accompanying the exception
   * @param t
   *                the exception (throwable) to log
   */
  public void debug(String msg, Throwable t) {
    logger.log(FQCN, Level.DEBUG, msg, t);
  }

  /**
   * Is this logger instance enabled for the INFO level?
   * 
   * @return True if this Logger is enabled for the INFO level, false otherwise.
   */
  public boolean isInfoEnabled() {
    return logger.isInfoEnabled();
  }

  /**
   * Log a message object at the INFO level.
   * 
   * @param msg -
   *                the message object to be logged
   */
  public void info(String msg) {
    logger.log(FQCN, Level.INFO, msg, null);
  }