/*
 * Copyright (C) The Apache Software Foundation. All rights reserved.
 *
 * This software is published under the terms of the Apache Software License
 * version 1.1, a copy of which has been included  with this distribution in
 * the LICENSE.txt file.
 */

package org.apache.log4j.helpers;

import  org.apache.log4j.spi.ErrorHandler;
import  org.apache.log4j.spi.LoggingEvent;
import  org.apache.log4j.Logger;
import  org.apache.log4j.Appender;

/**

   The OnlyOnceErrorHandler implements log4j's default
   error handling policy which consists of emitting a message for the
   first error in an appender and ignoring all following errors.

   
The error message is printed on System.err. 

   
This policy aims at protecting an otherwise working application
   from being flooded with error messages when logging fails.

   @author Ceki Gülcü
   @since 0.9.0 */
public class OnlyOnceErrorHandler implements ErrorHandler {


  final String WARN_PREFIX = "log4j warning: ";
  final String ERROR_PREFIX = "log4j error: ";

  boolean firstTime = true;


  /**
     Does not do anything.
   */
  public 
  void setLogger(Logger logger) {
  }


  /**
     No options to activate.
  */
  public 
  void activateOptions() {
  }


  /**
     Prints the message and the stack trace of the exception on
     System.err.  */
  public
  void error(String message, Exception e, int errorCode) { 
    error(message, e, errorCode, null);
  }

  /**
     Prints the message and the stack trace of the exception on
     System.err.
   */
  public
  void error(String message, Exception e, int errorCode, LoggingEvent event) {
    if(firstTime) {
      LogLog.error(message, e);
      firstTime = false;
    }
  }


  /**
     Print a the error message passed as parameter on
     System.err.  
  */
  public 
  void error(String message) {
    if(firstTime) {
      LogLog.error(message);
      firstTime = false;
    }
  }
  
  /**
     Does not do anything.
   */
  public
  void setAppender(Appender appender) {
  }

  /**
     Does not do anything.
   */
  public
  void setBackupAppender(Appender appender) {
  }
}