/*
 * Copyright 1999-2005 The Apache Software Foundation.
 * 
 * Licensed 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.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 <code>OnlyOnceErrorHandler</code> 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.

   <p>The error message is printed on <code>System.err</code>. 

   <p>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
     <code>System.err</code>.  */
  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
     <code>System.err</code>.
   */
  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
     <code>System.err</code>.  
  */
  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) {
  }
}