/**
 * Logback: the reliable, generic, fast and flexible logging framework.
 * Copyright (C) 1999-2015, QOS.ch. All rights reserved.
 *
 * This program and the accompanying materials are dual-licensed under
 * either the terms of the Eclipse Public License v1.0 as published by
 * the Eclipse Foundation
 *
 *   or (per the licensee's choosing)
 *
 * under the terms of the GNU Lesser General Public License version 2.1
 * as published by the Free Software Foundation.
 */
package ch.qos.logback.classic.jul;

import ch.qos.logback.classic.Level;
import ch.qos.logback.classic.Logger;
import ch.qos.logback.classic.LoggerContext;
import ch.qos.logback.classic.spi.LoggerContextListener;
import ch.qos.logback.core.spi.ContextAwareBase;
import ch.qos.logback.core.spi.LifeCycle;

import java.util.Enumeration;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import java.util.logging.LogManager;


/**
 * Propagate level changes made to a logback logger into the equivalent logger in j.u.l.
 */
public class LevelChangePropagator extends ContextAwareBase implements LoggerContextListener, LifeCycle {

  private Set julLoggerSet = new HashSet();
  boolean isStarted = false;
  boolean resetJUL = false;

  public void setResetJUL(boolean resetJUL) {
    this.resetJUL = resetJUL;
  }
  
  public boolean isResetResistant() {
    return false;
  }

  public void onStart(LoggerContext context) {
  }

  public void onReset(LoggerContext context) {
  }

  public void onStop(LoggerContext context) {
  }

  public void onLevelChange(Logger logger, Level level) {
    propagate(logger, level);
  }

  private void propagate(Logger logger, Level level) {
    addInfo("Propagating " + level + " level on " + logger + " onto the JUL framework");
    java.util.logging.Logger julLogger = JULHelper.asJULLogger(logger);
    // prevent garbage collection of jul loggers whose level we set
    // see also  http://jira.qos.ch/browse/LBCLASSIC-256
    julLoggerSet.add(julLogger);
    java.util.logging.Level julLevel = JULHelper.asJULLevel(level);
    julLogger.setLevel(julLevel);
  }

  public void resetJULLevels() {
    LogManager lm = LogManager.getLogManager();

    Enumeration e = lm.getLoggerNames();
    while (e.hasMoreElements()) {
      String loggerName = (String) e.nextElement();
      java.util.logging.Logger julLogger = lm.getLogger(loggerName);
      if (JULHelper.isRegularNonRootLogger(julLogger) && julLogger.getLevel() != null) {
        addInfo("Setting level of jul logger [" + loggerName + "] to null");
        julLogger.setLevel(null);
      }
    }
  }

  private void propagateExistingLoggerLevels() {
    LoggerContext loggerContext = (LoggerContext) context;
    List<Logger> loggerList = loggerContext.getLoggerList();
    for (Logger l : loggerList) {
      if (l.getLevel() != null) {
        propagate(l, l.getLevel());
      }
    }
  }

  public void start() {
    if (resetJUL) {
      resetJULLevels();
    }
    propagateExistingLoggerLevels();

    isStarted = true;
  }

  public void stop() {
    isStarted = false;
  }

  public boolean isStarted() {
    return isStarted;
  }
}
