/**
    * Logback: the reliable, generic, fast and flexible logging framework.
    * Copyright (C) 1999-2011, 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 org.slf4j.impl;
  
  import org.slf4j.ILoggerFactory;
  import org.slf4j.LoggerFactory;
  import org.slf4j.helpers.Util;
  import org.slf4j.spi.LoggerFactoryBinder;
  
  import ch.qos.logback.classic.LoggerContext;
  import ch.qos.logback.classic.util.ContextInitializer;
  import ch.qos.logback.classic.util.ContextSelectorStaticBinder;
  import ch.qos.logback.core.CoreConstants;
  import ch.qos.logback.core.joran.spi.JoranException;
  import ch.qos.logback.core.util.StatusPrinter;
  
  /**
   * 
   * The binding of {@link LoggerFactory} class with an actual instance of
   * {@link ILoggerFactory} is performed using information returned by this class.
   * 
   * @author Ceki G&uuml;lc&uuml;</a>
   */
  public class StaticLoggerBinder implements LoggerFactoryBinder {
  
    /**
     * Declare the version of the SLF4J API this implementation is compiled
     * against. The value of this field is usually modified with each release.
     */
    // to avoid constant folding by the compiler, this field must *not* be final
    public static String REQUESTED_API_VERSION = "1.6"; // !final
  
    final static String NULL_CS_URL = CoreConstants.CODES_URL + "#null_CS";
  
    /**
     * The unique instance of this class.
     */
    private static StaticLoggerBinder SINGLETON = new StaticLoggerBinder();
  
    private static Object KEY = new Object();
  
    static {
      SINGLETON.init();
    }
  
    private boolean initialized = false;
    private LoggerContext defaultLoggerContext = new LoggerContext();
    private final ContextSelectorStaticBinder contextSelectorBinder = ContextSelectorStaticBinder
        .getSingleton();
  
    private StaticLoggerBinder() {
      defaultLoggerContext.setName(CoreConstants.DEFAULT_CONTEXT_NAME);
    }
  
    public static StaticLoggerBinder getSingleton() {
      return SINGLETON;
    }
  
    /**
     * Package access for testing purposes.
     */
    static void reset() {
      SINGLETON = new StaticLoggerBinder();
      SINGLETON.init();
    }
  
    /**
     * Package access for testing purposes.
     */
    void init() {
      try {
        try {
          new ContextInitializer(defaultLoggerContext).autoConfig();
        } catch (JoranException je) {
          Util.report("Failed to auto configure default logger context", je);
        }
        StatusPrinter.printInCaseOfErrorsOrWarnings(defaultLoggerContext);
        contextSelectorBinder.init(defaultLoggerContext, KEY);
        initialized = true;
      } catch (Throwable t) {
        // we should never get here
        Util.report("Failed to instantiate [" + LoggerContext.class.getName()
            + "]", t);
      }
    }
  
    public ILoggerFactory getLoggerFactory() {
      if (!initialized) {
       return defaultLoggerContext;
     }
 
     if (contextSelectorBinder.getContextSelector() == null) {
       throw new IllegalStateException(
           "contextSelector cannot be null. See also " + NULL_CS_URL);
     }
     return contextSelectorBinder.getContextSelector().getLoggerContext();
   }
 
   public String getLoggerFactoryClassStr() {
     return contextSelectorBinder.getContextSelector().getClass().getName();
   }
 
 }