/**
    * Copyright (c) 2004-2011 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;
  
  import java.io.IOException;
  import java.net.URL;
  import java.util.Arrays;
  import java.util.Enumeration;
  import java.util.Iterator;
  import java.util.LinkedHashSet;
  import java.util.List;
  import java.util.Set;
  
  import org.slf4j.helpers.NOPLoggerFactory;
  import org.slf4j.helpers.SubstituteLogger;
  import org.slf4j.helpers.SubstituteLoggerFactory;
  import org.slf4j.helpers.Util;
  import org.slf4j.impl.StaticLoggerBinder;
  
  /**
   * The <code>LoggerFactory</code> is a utility class producing Loggers for
   * various logging APIs, most notably for log4j, logback and JDK 1.4 logging.
   * Other implementations such as {@link org.slf4j.impl.NOPLogger NOPLogger} and
   * {@link org.slf4j.impl.SimpleLogger SimpleLogger} are also supported.
   * <p/>
   * <p/>
   * <code>LoggerFactory</code> is essentially a wrapper around an
   * {@link ILoggerFactory} instance bound with <code>LoggerFactory</code> at
   * compile time.
   * <p/>
   * <p/>
   * Please note that all methods in <code>LoggerFactory</code> are static.
   *
   *
   * @author Alexander Dorokhine
   * @author Robert Elliot
   * @author Ceki G&uuml;lc&uuml;
   *
   */
  public final class LoggerFactory {
  
    static final String CODES_PREFIX = "http://www.slf4j.org/codes.html";
  
    static final String NO_STATICLOGGERBINDER_URL = CODES_PREFIX + "#StaticLoggerBinder";
    static final String MULTIPLE_BINDINGS_URL = CODES_PREFIX + "#multiple_bindings";
    static final String NULL_LF_URL = CODES_PREFIX + "#null_LF";
    static final String VERSION_MISMATCH = CODES_PREFIX + "#version_mismatch";
    static final String SUBSTITUTE_LOGGER_URL = CODES_PREFIX + "#substituteLogger";
    static final String LOGGER_NAME_MISMATCH_URL = CODES_PREFIX + "#loggerNameMismatch";
  
    static final String UNSUCCESSFUL_INIT_URL = CODES_PREFIX + "#unsuccessfulInit";
    static final String UNSUCCESSFUL_INIT_MSG = "org.slf4j.LoggerFactory could not be successfully initialized. See also "
        + UNSUCCESSFUL_INIT_URL;
  
    static final int UNINITIALIZED = 0;
    static final int ONGOING_INITIALIZATION = 1;
    static final int FAILED_INITIALIZATION = 2;
    static final int SUCCESSFUL_INITIALIZATION = 3;
    static final int NOP_FALLBACK_INITIALIZATION = 4;
  
    static int INITIALIZATION_STATE = UNINITIALIZED;
    static SubstituteLoggerFactory TEMP_FACTORY = new SubstituteLoggerFactory();
    static NOPLoggerFactory NOP_FALLBACK_FACTORY = new NOPLoggerFactory();
  
    // Support for detecting mismatched logger names.
    static final String DETECT_LOGGER_NAME_MISMATCH_PROPERTY = "slf4j.detectLoggerNameMismatch";
    static boolean DETECT_LOGGER_NAME_MISMATCH = Boolean.getBoolean(DETECT_LOGGER_NAME_MISMATCH_PROPERTY);
  
    /**
     * It is LoggerFactory's responsibility to track version changes and manage
     * the compatibility list.
     * <p/>
     * <p/>
     * It is assumed that all versions in the 1.6 are mutually compatible.
     */
    static private final String[] API_COMPATIBILITY_LIST = new String[] { "1.6", "1.7" };
  
   // private constructor prevents instantiation
   private LoggerFactory() {
   }
 
   /**
    * Force LoggerFactory to consider itself uninitialized.
    * <p/>
    * <p/>
    * This method is intended to be called by classes (in the same package) for
    * testing purposes. This method is internal. It can be modified, renamed or
    * removed at any time without notice.
    * <p/>
    * <p/>
    * You are strongly discouraged from calling this method in production code.
    */
   static void reset() {
     INITIALIZATION_STATE = UNINITIALIZED;
     TEMP_FACTORY = new SubstituteLoggerFactory();
   }
 
   private final static void performInitialization() {
     bind();
     if (INITIALIZATION_STATE == SUCCESSFUL_INITIALIZATION) {
       versionSanityCheck();
     }
   }
 
   private static boolean messageContainsOrgSlf4jImplStaticLoggerBinder(String msg) {
     if (msg == null)
       return false;
     if (msg.indexOf("org/slf4j/impl/StaticLoggerBinder") != -1)
       return true;
     if (msg.indexOf("org.slf4j.impl.StaticLoggerBinder") != -1)
       return true;
     return false;
   }
 
   private final static void bind() {
     try {
       Set<URL> staticLoggerBinderPathSet = findPossibleStaticLoggerBinderPathSet();
       reportMultipleBindingAmbiguity(staticLoggerBinderPathSet);
       // the next line does the binding
       StaticLoggerBinder.getSingleton();
       INITIALIZATION_STATE = SUCCESSFUL_INITIALIZATION;
       reportActualBinding(staticLoggerBinderPathSet);
       fixSubstitutedLoggers();
     } catch (NoClassDefFoundError ncde) {
       String msg = ncde.getMessage();
       if (messageContainsOrgSlf4jImplStaticLoggerBinder(msg)) {
         INITIALIZATION_STATE = NOP_FALLBACK_INITIALIZATION;
         Util.report("Failed to load class \"org.slf4j.impl.StaticLoggerBinder\".");
         Util.report("Defaulting to no-operation (NOP) logger implementation");
         Util.report("See " + NO_STATICLOGGERBINDER_URL + " for further details.");
       } else {
         failedBinding(ncde);
         throw ncde;
       }
     } catch (java.lang.NoSuchMethodError nsme) {
       String msg = nsme.getMessage();
       if (msg != null && msg.indexOf("org.slf4j.impl.StaticLoggerBinder.getSingleton()") != -1) {
         INITIALIZATION_STATE = FAILED_INITIALIZATION;
         Util.report("slf4j-api 1.6.x (or later) is incompatible with this binding.");
         Util.report("Your binding is version 1.5.5 or earlier.");
         Util.report("Upgrade your binding to version 1.6.x.");
       }
       throw nsme;
     } catch (Exception e) {
       failedBinding(e);
       throw new IllegalStateException("Unexpected initialization failure", e);
     }
   }
 
   static void failedBinding(Throwable t) {
     INITIALIZATION_STATE = FAILED_INITIALIZATION;
     Util.report("Failed to instantiate SLF4J LoggerFactory", t);
   }
 
   private final static void fixSubstitutedLoggers() {
     List<SubstituteLogger> loggers = TEMP_FACTORY.getLoggers();
 
     if (loggers.isEmpty()) {
       return;
     }
 
     Util.report("The following set of substitute loggers may have been accessed");
     Util.report("during the initialization phase. Logging calls during this");
     Util.report("phase were not honored. However, subsequent logging calls to these");
     Util.report("loggers will work as normally expected.");
     Util.report("See also " + SUBSTITUTE_LOGGER_URL);
     for (SubstituteLogger subLogger : loggers) {
       subLogger.setDelegate(getLogger(subLogger.getName()));
       Util.report(subLogger.getName());
     }
 
     TEMP_FACTORY.clear();
   }
 
   private final static void versionSanityCheck() {
     try {
       String requested = StaticLoggerBinder.REQUESTED_API_VERSION;
 
       boolean match = false;
       for (int i = 0; i < API_COMPATIBILITY_LIST.length; i++) {
         if (requested.startsWith(API_COMPATIBILITY_LIST[i])) {
           match = true;
         }
       }
       if (!match) {
         Util.report("The requested version " + requested + " by your slf4j binding is not compatible with "
             + Arrays.asList(API_COMPATIBILITY_LIST).toString());
         Util.report("See " + VERSION_MISMATCH + " for further details.");
       }
     } catch (java.lang.NoSuchFieldError nsfe) {
       // given our large user base and SLF4J's commitment to backward
       // compatibility, we cannot cry here. Only for implementations
       // which willingly declare a REQUESTED_API_VERSION field do we
       // emit compatibility warnings.
     } catch (Throwable e) {
       // we should never reach here
       Util.report("Unexpected problem occured during version sanity check", e);
     }
   }
 
   // We need to use the name of the StaticLoggerBinder class, but we can't reference
   // the class itself.
   private static String STATIC_LOGGER_BINDER_PATH = "org/slf4j/impl/StaticLoggerBinder.class";
 
   private static Set<URL> findPossibleStaticLoggerBinderPathSet() {
     // use Set instead of list in order to deal with bug #138
     // LinkedHashSet appropriate here because it preserves insertion order during iteration
     Set<URL> staticLoggerBinderPathSet = new LinkedHashSet<URL>();
     try {
       ClassLoader loggerFactoryClassLoader = LoggerFactory.class.getClassLoader();
       Enumeration<URL> paths;
       if (loggerFactoryClassLoader == null) {
         paths = ClassLoader.getSystemResources(STATIC_LOGGER_BINDER_PATH);
       } else {
         paths = loggerFactoryClassLoader.getResources(STATIC_LOGGER_BINDER_PATH);
       }
       while (paths.hasMoreElements()) {
         URL path = (URL) paths.nextElement();
         staticLoggerBinderPathSet.add(path);
       }
     } catch (IOException ioe) {
       Util.report("Error getting resources from path", ioe);
     }
     return staticLoggerBinderPathSet;
   }
 
   private static boolean isAmbiguousStaticLoggerBinderPathSet(Set<URL> staticLoggerBinderPathSet) {
     return staticLoggerBinderPathSet.size() > 1;
   }
 
   /**
    * Prints a warning message on the console if multiple bindings were found on the class path.
    * No reporting is done otherwise.
    *
    */
   private static void reportMultipleBindingAmbiguity(Set<URL> staticLoggerBinderPathSet) {
     if (isAmbiguousStaticLoggerBinderPathSet(staticLoggerBinderPathSet)) {
       Util.report("Class path contains multiple SLF4J bindings.");
       Iterator<URL> iterator = staticLoggerBinderPathSet.iterator();
       while (iterator.hasNext()) {
         URL path = (URL) iterator.next();
         Util.report("Found binding in [" + path + "]");
       }
       Util.report("See " + MULTIPLE_BINDINGS_URL + " for an explanation.");
     }
   }
 
   private static void reportActualBinding(Set<URL> staticLoggerBinderPathSet) {
     if (isAmbiguousStaticLoggerBinderPathSet(staticLoggerBinderPathSet)) {
       Util.report("Actual binding is of type [" + StaticLoggerBinder.getSingleton().getLoggerFactoryClassStr() + "]");
     }
   }
 
   /**
    * Return a logger named according to the name parameter using the statically
    * bound {@link ILoggerFactory} instance.
    *
    * @param name The name of the logger.
    * @return logger
    */
   public static Logger getLogger(String name) {
     ILoggerFactory iLoggerFactory = getILoggerFactory();
     return iLoggerFactory.getLogger(name);
   }
 
   /**
    * Return a logger named corresponding to the class passed as parameter, using
    * the statically bound {@link ILoggerFactory} instance.
    *
    * <p>In case the the <code>clazz</code> parameter differs from the name of
    * the caller as computed internally by SLF4J, a logger name mismatch warning will be 
    * printed but only if the <code>slf4j.detectLoggerNameMismatch</code> system property is 
    * set to true. By default, this property is not set and no warnings will be printed
    * even in case of a logger name mismatch.
    * 
    * @param clazz the returned logger will be named after clazz
    * @return logger
    *
    *
    * @see <a href="http://www.slf4j.org/codes.html#loggerNameMismatch">Detected logger name mismatch</a> 
    */
   public static Logger getLogger(Class<?> clazz) {
     Logger logger = getLogger(clazz.getName());
     if (DETECT_LOGGER_NAME_MISMATCH) {
       Class<?> autoComputedCallingClass = Util.getCallingClass();
       if (nonMatchingClasses(clazz, autoComputedCallingClass)) {
         Util.report(String.format("Detected logger name mismatch. Given name: \"%s\"; computed name: \"%s\".",
             logger.getName(), autoComputedCallingClass.getName()));
         Util.report("See " + LOGGER_NAME_MISMATCH_URL + " for an explanation");
       }
     }
     return logger;
   }
 
   private static boolean nonMatchingClasses(Class<?> clazz, Class<?> autoComputedCallingClass) {
     return !autoComputedCallingClass.isAssignableFrom(clazz);
   }
 
   /**
    * Return the {@link ILoggerFactory} instance in use.
    * <p/>
    * <p/>
    * ILoggerFactory instance is bound with this class at compile time.
    *
    * @return the ILoggerFactory instance in use
    */
   public static ILoggerFactory getILoggerFactory() {
     if (INITIALIZATION_STATE == UNINITIALIZED) {
       INITIALIZATION_STATE = ONGOING_INITIALIZATION;
       performInitialization();
     }
     switch (INITIALIZATION_STATE) {
     case SUCCESSFUL_INITIALIZATION:
       return StaticLoggerBinder.getSingleton().getLoggerFactory();
     case NOP_FALLBACK_INITIALIZATION:
       return NOP_FALLBACK_FACTORY;
     case FAILED_INITIALIZATION:
       throw new IllegalStateException(UNSUCCESSFUL_INIT_MSG);
     case ONGOING_INITIALIZATION:
       // support re-entrant behavior.
       // See also http://bugzilla.slf4j.org/show_bug.cgi?id=106
       return TEMP_FACTORY;
     }
     throw new IllegalStateException("Unreachable code");
   }
 }