/*

  * #%L

  * Slf4jLogFactory.java - mongodb-async-driver - Allanbank Consulting, Inc.

  * %%

  * Copyright (C) 2011 - 2014 Allanbank Consulting, Inc.

  * %%

  * 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.

  * #L%

  */

 package com.allanbank.mongodb.util.log;

 import java.lang.reflect.InvocationTargetException;

 import java.lang.reflect.Method;

 import java.util.logging.Level;

 import java.util.logging.Logger;

 /**

  * Slf4jLogFactory provides factory to create {@link Slf4jLog} instances.

  * 

  * @api.no This class is <b>NOT</b> part of the drivers API. This class may be

  *         mutated in incompatible ways between any two releases of the driver.

  * @copyright 2014, Allanbank Consulting, Inc., All Rights Reserved

  */

 public class Slf4jLogFactory extends LogFactory {

     /** The <code>LocationAwareLogger</code> class. */

     private final Class<?> myLocationAwareLoggerClass;

     /**

      * The <code>getLogger(Class)</code> method from the

      * <code>LoggerFactory</code> interface.

      */

     private final Method myLogFactoryMethod;

     /**

      * The <code>log(Marker, String, int, String, Object[])</code> method from

      * the <code>LocationAwareLogger</code> interface.

      */

     private final Method myLogMethod;

     /**

      * Creates a new Slf4jLogFactory.

      * 

      * @throws RuntimeException

      *             On a failure to find the SLF4J Logger.

      */

     public Slf4jLogFactory() throws RuntimeException {

         Class<?> logFactoryClass;

         try {

             logFactoryClass = Class.forName("org.slf4j.LoggerFactory");

         }

         catch (final ClassNotFoundException e) {

             // Don't log. SLF4J is not on the classpath to use.

             throw new RuntimeException(e);

         }

         try {

             myLogFactoryMethod = logFactoryClass.getMethod("getLogger",

                     Class.class);

             myLocationAwareLoggerClass = Class

                     .forName("org.slf4j.spi.LocationAwareLogger");

             final Class<?> markerClass = Class.forName("org.slf4j.Marker");

             myLogMethod = myLocationAwareLoggerClass.getMethod("log",

                     markerClass, String.class, int.class, String.class,

                     Object[].class, Throwable.class);

         }

         catch (final ClassNotFoundException e) {

             Logger.getLogger(Slf4jLogFactory.class.getName()).log(

                     Level.WARNING,

                     "Failed bootstrap the SLF4J logger: " + e.getMessage(), e);

             throw new RuntimeException(e);

         }

         catch (final NoSuchMethodException e) {

             Logger.getLogger(Slf4jLogFactory.class.getName()).log(

                     Level.WARNING,

                     "Failed bootstrap the SLF4J logger: " + e.getMessage(), e);

             throw new RuntimeException(e);

         }

     }

     /**

      * {@inheritDoc}

      * <p>

      * Overridden to return a {@link Slf4jLog} instance if SLF4J LoggerFactory

      * returns a LocationAwareLogger instance. Otherwise a {@link JulLog} is

      * returned.

      * </p>

      */

     @Override

     protected Log doGetLog(final Class<?> clazz) {

         Log log = null;

         try {

             final Object logger = myLogFactoryMethod.invoke(null, clazz);

             if (myLocationAwareLoggerClass.isInstance(logger)) {

                 log = new Slf4jLog(myLogMethod, logger);

             }

         }

         catch (final IllegalAccessException e) {

             // Fall through.

         }

         catch (final InvocationTargetException e) {

             // Fall through.

         }

         catch (final RuntimeException e) {

             // Fall through.

         }

         // Fall back to JUL logging.

         if (log == null) {

             Logger.getLogger(Slf4jLogFactory.class.getName()).warning(

                     "Falling back to the JUL logger.");

             log = new JulLog(clazz);

         }

         return log;

     }

 }