/*
 * Copyright 2012-2013 the original author or authors.
 *
 * 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.springframework.boot.logging.logback;

import java.net.URL;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;

import org.slf4j.ILoggerFactory;
import org.slf4j.Logger;
import org.slf4j.bridge.SLF4JBridgeHandler;
import org.slf4j.impl.StaticLoggerBinder;
import org.springframework.boot.logging.AbstractLoggingSystem;
import org.springframework.boot.logging.LogLevel;
import org.springframework.boot.logging.LoggingSystem;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
import org.springframework.util.ResourceUtils;
import org.springframework.util.StringUtils;
import org.springframework.util.SystemPropertyUtils;

import ch.qos.logback.classic.Level;
import ch.qos.logback.classic.LoggerContext;
import ch.qos.logback.classic.util.ContextInitializer;

/**
 * {@link LoggingSystem} for for <a href="http://logback.qos.ch">logback</a>.
 * 
 * @author Phillip Webb
 * @author Dave Syer
 */
public class LogbackLoggingSystem extends AbstractLoggingSystem {

	private static final Map<LogLevel, Level> LEVELS;
	static {
		Map<LogLevel, Level> levels = new HashMap<LogLevel, Level>();
		levels.put(LogLevel.TRACE, Level.TRACE);
		levels.put(LogLevel.DEBUG, Level.DEBUG);
		levels.put(LogLevel.INFO, Level.INFO);
		levels.put(LogLevel.WARN, Level.WARN);
		levels.put(LogLevel.ERROR, Level.ERROR);
		levels.put(LogLevel.FATAL, Level.ERROR);
		LEVELS = Collections.unmodifiableMap(levels);
	}

	public LogbackLoggingSystem(ClassLoader classLoader) {
		super(classLoader, "logback-test.groovy", "logback-test.xml", "logback.groovy",
				"logback.xml");
	}

	@Override
	public void beforeInitialize() {
		super.beforeInitialize();
		if (ClassUtils.isPresent("org.slf4j.bridge.SLF4JBridgeHandler", getClassLoader())) {
			SLF4JBridgeHandler.removeHandlersForRootLogger();
			SLF4JBridgeHandler.install();
		}
	}

	@Override
	public void initialize(String configLocation) {
		Assert.notNull(configLocation, "ConfigLocation must not be null");
		String resolvedLocation = SystemPropertyUtils.resolvePlaceholders(configLocation);
		ILoggerFactory factory = StaticLoggerBinder.getSingleton().getLoggerFactory();
		Assert.isInstanceOf(ILoggerFactory.class, factory);
		LoggerContext context = (LoggerContext) factory;
		context.stop();
		try {
			URL url = ResourceUtils.getURL(resolvedLocation);
			new ContextInitializer(context).configureByResource(url);
		}
		catch (Exception ex) {
			throw new IllegalStateException("Could not initialize logging from "
					+ configLocation, ex);
		}
	}

	@Override
	public void setLogLevel(String loggerName, LogLevel level) {
		ILoggerFactory factory = StaticLoggerBinder.getSingleton().getLoggerFactory();
		Logger logger = factory
				.getLogger(StringUtils.isEmpty(loggerName) ? Logger.ROOT_LOGGER_NAME
						: loggerName);
		((ch.qos.logback.classic.Logger) logger).setLevel(LEVELS.get(level));
	}

}

@@ -2816,37 +2816,219 @@
 eOf(
-ILoggerFactory.class, factory
+%0A%09%09%09%09LoggerContext.class,%0A%09%09%09%09factory,%0A%09%09%09%09%22LoggerFactory is not a Logback LoggerContext but Logback is on the classpath. Either remove Logback or the competing implementation (%22%0A%09%09%09%09%09%09+ factory.getClass() + %22)%22
 );%0A%09

Add instanceof check and nice fat error message