/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.logging.slf4j;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.spi.AbstractLoggerAdapter;
import org.apache.logging.log4j.spi.ExtendedLogger;
import org.apache.logging.log4j.spi.LoggerContext;
import org.slf4j.ILoggerFactory;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 *
 */
public class Log4jLoggerFactory extends AbstractLoggerAdapter<Logger> implements ILoggerFactory {

    private static final String FQCN = Log4jLoggerFactory.class.getName();
    private static final String PACKAGE = "org.slf4j";

    @Override
    protected Logger newLogger(final String name, final LoggerContext context) {
        final String key = Logger.ROOT_LOGGER_NAME.equals(name) ? LogManager.ROOT_LOGGER_NAME : name;
        return new Log4jLogger(context.getLogger(key), name);
    }

    @Override
    protected LoggerContext getContext() {
        final Throwable t = new Throwable();
        boolean next = false;
        boolean pkg = false;
        String fqcn = LoggerFactory.class.getName();
        // TODO: update with LOG4J2-809
        for (final StackTraceElement element : t.getStackTrace()) {
            if (FQCN.equals(element.getClassName())) {
                next = true;
                continue;
            }
            if (next && element.getClassName().startsWith(PACKAGE)) {
                fqcn = element.getClassName();
                pkg = true;
                continue;
            }
            if (pkg) {
                break;
            }
        }
        return PrivateManager.getContext(fqcn);
    }

    /**
     * The real bridge between SLF4J and Log4j.
     */
    private static class PrivateManager extends LogManager {
        private static final String FQCN = LoggerFactory.class.getName();

        public static LoggerContext getContext() {
            return getContext(FQCN, false);
        }

        public static LoggerContext getContext(final String fqcn) {
            return getContext(fqcn, false);
        }

        public static ExtendedLogger getLogger(final String name) {
            return getContext(FQCN).getLogger(name);
        }
    }
}

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.logging.slf4j;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.spi.AbstractLoggerAdapter;
import org.apache.logging.log4j.spi.ExtendedLogger;
import org.apache.logging.log4j.spi.LoggerContext;
import org.apache.logging.log4j.util.ReflectionUtil;
import org.slf4j.ILoggerFactory;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 *
 */
public class Log4jLoggerFactory extends AbstractLoggerAdapter<Logger> implements ILoggerFactory {

    private static final String FQCN = Log4jLoggerFactory.class.getName();
    private static final String PACKAGE = "org.slf4j";

    @Override
    protected Logger newLogger(final String name, final LoggerContext context) {
        final String key = Logger.ROOT_LOGGER_NAME.equals(name) ? LogManager.ROOT_LOGGER_NAME : name;
        return new Log4jLogger(context.getLogger(key), name);
    }

    @Override
    protected LoggerContext getContext() {
        return PrivateManager.getContext(ReflectionUtil.getCallerClass(FQCN, PACKAGE).getName());
    }

    /**
     * The real bridge between SLF4J and Log4j.
     */
    private static class PrivateManager extends LogManager {
        private static final String FQCN = LoggerFactory.class.getName();

        public static LoggerContext getContext() {
            return getContext(FQCN, false);
        }

        public static LoggerContext getContext(final String fqcn) {
            return getContext(fqcn, false);
        }

        public static ExtendedLogger getLogger(final String name) {
            return getContext(FQCN).getLogger(name);
        }
    }
}

Speed up log4j-slf4j-impl LoggerContext lookup.