/*
 * Copyright 2012-2019 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
 *
 *      https://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.log4j2;

import org.apache.logging.log4j.core.LoggerContext;
import org.apache.logging.log4j.core.config.Configuration;
import org.apache.logging.log4j.core.config.ConfigurationFactory;
import org.apache.logging.log4j.core.config.ConfigurationSource;
import org.apache.logging.log4j.core.config.DefaultConfiguration;
import org.apache.logging.log4j.core.config.Order;
import org.apache.logging.log4j.core.config.plugins.Plugin;

import org.springframework.boot.logging.LoggingSystem;

/**
 * Spring Boot {@link ConfigurationFactory} that customizes Log4J2's default configuration
 * to:
 *
 * <ol>
 * <li>Prevent logger warnings from being printed when the application first starts.
 * <li>Disable its shutdown hook
 * </ol>
 *
 * This factory is ordered last and is triggered by a {@code log4j2.springboot} classpath
 * resource (which is bundled in this jar). If the {@link Log4J2LoggingSystem} is active,
 * a custom {@link DefaultConfiguration} is returned with the expectation that the system
 * will later re-initialize Log4J2 with the correct configuration file.
 *
 * @author Phillip Webb
 * @since 1.5.0
 */
@Plugin(name = "SpringBootConfigurationFactory", category = ConfigurationFactory.CATEGORY)
@Order(0)
public class SpringBootConfigurationFactory extends ConfigurationFactory {

	private static final String[] TYPES = { ".springboot" };

	@Override
	protected String[] getSupportedTypes() {
		return TYPES;
	}

	@Override
	public Configuration getConfiguration(LoggerContext loggerContext, ConfigurationSource source) {
		if (source != null && source != ConfigurationSource.NULL_SOURCE
				&& LoggingSystem.get(loggerContext.getClass().getClassLoader()) != null) {
			return new SpringBootConfiguration();
		}
		return null;
	}

	private static final class SpringBootConfiguration extends DefaultConfiguration {

		private SpringBootConfiguration() {
			this.isShutdownHookEnabled = false;
		}

	}

}
