/**
 ********************************************************************************
 * Copyright (c) 2019, 2020 Robert Bosch GmbH and others.
 *
 * This program and the accompanying materials are made
 * available under the terms of the Eclipse Public License 2.0
 * which is available at https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     Robert Bosch GmbH - initial API and implementation
 ********************************************************************************
 */
package org.eclipse.app4mc.transformation.log4j.configuration;

import java.io.File;

import org.apache.log4j.FileAppender;

/**
 * Custom Log4j appender that is writing log statements to a dedicated log file
 * if the system property <i>OUTPUT_DIRECTORY</i> is set. With this mechanism it
 * is possible to write a log file per migration session to a dedicated log file
 * only.
 */
public class TransformationFileAppender extends FileAppender {


	@Override
	protected boolean checkEntryConditions() {
		// we only append if an output directory is set
		String logFilePath = System.getProperty("APP4MC_TRANSFORMATION_LOG_FILE");
		if (logFilePath != null) {
			if (new File(logFilePath).canWrite()==false) { 
				return false;
			}
			super.setFile(logFilePath);
			super.activateOptions();

			return super.checkEntryConditions();
		}  
		return false;
	}

 
	@Override
	public void activateOptions() {
		// simply avoid the log warning for missing fileName configuration
		if (fileName != null) {
			super.activateOptions();
		}
	}

 
}