/*
 * Copyright 2003 Federal Chancellery Austria
 * MOA-ID has been developed in a cooperation between BRZ, the Federal
 * Chancellery Austria - ICT staff unit, and Graz University of Technology.
 *
 * Licensed under the EUPL, Version 1.1 or - as soon they will be approved by
 * the European Commission - subsequent versions of the EUPL (the "Licence");
 * You may not use this work except in compliance with the Licence.
 * You may obtain a copy of the Licence at:
 * http://www.osor.eu/eupl/
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the Licence is distributed on an "AS IS" basis,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the Licence for the specific language governing permissions and
 * limitations under the Licence.
 *
 * This product combines work with different licenses. See the "NOTICE" text
 * file for details on the various modules and licenses.
 * The "NOTICE" text file is part of the distribution. Any derivative works
 * that you distribute must include a readable copy of the "NOTICE" text file.
 */

package at.gv.egovernment.moaspss.logging;

import java.util.HashMap;
import java.util.Map;

/**
 * A utility class acting as a facade to the logging subsystem.
 *
 * Configure the logging defaultHierarchy that the <code>Logger</code> uses by
 * calling <code>setHierarchy</code> once before calling any of the logging
 * output functions.
 *
 * @author Patrick Peck
 * @version $Id$
 */
public class Logger {

  /**
   * Set the default hierarchy to which the <code>Logger</code> should send its
   * logging output.
   *
   * @param hierarchy The logging defaultHierarchy.
   */
  public static void setHierarchy(String hierarchy) {
    // there is no need for that anymore
  }

  /** The Constant instances. */
  private static final Map<String, org.slf4j.Logger> instances = new HashMap<>();

  /**
   * Gets the logger.
   *
   * @return the logger
   */
  private static synchronized org.slf4j.Logger getLogger() {
    final StackTraceElement[] stacktrace = Thread.currentThread().getStackTrace();

    int i;
    for (i = 2; i < stacktrace.length; i++) {
      if (!stacktrace[i].getClassName().equals(Logger.class.getName())) {
        break;
      }
    }

    final String className = stacktrace[i].getClassName();

    org.slf4j.Logger logger = instances.get(className);
    if (logger != null) {
      return logger;
    }

    logger = org.slf4j.LoggerFactory.getLogger(className);
    instances.put(className, logger);

    return logger;
  }

  /**
   * Prepare the message for printing it as string.
   * <p>
   * Mainly introduce because the <code>message</code> might be <code>null</code>.
   *
   * @param message the message
   * @return the string
   */
  private static String prepareMessage(Object message) {
    if (null == message) {
      return "no message given";
    }
    return message.toString();
  }

  /**
   * Test, if the trace log level is enabled.
   *
   * @return boolean <code>true</code>, if tracing output is enabled
   *         <code>false</code> otherwise.
   */
  public static boolean isTraceEnabled() {
    final org.slf4j.Logger logger = getLogger();
    return logger.isTraceEnabled();
  }

  /**
   * Test, if the trace log level is enabled for a given hierarchy.
   *
   * @param hierarchy requested log hierarchy
   * @return boolean <code>true</code>, if tracing output is enabled
   *         <code>false</code> otherwise.
   */
  public static boolean isTraceEnabled(String hierarchy) {
    final org.slf4j.Logger logger = getLogger();
    return logger.isTraceEnabled();
  }

  /**
   * Trace a message.
   *
   * @param message The message to trace.
   */
  public static void trace(Object message) {
    final org.slf4j.Logger logger = getLogger();
    logger.trace(prepareMessage(message));
  }

  /**
   * Test, if the debug log level is enabled.
   *
   * @return boolean <code>true</code>, if debug output is enabled
   *         <code>false</code> otherwise.
   */
  public static boolean isDebugEnabled() {
    final org.slf4j.Logger logger = getLogger();
    return logger.isDebugEnabled();
  }

  /**
   * Test, if the debug log level is enabled for a given hierarchy.
   *
   * @param hierarchy requested log hierarchy
   * @return boolean <code>true</code>, if debug output is enabled
   *         <code>false</code> otherwise.
   */
  public static boolean isDebugEnabled(String hierarchy) {
    final org.slf4j.Logger logger = getLogger();
    return logger.isDebugEnabled();
  }

  /**
   * Log a debug message.
   *
   * @param message The message to log.
   */
  public static void debug(Object message) {
    final org.slf4j.Logger logger = getLogger();
    logger.debug(prepareMessage(message));
  }

  /**
   * Log an info message.
   *
   * @param message The message to log.
   */
  public static void info(Object message) {
    final org.slf4j.Logger logger = getLogger();
    logger.info(prepareMessage(message));
  }

  /**
   * Log a warning message.
   *
   * @param message The message to log.
   */
  public static void warn(Object message) {
    final org.slf4j.Logger logger = getLogger();
    logger.warn(prepareMessage(message));
  }

  /**
   * Log a warning message.
   *
   * @param message The message to log.
   * @param t       An exception that may be the cause of the warning.
   */
  public static void warn(Object message, Throwable t) {
    final org.slf4j.Logger logger = getLogger();
    logger.warn(prepareMessage(message), t);
  }

  /**
   * Log an error message.
   *
   * @param message The message to log.
   */
  public static void error(Object message) {
    final org.slf4j.Logger logger = getLogger();
    logger.error(prepareMessage(message));
  }

  /**
   * Log an error message.
   *
   * @param message The message to log.
   * @param t       An exception that may be the cause of the error.
   */
  public static void error(Object message, Throwable t) {
    final org.slf4j.Logger logger = getLogger();
    logger.error(prepareMessage(message), t);
  }

  /**
   * Log a fatal error message.
   *
   * @param message The message to log.
   */
  public static void fatal(Object message) {
    error(message);
  }

  /**
   * Log a fatal error message.
   *
   * @param message The message to log.
   * @param t       An exception that may be the cause of the error.
   */
  public static void fatal(Object message, Throwable t) {
    error(message, t);
  }
}