package com.onaro.util.jfc;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

/**
 * Handles an exception thrown in the AWT event-dispatch thread.
 * By default exceptions are just logged.
 * AWT's <code>java.awt.EventDispatchThread</code> searches the system property
 * "<i>sun.awt.exception.handler</i>" when it catces an exception. If found it
 * will attempt to do the following:<nl>
 * <li>Load the class named by the value of that property, using the current
 * thread's context class loader,
 * <li>Instantiate that class using its zero-argument constructor,
 * <li>Find the resulting handler object's <code>public void handle</code> method,
 * which should take a single argument of type <code>Throwable</code>, and
 * <li>Invoke the handler's <code>handle</code> method, passing it the thrown
 * exception that was caught.
 * </nl>
 * If any of the first three steps fail then this the exception will simply be
 * dumped to the standard error. An exception thrown by the handler object's handle
 * will be caught, and will disable further usage of this handler.
 * <p>
 * <b>Note:</b> This method is a temporary hack to work around the absence of a
 * real API that provides the ability to replace the event-dispatch thread.
 * The magic "sun.awt.exception.handler" property will be removed in a future
 * release.
 */
public class AWTExceptionHandler {

    static Logger logger = LogManager.getLogger(AWTExceptionHandler.class);

    /**
     * Handle an uncaught exception by simply sending it to the logger.
     *
     * @param t the uncaught exception
     */
    public void handle (Throwable t) {
        logger.error("Uncaught exception in java.awt.EventDispatchThread - " + t.getMessage(), t); //$NON-NLS-1$
    }

    /**
     * Install this handler by setting the system property.
     */
    public static void install() {
        install(AWTExceptionHandler.class.getName());
    }

    /**
     * Install this handler by setting the system property.
     * @param className the name of the handler class
     */
    public static void install(String className) {
        logger.debug("Replacing current AWT exception handler (" + //$NON-NLS-1$
                System.getProperty("sun.awt.exception.handler") + //$NON-NLS-1$
                ") with " + className); //$NON-NLS-1$
        System.setProperty("sun.awt.exception.handler", className); //$NON-NLS-1$
    }
}