gt: 		dialog(title, message, JOptionPane.ERROR_MESSAGE );
context: package common;
  
  import gui.MainWindow;
  import gui.SourceTab;
  
  import java.io.File;
  import java.io.FileWriter;
  import java.io.IOException;
  import java.io.PrintWriter;
  import java.text.DateFormat;
  import java.text.SimpleDateFormat;
  import java.util.Calendar;
  import java.util.Date;
  import java.util.TimeZone;
  
  import javax.swing.JOptionPane;
  
  /**
   * 
   * FOX 1 Telemetry Decoder
   * @author chris.e.thompson g0kla/ac2cz
   *
   * Copyright (C) 2015 amsat.org
   *
   * This program is free software: you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation, either version 3 of the License, or
   * (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program.  If not, see <http://www.gnu.org/licenses/>.
   *
   *
   * Save messages from the GUI to a log file for later analysis.  This is a static class and new should not be called
   *
   *
   */
  public class Log {
  
  	static private boolean echoToStdout = true; // true for debugging through eclipse because its handy.  This will never be true in production version.
  	static PrintWriter output = null;
  	public static final DateFormat fileDateFormat = new SimpleDateFormat("yyyyMMddHHmmss");
  	public static final DateFormat logDateName = new SimpleDateFormat("yyyyMMdd");
  	public static SourceTab logPanel;
  	public static String logFile = "FoxTelemDecoder";
  	public static Thread.UncaughtExceptionHandler uncaughtExHandler;
  	public static boolean showGuiDialogs = true;  // if true popup windows are shown for serious errors.  If false ALERTs are written.
  	public static boolean alertsAreFatal = true;
  	
  	/**
  	 * Initialise the logger and create a logfile with the passed name
  	 * @param file
  	 * @throws IOException 
  	 */
  	public static void init(String logFile) {
  		
  		Log.logFile = rollLog(logFile);
  		if (Config.logging) {
  			try {
  				if (!Config.logFileDirectory.equalsIgnoreCase("")) {
  					Log.logFile = Config.logFileDirectory + File.separator + Log.logFile;
  				} 
  				File aFile = new File(Log.logFile);
  				if(!aFile.exists()){
  					aFile.createNewFile();
  				}
  
  				//use buffering and append to the existing file if it is there
  				output = new PrintWriter(new FileWriter(aFile, true));
  			} catch (IOException e) {
  				System.err.println("FATAL ERROR: Cannot write log file: FoxTelemDecoder.log\n"
  						+ "Perhaps the disk is full or the directory is not writable:\n" + Config.logFileDirectory);
  
  				e.printStackTrace();
  		        Log.errorDialog("FATAL ERROR", "Cannot write log file: FoxTelemDecoder.log\n"
  		        		+ "Perhaps the disk is full or the directory is not writable:\n" + Config.logFileDirectory + "\n\n"
  		        				+ "You can reset FoxTelem by deleting the settings file (might want to back it up first):\n"
  		        				+ Config.homeDirectory+ File.separator+"FoxTelem.properties");
  		        System.exit(1);
  			}
  		}
  		uncaughtExHandler = new Thread.UncaughtExceptionHandler() {
  		    public void uncaughtException(Thread th, Throwable ex) {
  		    	
  		    	String stacktrace = makeShortTrace(ex.getStackTrace());  
  		    	
  		        Log.errorDialog("SERIOUS ERROR", "Uncaught exception.  You probablly need to restart FoxTelem:\n" + ex + "\n" + stacktrace);
  		        if (!showGuiDialogs) // this is the server
  		        	alert("Uncaught exception.  Need to clear the ALERT and restart the server:\n" + stacktrace);
  		    }
  		};
  	}
  	
  	public static String makeShortTrace(StackTraceElement[] elements) {
  		String stacktrace = "";  
          int limit = 13;
          for (int i=0; i< limit && i< elements.length; i++) {
          	stacktrace =  stacktrace + elements[i] + "\n";
          }
          if (elements.length > limit)
          	stacktrace = stacktrace + " ... " + (elements.length - limit) + " items not shown .... ";
          return stacktrace;
  	}
  	
  	public static String rollLog(String logFile) {
  		Date today = Calendar.getInstance().getTime();
  		logDateName.setTimeZone(TimeZone.getTimeZone("UTC"));
  		String reportDate = logDateName.format(today);
  		return logFile + reportDate + ".log";
  	}
  	
  	public static void alert(String message) {
  		try {
  			println("ALERT: " + message); // put as last item in the log too
  			String alertFile = Log.logFile + ".ALERT";
  			File aFile = new File(alertFile);
  			if(!aFile.exists()){
  				aFile.createNewFile();
  			}
  
  			//use buffering and append to the existing file if it is there, though this should rarely be the case for an alert
  			PrintWriter out = new PrintWriter(new FileWriter(aFile, true));
  			out.write(fileDateStamp() + message + System.getProperty("line.separator") );
  			out.flush();
  			out.close();
  			if (alertsAreFatal)
  				System.exit(9);
  		} catch (Exception e) { // catch all exceptions at this point, otherwise we can go into a loop
  			System.err.println("FATAL ERROR: Cannot write log file: FoxTelemDecoder.log\n"
  					+ "Perhaps the disk is full or the directory is not writable:\n" + Config.logFileDirectory);
  
  			e.printStackTrace();
  	        Log.errorDialog("FATAL ERROR", "Cannot write log file: FoxTelemDecoder.log\n"
  	        		+ "Perhaps the disk is full or the directory is not writable:\n" + Config.logFileDirectory + "\n\n"
  	        				+ "You can reset FoxTelem by deleting the settings file (might want to back it up first):\n"
  	        				+ Config.homeDirectory+ File.separator+"FoxTelem.properties");
  	        if (alertsAreFatal)
  	        	System.exit(1);
  		}
  	}
  	
  	public static boolean getLogging() { return Config.logging; }
  	public static void setLogging(boolean on) { Config.logging = on; }
  	public static void setStdoutEcho(boolean on) { echoToStdout = on; }
  	public static PrintWriter getWriter() { 
  		if (output != null)
  			return output;
  		else
  			return new PrintWriter(System.err);
  	}
  	
  	public static void setGUILog(SourceTab panel) {
  		logPanel = panel;
  	}
  	
  	public static void print(String s) {
  		if (Config.logging) {
  			if (output == null) init(logFile);
  			output.write(s);
  			if (logPanel != null) logPanel.log(s);
  			flush();
  		}
  		if (echoToStdout) {
  			System.out.print(s);
  		}
  
  	}
  
  	public static void println(String s) {
  		if (Config.logging) {
  			if (output == null) init("FoxTelemDecoder");
  			output.write(fileDateStamp() + s + System.getProperty("line.separator") );
  			if (logPanel != null) logPanel.log(s);
  			flush();
  		}
  		if (echoToStdout) {
  			System.out.println(s);
  		}
  
  	}
  	
  	public static int optionYNdialog(String title, String message) {
  		if (!showGuiDialogs)
  			return 1; // Default is no if a dialog is called from server
  		Object[] options = {"Yes",
          "No"};
  		int n = JOptionPane.showOptionDialog(
  				MainWindow.frame,
  				message.toString(),
  				title,
  				JOptionPane.YES_NO_OPTION, 
  			    JOptionPane.QUESTION_MESSAGE,
  			    null,
  			    options,
  			    options[1]);
  		return n;
  	}
  	
  	public static void errorDialog(String title, String message) {
  