/*
 * Copyright (C) 2007 Jonathan Craven <http://jonathan.craven.fr>
 *
 * 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 2
 * 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, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */ 
 
package fr.craven.util;

import java.io.FileNotFoundException;
import java.io.PrintStream;

/**
 * <p>Redirects stderr and stdout to a file to catch hard-to-find error messages, especially
 * on Windows systems.  Not a replacement for proper logging!</p>
 *
 * <h4>Example usage</h4>
 *
 * <p>In your main class, insert the following:</p>
 *
 * <blockquote>
 * <tt>
  <pre>
  static {
    StdRedirect.redirect(System.getProperty("user.home") + File.separator + "myLogFile.log");
  }

  </pre>
  </tt>
  </blockquote>
 *
 * <h5>Copyright &copy; 2007 Jonathan Craven <a href="http://jonathan.craven.fr">http://jonathan.craven.fr</a></h5>
 *
 * @author Jonathan Craven
 * 
 */
public final class StdRedirect extends PrintStream {
    
    private static PrintStream instance;
    
    private StdRedirect(String filename) throws FileNotFoundException {
        super(filename);
    }
    
    /**
     * @see fr.craven.util.StdRedirect
     * @throws IllegalStateException if invoked more than once.
     */
    public static void redirect(String filename) {
        if (instance != null) 
            throw new IllegalStateException("You shouldn't be calling redirect more than once, it's wacky");
        try {
            instance = new StdRedirect(filename);
            System.setErr(instance);
            System.setOut(instance);
        } catch (FileNotFoundException ex) {
            ex.printStackTrace();
            throw new RuntimeException(ex);
        }
        return;
    }
    
}