/*
 Utility class duplicates System.out and System.err to a file. Useful for simple logging purposes.
 Usage:
   see main method for example usage.
 Build:
   javac DupeStream.java

 Alex Wong, Aug 2002
*/

import java.io.*;

public class DupeStream extends PrintStream {
  static PrintStream sysout;
  static PrintStream syserr;
  static OutputStream log=null;
  static boolean bothStream=true;

  public static void main(String argv[]) throws Exception {
  //invoke main method from command line with: java DupeStream <logfile>

    if (argv.length < 1) {
      System.out.println("Usage: java DupeStream <logfile>");
      System.exit(1);
    }
    System.out.println("Line 1");     //lines 1,2,3,4 goes to console(if bothStream=true)
    DupeStream.start(argv[0],true,true);     //Append output to logfile, display output to stdout/err as well.
    System.out.println("Line 2");     //lines 2,3 goes to logfile
    System.out.println("Line 3");
    DupeStream.stop();
    System.out.println("Line 4");
  }

  public DupeStream(PrintStream ps) {
  //constructor
     super(ps);
  }

  public static void start(String outfile,boolean append,boolean both) {
  //Open outfile. set sysout and syserr to outfile. if both=true, write to both file & stdout/err.

    try {
      log = new PrintStream(new BufferedOutputStream(new FileOutputStream(outfile,append)));
      sysout = System.out;
      syserr = System.err;
      bothStream=both;
      System.setOut(new DupeStream(System.out));
      System.setErr(new DupeStream(System.err));
    }
    catch (Exception e) {
      System.out.println(e.toString());
    }
  }

  public static void stop() {
  //reset sysout & syserr to prev stream. Close log file.
      if (log != null) {
        System.setOut(sysout);
        System.setErr(syserr);
        try {
          log.close();
        } catch (Exception e) {}
      }
  }

  public void write(int b) {
  //intercept the write int method in OutputStream and write to logfile first.

    if (log != null) {
      try {
        log.write(b);
      } catch (Exception e) {}
      if (bothStream) super.write(b);
    }
  }

  public void write(byte buf[],int offset,int len) {
  //intercept the write byte buf method in OutputStream and write to logfile first.

    if (log != null) {
      try {
  	    log.write(buf,offset,len);
      } catch (Exception e) {}
      if (bothStream) super.write(buf,offset,len);
    }
  }
  
  public void write(byte buf[]) {
  //intercept the write byte buf method in OutputStream and write to logfile first.

    if (log != null) {
      try {
  	    log.write(buf,0,buf.length);
      } catch (Exception e) {}
      if (bothStream) super.write(buf,0,buf.length);
    }
  }
}