/*
 This file is part of the software framework JStatCom, 
 a library for building applications for data based analysis.

 Copyright (C) 2000-2005  Alexander Benkwitz, Markus Kraetzig

 This library is free software; you can redistribute it and/or modify
 it under the terms of the GNU Lesser General Public License as
 published by the Free Software Foundation; either version 2.1 of the
 License, or (at your option) any later version.

 This library 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
 Lesser General Public License for more details.

 You should have received a copy of the GNU Lesser General Public
 License along with this library; if not, write to the Free Software
 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
 USA
 */

package com.jstatcom.io;

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.PrintStream;

import org.apache.log4j.Logger;

/**
 * Helper class to redirect stdout and stderr to a log file and/or a receiver
 * component. The redirection also keeps the original streams for
 * System.out and System.err but adds an
 * additional stream.
 * 

 * Usage Note:

 * Redirection is initiated by calling the start method.
 * Subsequent calls to start are allowed to change the file or
 * logging component. The stop method cancels redirection.
 * 
 * @author Alexander Benkwitz, Markus Kraetzig
 */
public final class RedirectOutput extends PrintStream {
    private static final Logger log = Logger.getLogger(RedirectOutput.class);

    private static RedirectReceiver redirectReceiver = null;

    private static PrintStream logFile = null;

    // Keep references of original streams.
    private static PrintStream systemOut = System.out;

    private static PrintStream systemErr = System.err;

    /**
     * SaveOutput constructor comment.
     * 
     * @param ps
     *            java.io.PrintStream
     */
    private RedirectOutput(PrintStream ps) {
        super(ps);
    }

    /**
     * Starts redirecting stdout and stderr to a log file.
     * 
     * @param fileName
     *            the name of the log file
     * @throws IllegalArgumentException
     *             if fileName == null
     */
    public static void start(String fileName) {

        if (fileName == null)
            throw new IllegalArgumentException("File argument was null.");

        // Keep standard outputs but add file redirection.
        System.setOut(new RedirectOutput(systemOut));
        System.setErr(new RedirectOutput(systemErr));

        try {
            // Create/Open logfile.
            logFile = new PrintStream(new FileOutputStream(fileName, true));
            // Start redirecting the output.
        } catch (IOException e) {
            log.error("Cannot create log file\n" + e.getMessage(), e);
        }
    }

    /**
     * Starts redirecting stdout and stderr to a logging component.
     * 
     * @param receiver
     *            the name of the receiving component
     * @throws IllegalArgumentException
     *             if receiver == null
     */
    public static void start(RedirectReceiver receiver) {

        if (receiver == null)
            throw new IllegalArgumentException("Argument was null.");

        // Keep standard outputs but add file redirection.
        System.setOut(new RedirectOutput(systemOut));
        System.setErr(new RedirectOutput(systemErr));

        redirectReceiver = receiver;

    }

    /**
     * Stops redirecting the output and restored previous settings.
     */
    public static void stop() {

        redirectReceiver = null;
        logFile = null;
        System.setOut(systemOut);
        System.setErr(systemErr);

    }

    /**
     * PrintStream overwrite.
     * 
     * @param buf
     *            byte[]
     * @param off
     *            int
     * @param len
     *            int
     */
    public void write(byte buf[], int off, int len) {
        try {
            // logFile.write(buf, off, len);
            if (redirectReceiver != null)
                redirectReceiver.append(new String(buf, off, len));
            if (logFile != null)
                logFile.write(buf, off, len);
        } catch (Throwable e) {
            log.error("Error redirecting", e);
            setError();
        }
        super.write(buf, off, len);
    }

    /**
     * PrintStream overwrite.
     * 
     * @param b
     *            int
     */
    public void write(int b) {
        try {
            // logFile.write(b);
            if (redirectReceiver != null)
                redirectReceiver.append(b + "");
            if (logFile != null)
                logFile.write(b);

        } catch (Throwable e) {
            log.error("Error redirecting", e);
            setError();
        }
        super.write(b);
    }
}