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

 Copyright (C) 2000-2005  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.engine;

import java.io.IOException;
import java.io.InputStream;

import org.apache.log4j.Logger;

/**
 * Helper class to invoke system commands via static methods.
 * 
 * @author Markus Kraetzig 
 */
public final class SysRun {
    private static final Logger log = Logger.getLogger(SysRun.class);

    /**
     * Creates a new process with an argument and returns immediately. This
     * method could for example be used to call a viewer with a file argument.
     * The viewer should be installed on the system.
     * 
     * @param command
     *            name of the executable to run
     * @param arg
     *            argument for the process to create
     * @throws IllegalArgumentException
     *             if (command == null || command.length() == 0)
     * @throws RuntimeException
     *             if an execute failed due to an IOException
     */
    public static void invoke(String command, String arg) {

        if (command == null || command.length() == 0)
            throw new IllegalArgumentException("Command was empty.");

        try {

            Process proc = Runtime.getRuntime().exec(command + " " + arg);
            handleInput(proc.getInputStream());
        } catch (IOException e) {
            throw new RuntimeException("Command \"" + command
                    + "\" with argument \"" + arg + "\" failed.\n"
                    + e.getMessage());
        }

    }

    /**
     * Deals with input of an invoked process.
     * 
     * @param is
     */
    private static void handleInput(final InputStream is) {
        new Thread(new Runnable() {
            public void run() {
                try {
                    byte[] b = new byte[8];
                    int size = 0;
                    while ((size = is.read(b)) >= 0) {
                        log.info(new String(b, 0, size));
                    }

                } catch (Throwable e) {

                }
            }
        }).start();
    }
}