/*
 * Copyright 2007-2010 Sun Microsystems, Inc.
 *
 * This file is part of Project Darkstar Server.
 *
 * Project Darkstar Server is free software: you can redistribute it
 * and/or modify it under the terms of the GNU General Public License
 * version 2 as published by the Free Software Foundation and
 * distributed hereunder to you.
 *
 * Project Darkstar Server 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/>.
 *
 * --
 */

package com.sun.sgs.impl.auth;

import java.io.FileOutputStream;
import java.security.MessageDigest;


/**
 * This is a simple utility program used to create the password files that
 * are consumed by <code>NamePasswordAuthenticator</code>. The password
 * files consist of one entry per line, where each entry has a name, some
 * whitespace, a SHA-256 hashed password encoded via a call to
 * <code>NamePasswordAuthenticator.encodeBytes</code>, and finally a newline.
 */
public final class PasswordFileEditor
{
    /**
     * This class should not be instantiated
     */
    private PasswordFileEditor() {
    
    }

    /**
     * Main-line for this utility. This utility takes three arguments on
     * the command line. The first argument is the file to update, the second
     * argument is the user name, and the third argument is that user's
     * password.
     *
     * @param args the arguments for this utility
     *
     * @throws Exception if anything fails
     */
    public static void main(String [] args) throws Exception {
        if (args.length != 3) {
            System.out.println("Usage: password_file name password");
            return;
        }

        // make sure we can hash and encode the password
        byte [] pass = MessageDigest.getInstance("SHA-256").
            digest(args[2].getBytes("UTF-8"));
        byte [] encodedPass = NamePasswordAuthenticator.encodeBytes(pass);

        FileOutputStream out = null;
        try {
            // open the file and append the new entry
            out = new FileOutputStream(args[0], true);
            out.write(args[1].getBytes("UTF-8"));
            out.write("\t".getBytes("UTF-8"));
            out.write(encodedPass);
            out.write("\n".getBytes("UTF-8"));
        } finally {
            out.close();
        }
    }

}