/*
 * Copyright (C) 2000-2001  Ken McCrary
 *
 * 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
 *
 * Email: jkmccrary@yahoo.com
 */
package com.kenmccrary.jtella;

import java.io.DataOutputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.net.InetAddress;
import java.net.UnknownHostException;

import com.kenmccrary.jtella.util.Log;

/**
 *  General purpose utilities
 *
 */
public class Utilities
{
  private static short[] clientID = null;
  private static long bootTime;
  private static long counter = 0x00000000;
  
  static
  {
    bootTime = System.currentTimeMillis();
  }

  /**
   *  Generate something remotely resembling a windows guid
   *
   */
  public static short[] generateGUID()
  {
    // TODO clean this up
    short[] data = new short[16];
    int arrayIndex = 15;
    for (int i = 0; i < 8; i++)
    {
       // Mask to process one byte at a time
       long mask = 0X00000000000000FF;

       // Adjust the mask to look at the appropriate byte
       mask = mask << (8 * i);

                        
       long result = bootTime & mask;

       // Move the byte we interested in to the low order
       result = result >> (8 * i );

       // copy the processed byte
       data[arrayIndex--] = (short)result;
                        
    }

    counter++;
    arrayIndex = 7;
    for (int i = 0; i < 8; i++)
    {
      long mask = 0X00000000000000FF;
      mask = mask << (8 * i);
      long result = counter & mask;

      result = result >> (8 * i );
      data[arrayIndex--] = (short)result;
                        
    }

    return data;
    
  }  

  /**
   *  Generate something resembling a guid for this host
   *
   *
   */
  public static short[] getClientIdentifier()
  {
    if ( null == clientID )
    {
      clientID = new short[16];
      short[] address = getHostAddress();

      int addressIndex = 0;
      for (int i = 0; i < clientID.length; i++) 
      {
        if ( addressIndex == address.length ) 
        {
          addressIndex = 0;
        }

        clientID[i] = address[addressIndex++];
      }

      StringBuffer message = new StringBuffer();
      message.append("Client GUID: ");
 
      for (int i = 0; i < clientID.length; i++) 
      {
        message.append( "[" +
                        Integer.toHexString( clientID[i]) +
                        "]");
      }

      Log.getLog().logDebug(message.toString());
    }

    return clientID;
  }

  /**
   *  Returns the client guid in the form of the wrapper GUID
   *
   */
  public static GUID getClientGUID()
  {
    return new GUID(getClientIdentifier());
  }

  /**
   *  Gets the host address, works around byte[] getAddress()
   *  looking negative
   *
   *  @return address
   */
  static short[] getHostAddress()
  {
    short[] address = new short[4];
    try
    {
      InetAddress netAddress = InetAddress.getLocalHost();
      String ipAddress = netAddress.getHostAddress();


      int beginIndex = 0;
      int endIndex = ipAddress.indexOf('.');

      address[0] = (short)Integer.parseInt(ipAddress.substring(beginIndex, endIndex));

      beginIndex = endIndex + 1;
      endIndex = ipAddress.indexOf('.', beginIndex);

      address[1] = (short)Integer.parseInt(ipAddress.substring(beginIndex, endIndex));

      beginIndex = endIndex + 1;
      endIndex = ipAddress.indexOf('.', beginIndex);

      address[2] = (short)Integer.parseInt(ipAddress.substring(beginIndex, endIndex));

      beginIndex = endIndex + 1;

      address[3] = (short)Integer.parseInt(ipAddress.substring(beginIndex, ipAddress.length()));
    }
    catch (UnknownHostException e)
    {
      Log.getLog().log(e);
    }

    return address;
  }

  // test
  public static void main(String[] args)
  {
    short[] guid = Utilities.generateGUID();


    System.out.println("GUID: ");
    for ( int i = 0; i < guid.length; i++) 
    {

      System.out.println(Integer.toHexString(guid[i]));
    }
  }
}