package com.vci.common.utility;

import java.net.InetAddress;
import java.net.UnknownHostException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.util.Random;

import com.vci.common.log.ServerWithLog4j;

/**
 * <p>Title: </p>
 * <p>Description: create guid which length is 36</p>
 */
public final class RandomGUID36 extends Object {

	public String valueBeforeMD5 = "";
	public String valueAfterMD5 = "";
	private static Random myRand;
	private static SecureRandom mySecureRand;
	private static String s_id;
	private static final int PAD_BELOW = 0x10;
	private static final int TWO_BYTES = 0xFF;
	   
	static 
	{
		mySecureRand = new SecureRandom();
		long secureInitializer = mySecureRand.nextLong();
		myRand = new Random(secureInitializer);
		try 
		{
	         s_id = InetAddress.getLocalHost().toString();
		} 
		catch (UnknownHostException e) 
		{
	         e.printStackTrace();
		}
	}

	public RandomGUID36() 
	{
	      getRandomGUID(false);
	}
	
	public RandomGUID36(boolean secure) 
	{
		getRandomGUID(secure);
	}
	private void getRandomGUID(boolean secure) 
	{
		MessageDigest md5 = null;
		StringBuffer sbValueBeforeMD5 = new StringBuffer(128);
		try 
		{
	         md5 = MessageDigest.getInstance("MD5");
		} 
		catch (NoSuchAlgorithmException e) 
		{
			ServerWithLog4j.logger.error("Error: " + e);
		}
		try {
			long time = System.currentTimeMillis();
			long rand = 0;
			if (secure) 
			{
				rand = mySecureRand.nextLong();
			} 
			else 
			{
				rand = myRand.nextLong();
			}
			sbValueBeforeMD5.append(s_id);
			sbValueBeforeMD5.append(":");
			sbValueBeforeMD5.append(Long.toString(time));
			sbValueBeforeMD5.append(":");
			sbValueBeforeMD5.append(Long.toString(rand));
			valueBeforeMD5 = sbValueBeforeMD5.toString();
			md5.update(valueBeforeMD5.getBytes());
			byte[] array = md5.digest();
			StringBuffer sb = new StringBuffer(32);
			for (int j = 0; j < array.length; ++j) 
			{	
				int b = array[j] & TWO_BYTES;
	            if (b < PAD_BELOW)
	               sb.append('0');
	            sb.append(Integer.toHexString(b));
			}
			valueAfterMD5 = sb.toString();
		} 
		catch (Exception e) 
		{
			ServerWithLog4j.logger.error("Error:" + e);
		}
	}
	public String toString() {
		String raw = valueAfterMD5.toUpperCase();
		StringBuffer sb = new StringBuffer(64);
		sb.append(raw.substring(0, 8));
		sb.append("-");
		sb.append(raw.substring(8, 12));
		sb.append("-");
		sb.append(raw.substring(12, 16));
		sb.append("-");
		sb.append(raw.substring(16, 20));
		sb.append("-");	
		sb.append(raw.substring(20));
		return sb.toString();
	}
}