/*
 Copyright (C) 2002-2007 MySQL AB

 This program is free software; you can redistribute it and/or modify
 it under the terms of version 2 of the GNU General Public License as 
 published by the Free Software Foundation.

 There are special exceptions to the terms and conditions of the GPL 
 as it is applied to this software. View the full text of the 
 exception in file EXCEPTIONS-CONNECTOR-J in the directory of this 
 software distribution.

 This program 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, write to the Free Software
 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA



 */
package com.mysql.jdbc;

import java.io.ObjectInputStream;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.TimeZone;

/**
 * Various utility methods for the driver.
 * 
 * @author Mark Matthews
 */
public class Util {

	protected static Method systemNanoTimeMethod;
	    
	private static boolean isColdFusion = false;

	static {
		try {
			systemNanoTimeMethod = System.class.getMethod("nanoTime", null);
		} catch (SecurityException e) {
			systemNanoTimeMethod = null;
		} catch (NoSuchMethodException e) {
			systemNanoTimeMethod = null;
		}
		
		//
		// Detect the ColdFusion MX environment
		// 
		// Unfortunately, no easy-to-discern classes are available
		// to our classloader to check...
		//
		
		String loadedFrom = stackTraceToString(new Throwable());
		
		if (loadedFrom != null) {
			isColdFusion = loadedFrom.indexOf("coldfusion") != -1;
		} else {
			isColdFusion = false;
		}
	}
	
	public static boolean isColdFusion() {
		return isColdFusion;
	}
	
	protected static boolean nanoTimeAvailable() {
		return systemNanoTimeMethod != null;
	}
	
	// cache this ourselves, as the method call is statically-synchronized in all but JDK6!
	
	private static final TimeZone DEFAULT_TIMEZONE = TimeZone.getDefault();
	
	static final TimeZone getDefaultTimeZone() {
		return (TimeZone)DEFAULT_TIMEZONE.clone();
	}
	
	class RandStructcture {
		long maxValue;

		double maxValueDbl;

		long seed1;

		long seed2;
	}

	
	private static Util enclosingInstance = new Util();

	// Right from Monty's code
	static String newCrypt(String password, String seed) {
		byte b;
		double d;

		if ((password == null) || (password.length() == 0)) {
			return password;
		}

		long[] pw = newHash(seed);
		long[] msg = newHash(password);
		long max = 0x3fffffffL;
		long seed1 = (pw[0] ^ msg[0]) % max;
		long seed2 = (pw[1] ^ msg[1]) % max;
		char[] chars = new char[seed.length()];

		for (int i = 0; i < seed.length(); i++) {
			seed1 = ((seed1 * 3) + seed2) % max;
			seed2 = (seed1 + seed2 + 33) % max;
			d = (double) seed1 / (double) max;
			b = (byte) java.lang.Math.floor((d * 31) + 64);
			chars[i] = (char) b;
		}

		seed1 = ((seed1 * 3) + seed2) % max;
		seed2 = (seed1 + seed2 + 33) % max;
		d = (double) seed1 / (double) max;
		b = (byte) java.lang.Math.floor(d * 31);

		for (int i = 0; i < seed.length(); i++) {
			chars[i] ^= (char) b;
		}

		return new String(chars);
	}

	static long[] newHash(String password) {
		long nr = 1345345333L;
		long add = 7;
		long nr2 = 0x12345671L;
		long tmp;

		for (int i = 0; i < password.length(); ++i) {
			if ((password.charAt(i) == ' ') || (password.charAt(i) == '\t')) {
				continue; // skip spaces
			}

			tmp = (0xff & password.charAt(i));
			nr ^= ((((nr & 63) + add) * tmp) + (nr << 8));
			nr2 += ((nr2 << 8) ^ nr);
			add += tmp;
		}

		long[] result = new long[2];
		result[0] = nr & 0x7fffffffL;
		result[1] = nr2 & 0x7fffffffL;

		return result;
	}

	static String oldCrypt(String password, String seed) {
		long hp;
		long hm;
		long s1;
		long s2;
		long max = 0x01FFFFFF;
		double d;
		byte b;

		if ((password == null) || (password.length() == 0)) {
			return password;
		}

		hp = oldHash(seed);
		hm = oldHash(password);

		long nr = hp ^ hm;
		nr %= max;
		s1 = nr;
		s2 = nr / 2;

		char[] chars = new char[seed.length()];

		for (int i = 0; i < seed.length(); i++) {
			s1 = ((s1 * 3) + s2) % max;
			s2 = (s1 + s2 + 33) % max;
			d = (double) s1 / max;
			b = (byte) java.lang.Math.floor((d * 31) + 64);
			chars[i] = (char) b;
		}

		return new String(chars);
	}

	static long oldHash(String password) {
		long nr = 1345345333;
		long nr2 = 7;
		long tmp;

		for (int i = 0; i < password.length(); i++) {
			if ((password.charAt(i) == ' ') || (password.charAt(i) == '\t')) {
				continue;
			}

			tmp = password.charAt(i);
			nr ^= ((((nr & 63) + nr2) * tmp) + (nr << 8));
			nr2 += tmp;
		}

		return nr & ((1L << 31) - 1L);
	}

	private static RandStructcture randomInit(long seed1, long seed2) {
		RandStructcture randStruct = enclosingInstance.new RandStructcture();

		randStruct.maxValue = 0x3FFFFFFFL;
		randStruct.maxValueDbl = randStruct.maxValue;
		randStruct.seed1 = seed1 % randStruct.maxValue;
		randStruct.seed2 = seed2 % randStruct.maxValue;

		return randStruct;
	}

	/**
	 * Given a ResultSet and an index into the columns of that ResultSet, read
	 * binary data from the column which represents a serialized object, and
	 * re-create the object.
	 * 
	 * @param resultSet
	 *            the ResultSet to use.
	 * @param index
	 *            an index into the ResultSet.
	 * @return the object if it can be de-serialized
	 * @throws Exception
	 *             if an error occurs
	 */
	public static Object readObject(java.sql.ResultSet resultSet, int index)
			throws Exception {
		ObjectInputStream objIn = new ObjectInputStream(resultSet
				.getBinaryStream(index));
		Object obj = objIn.readObject();
		objIn.close();

		return obj;
	}

	private static double rnd(RandStructcture randStruct) {
		randStruct.seed1 = ((randStruct.seed1 * 3) + randStruct.seed2)
				% randStruct.maxValue;
		randStruct.seed2 = (randStruct.seed1 + randStruct.seed2 + 33)
				% randStruct.maxValue;

		return ((randStruct.seed1) / randStruct.maxValueDbl);
	}

	/**
	 * DOCUMENT ME!
	 * 
	 * @param message
	 *            DOCUMENT ME!
	 * @param password
	 *            DOCUMENT ME!
	 * 
	 * @return DOCUMENT ME!
	 */
	public static String scramble(String message, String password) {
		long[] hashPass;
		long[] hashMessage;
		byte[] to = new byte[8];
		String val = ""; //$NON-NLS-1$

		message = message.substring(0, 8);

		if ((password != null) && (password.length() > 0)) {
			hashPass = newHash(password);
			hashMessage = newHash(message);

			RandStructcture randStruct = randomInit(hashPass[0]
					^ hashMessage[0], hashPass[1] ^ hashMessage[1]);

			int msgPos = 0;
			int msgLength = message.length();
			int toPos = 0;

			while (msgPos++ < msgLength) {
				to[toPos++] = (byte) (Math.floor(rnd(randStruct) * 31) + 64);
			}

			/* Make it harder to break */
			byte extra = (byte) (Math.floor(rnd(randStruct) * 31));

			for (int i = 0; i < to.length; i++) {
				to[i] ^= extra;
			}

			val = new String(to);
		}

		return val;
	}

	// ~ Inner Classes
	// ----------------------------------------------------------

	/**
	 * Converts a nested exception into a nicer message
	 * 
	 * @param ex
	 *            the exception to expand into a message.
	 * 
	 * @return a message containing the exception, the message (if any), and a
	 *         stacktrace.
	 */
	public static String stackTraceToString(Throwable ex) {
		StringBuffer traceBuf = new StringBuffer();
		traceBuf.append(Messages.getString("Util.1")); //$NON-NLS-1$

		if (ex != null) {
			traceBuf.append(ex.getClass().getName());

			String message = ex.getMessage();

			if (message != null) {
				traceBuf.append(Messages.getString("Util.2")); //$NON-NLS-1$
				traceBuf.append(message);
			}

			StringWriter out = new StringWriter();

			PrintWriter printOut = new PrintWriter(out);

			ex.printStackTrace(printOut);

			traceBuf.append(Messages.getString("Util.3")); //$NON-NLS-1$
			traceBuf.append(out.toString());
		}

		traceBuf.append(Messages.getString("Util.4")); //$NON-NLS-1$

		return traceBuf.toString();
	}
	
	/**
	 * Does a network interface exist locally with the given hostname?
	 * 
	 * @param hostname the hostname (or IP address in string form) to check
	 * @return true if it exists, false if no, or unable to determine due to VM version support
	 *         of java.net.NetworkInterface
	 */
	public static boolean interfaceExists(String hostname) {
		try {
			Class networkInterfaceClass = Class.forName("java.net.NetworkInterface");
			return networkInterfaceClass.getMethod("getByName", null).invoke(networkInterfaceClass, new Object[] { hostname }) != null;
		} catch (Throwable t) {
			return false;
		}
	}

	public static long getCurrentTimeNanosOrMillis() {
		if (systemNanoTimeMethod != null) {
			try {
				return ((Long)systemNanoTimeMethod.invoke(null, null)).longValue();
			} catch (IllegalArgumentException e) {
				// ignore - fall through to currentTimeMillis()
			} catch (IllegalAccessException e) {
				// ignore - fall through to currentTimeMillis()
			} catch (InvocationTargetException e) {
				// ignore - fall through to currentTimeMillis()
			}
		}
		
		return System.currentTimeMillis();
	}
}
