/*
 * Enhydra Java Application Server Project
 * 
 * The contents of this file are subject to the Enhydra Public License
 * Version 1.1 (the "License"); you may not use this file except in
 * compliance with the License. You may obtain a copy of the License on
 * the Enhydra web site ( http://www.enhydra.org/ ).
 * 
 * Software distributed under the License is distributed on an "AS IS"
 * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See 
 * the License for the specific terms governing rights and limitations
 * under the License.
 * 
 * The Initial Developer of the Enhydra Application Server is Lutris
 * Technologies, Inc. The Enhydra Application Server and portions created
 * by Lutris Technologies, Inc. are Copyright Lutris Technologies, Inc.
 * All Rights Reserved.
 * 
 * Contributor(s):
 * 
 * $Id: HexEncoder.java,v 1.15 2005/06/13 09:26:06 draganr Exp $
 */

package	com.lutris.util;
import	java.io.*;
import	java.text.*;

/**
 * Various conversion methods.
 * These methods are mostly used to convert internal java data
 * fields into byte arrays or strings for use in 8 bit ASCII fields.
 *
 * @author Mike Ward
 */
public class HexEncoder {
    /**
     * Hexadecimal characters corresponding to each half byte value.
     */
    private static final char[] HexChars = {
	'0', '1', '2', '3', '4', '5', '6', '7',
	'8', '9', 'a', 'b', 'c', 'd', 'e', 'f'
    };

    /**
     * Converts a long integer to an unsigned hexadecimal String.  Treats
     * the integer as an unsigned 64 bit value and left-pads with the
     * pad character of the caller's choice.
     * 
     * @param value The long integer to convert to a hexadecimal string.
     * @param len   The total padded length of the string.  If the number
     * 		    is larger than the padded length, then this length
     * 		    of the string will be the length of the number.
     * @param pad   The character to use for padding.
     * @return	    Unsigned hexadecimal numeric string representing 
     * 		    the specified value.
     */
    public static final String toHexString(long value, int len, char pad) {
	StringBuffer sb = new StringBuffer(Long.toHexString(value));
	int npad = len - sb.length();
	while (npad-- > 0) sb.insert(0, pad);
	return new String(sb);
    }

    /**
     * Converts an arbitrary array of bytes to ASCII hexadecimal string
     * form, with two hex characters corresponding to each byte.  The
     * length of the resultant string in characters will be twice the
     * length of the specified array of bytes.
     * 
     * @param bytes The array of bytes to convert to ASCII hex form.
     * @return	    An ASCII hexadecimal numeric string representing the
     * 		    specified array of bytes.
     */
    public static final String toHexString(byte[] bytes) {
	StringBuffer sb = new StringBuffer();
	int i;
	for (i=0; i < bytes.length; i++) {
	    sb.append(HexChars[(bytes[i] >> 4) & 0xf]);
	    sb.append(HexChars[bytes[i] & 0xf]);
	}
	return new String(sb);
    }
}