/*
* The Apache Software License, Version 1.1
*
*
* Copyright (c) 2003 The Apache Software Foundation.  All rights 
* reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer. 
*
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in
*    the documentation and/or other materials provided with the
*    distribution.
*
* 3. The end-user documentation included with the redistribution,
*    if any, must include the following acknowledgment:  
*       "This product includes software developed by the
*        Apache Software Foundation (http://www.apache.org/)."
*    Alternately, this acknowledgment may appear in the software itself,
*    if and wherever such third-party acknowledgments normally appear.
*
* 4. The names "Apache" and "Apache Software Foundation" must 
*    not be used to endorse or promote products derived from this
*    software without prior written permission. For written 
*    permission, please contact apache@apache.org.
*
* 5. Products derived from this software may not be called "Apache 
*    XMLBeans", nor may "Apache" appear in their name, without prior 
*    written permission of the Apache Software Foundation.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation and was
* originally based on software copyright (c) 2000-2003 BEA Systems 
* Inc., <http://www.bea.com/>. For more information on the Apache Software
* Foundation, please see <http://www.apache.org/>.
*/

package org.apache.xmlbeans.impl.util;

import java.io.UnsupportedEncodingException;
/**
 * format validation
 *
 * This class encodes/decodes hexadecimal data
 * @author Jeffrey Rodriguez
 * @version $Id: HexBin.java,v 1.2 2003/09/24 23:31:08 ericvas Exp $
 */
public final class  HexBin {
    static private final int  BASELENGTH   = 255;
    static private final int  LOOKUPLENGTH = 16;
    static private byte [] hexNumberTable    = new byte[BASELENGTH];
    static private byte [] lookUpHexAlphabet = new byte[LOOKUPLENGTH];


    static {
        for (int i = 0; i<BASELENGTH; i++ ) {
            hexNumberTable[i] = -1;
        }
        for ( int i = '9'; i >= '0'; i--) {
            hexNumberTable[i] = (byte) (i-'0');
        }
        for ( int i = 'F'; i>= 'A'; i--) {
            hexNumberTable[i] = (byte) ( i-'A' + 10 );
        }
        for ( int i = 'f'; i>= 'a'; i--) {
           hexNumberTable[i] = (byte) ( i-'a' + 10 );
        }

        for(int i = 0; i<10; i++ )
            lookUpHexAlphabet[i] = (byte) ('0'+i );
        for(int i = 10; i<=15; i++ )
            lookUpHexAlphabet[i] = (byte) ('A'+i -10);
    }

    /**
     * byte to be tested if it is Base64 alphabet
     *
     * @param octect
     * @return
     */
    static boolean isHex(byte octect) {
        return (hexNumberTable[octect] != -1);
    }

    /**
     * Converts bytes to a hex string
     */
    static public String bytesToString(byte[] binaryData)
    {
        if (binaryData == null)
            return null;
        return new String(encode(binaryData));
    }

    /**
     * Converts a hex string to a byte array.
     */
    static public byte[] stringToBytes(String hexEncoded)
    {
        return decode(hexEncoded.getBytes());
    }

    /**
     * array of byte to encode
     *
     * @param binaryData
     * @return return encode binary array
     */
    static public byte[] encode(byte[] binaryData) {
        if (binaryData == null)
            return null;
        int lengthData   = binaryData.length;
        int lengthEncode = lengthData * 2;
        byte[] encodedData = new byte[lengthEncode];
        for( int i = 0; i<lengthData; i++ ){
            encodedData[i*2] = lookUpHexAlphabet[(binaryData[i] >> 4) & 0xf];
            encodedData[i*2+1] = lookUpHexAlphabet[ binaryData[i] & 0xf];
        }
        return encodedData;
    }

    static public byte[] decode(byte[] binaryData) {
        if (binaryData == null)
            return null;
        int lengthData   = binaryData.length;
        if (lengthData % 2 != 0)
            return null;

        int lengthDecode = lengthData / 2;
        byte[] decodedData = new byte[lengthDecode];
        for( int i = 0; i<lengthDecode; i++ ){
            if (!isHex(binaryData[i*2]) || !isHex(binaryData[i*2+1])) {
                return null;
            }
            decodedData[i] = (byte)((hexNumberTable[binaryData[i*2]] << 4) | hexNumberTable[binaryData[i*2+1]]);
        }
        return decodedData;
    }

    /**
     * Decodes Hex data into octects
     *
     * @param binaryData String containing Hex data
     * @return string containing decoded data.
     */
    public static String decode(String binaryData) {
        if (binaryData == null)
            return null;

        byte[] decoded = null;
         try {
          decoded = decode(binaryData.getBytes("utf-8"));
        }
        catch(UnsupportedEncodingException e) {
         }
        finally {
        return decoded == null ? null : new String(decoded);
        }
    }

    /**
     * Encodes octects (using utf-8) into Hex data
     *
     * @param binaryData String containing Hex data
     * @return string containing decoded data.
     */
    public static String encode(String binaryData) {
        if (binaryData == null)
            return null;

        byte[] encoded = null;
         try {
          encoded = encode(binaryData.getBytes("utf-8"));
        }
        catch(UnsupportedEncodingException e) {}
        finally {
            return encoded == null ? null : new String(encoded);
        }
    }

}