/*
* Copyright 2010 Srikanth Reddy Lingala  
* 
* Licensed under the Apache License, Version 2.0 (the "License"); 
* you may not use this file except in compliance with the License. 
* You may obtain a copy of the License at 
* 
* http://www.apache.org/licenses/LICENSE-2.0 
* 
* Unless required by applicable law or agreed to in writing, 
* software distributed under the License is distributed on an "AS IS" BASIS, 
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
* See the License for the specific language governing permissions and 
* limitations under the License. 
*/

package com.zip4j.crypto.PBKDF2;

/*
 * Source referred from Matthias Gartner's PKCS#5 implementation - 
 * see http://rtner.de/software/PBKDF2.html 
 */

class BinTools
{
    public static final String hex = "0123456789ABCDEF";
    
    public static String bin2hex(final byte[] b)
    {
        if (b == null)
        {
            return "";
        }
        StringBuffer sb = new StringBuffer(2 * b.length);
        for (int i = 0; i < b.length; i++)
        {
            int v = (256 + b[i]) % 256;
            sb.append(hex.charAt((v / 16) & 15));
            sb.append(hex.charAt((v % 16) & 15));
        }
        return sb.toString();
    }
    
    public static byte[] hex2bin(final String s)
    {
        String m = s;
        if (s == null)
        {
            // Allow empty input string.
            m = "";
        }
        else if (s.length() % 2 != 0)
        {
            // Assume leading zero for odd string length
            m = "0" + s;
        }
        byte r[] = new byte[m.length() / 2];
        for (int i = 0, n = 0; i < m.length(); n++)
        {
            char h = m.charAt(i++);
            char l = m.charAt(i++);
            r[n] = (byte) (hex2bin(h) * 16 + hex2bin(l));
        }
        return r;
    }
    
    public static int hex2bin(char c)
    {
        if (c >= '0' && c <= '9')
        {
            return (c - '0');
        }
        if (c >= 'A' && c <= 'F')
        {
            return (c - 'A' + 10);
        }
        if (c >= 'a' && c <= 'f')
        {
            return (c - 'a' + 10);
        }
        throw new IllegalArgumentException(
                "Input string may only contain hex digits, but found '" + c
                        + "'");
    }
}
