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package ee.tlu.htk.dippler.utils;

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

/**
 *
 * @author pjotr
 */
public class GenerateHash {
    public static String generateMD5(String input) {
        try {
            MessageDigest md = MessageDigest.getInstance("MD5");
            byte[] digest = md.digest(input.getBytes());
            String result = hexEncode(digest);
            // Just a check in case we get less than 32 chars
            while(result.length() < 32) {
                result = "0" + result;
            }
            return result;
        } catch (NoSuchAlgorithmException e) {
            //throw new RuntimeException(e);
            System.err.println(e);
        }
        return null;
    }

    public static String generateSHA1(String input) {
        try {
            MessageDigest md = MessageDigest.getInstance("SHA-1");
            byte[] digest = md.digest(input.getBytes());
            return hexEncode(digest);
        } catch (NoSuchAlgorithmException e) {
            //throw new RuntimeException(e);
            System.err.println(e);
        }
        return null;
    }

    /**
     * The byte[] returned by MessageDigest does not have a nice
     * textual representation, so some form of encoding is usually performed.
     *
     * This implementation follows the example of David Flanagan's book
     * "Java In A Nutshell", and converts a byte array into a String
     * of hex characters.
     *
     * Another popular alternative is to use a "Base64" encoding.
     */
    static private String hexEncode(byte[] aInput) {
        StringBuilder result = new StringBuilder();
        char[] digits = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};
        for (int idx = 0; idx < aInput.length; ++idx) {
            byte b = aInput[idx];
            result.append(digits[(b & 0xf0) >> 4]);
            result.append(digits[b & 0x0f]);
        }
        return result.toString();
    }
}