/*
 * Computoser is a music-composition algorithm and a website to present the results
 * Copyright (C) 2012-2014  Bozhidar Bozhanov
 *
 * Computoser is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * Computoser 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with Computoser.  If not, see <http://www.gnu.org/licenses/>.
 */

package com.music.util;

import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;

import org.apache.commons.codec.binary.Hex;
import org.apache.commons.lang3.StringUtils;

public final class SecurityUtils {

    private static final String HMAC_SHA1_ALGORITHM = "HmacSHA1";

    /**
     * Calculates a HmacSHA1 value
     *
     * @param data
     * @param key
     * @return HmacSHA1
     */
    public static String hmac(String data, String key) {
        try {
            // get an hmac_sha1 key from the raw key bytes
            SecretKeySpec signingKey = new SecretKeySpec(key.getBytes(), HMAC_SHA1_ALGORITHM);
            Mac mac = Mac.getInstance(HMAC_SHA1_ALGORITHM);
            mac.init(signingKey);

            // compute the hmac on input data bytes
            byte[] rawHmac = mac.doFinal(data.getBytes());

            String result = new String(Hex.encodeHex(rawHmac));
            return result.toUpperCase();
        } catch (Exception ex) {
            throw new RuntimeException("Problem with calculating hmac", ex);
        }
    }

    public static void main(String[] args) {
        System.out.println(hmac(StringUtils.leftPad("5", 10, '0'), "zonUgkO8FxaPbVfESWZhfzCB"));
    }
}
