/*-
 * ============LICENSE_START=======================================================
 * ONAP - SO
 * ================================================================================
 * Copyright (C) 2017 AT&T Intellectual Property. All rights reserved.
 * ================================================================================
 * 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.
 * ============LICENSE_END=========================================================
 */

package org.openecomp.mso.bpmn.common.util;


import java.security.GeneralSecurityException;
import java.security.NoSuchAlgorithmException;

import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;

//Need to add BPM error handler

/**
 * CryptoUtils adapted from RTTP client.
 *
 */
public class CryptoUtils {

    public static final String AES = "AES";

    /**
    * encrypt a value and generate a keyfile
     * if the keyfile is not found then a new one is created
    * @throws GeneralSecurityException
     * @throws IOException
     */
    public static String encrypt(String value, String keyString) throws GeneralSecurityException
    {
        SecretKeySpec sks = getSecretKeySpec(keyString);
        Cipher cipher = Cipher.getInstance(CryptoUtils.AES);
        cipher.init(Cipher.ENCRYPT_MODE, sks, cipher.getParameters());
        byte[] encrypted = cipher.doFinal(value.getBytes());
        return byteArrayToHexString(encrypted);
    }

    /**
    * decrypt a value
     * @throws GeneralSecurityException
     * @throws IOException
     */
    public static String decrypt(String message, String keyString) throws GeneralSecurityException
    {
        SecretKeySpec sks = getSecretKeySpec(keyString);
        Cipher cipher = Cipher.getInstance(CryptoUtils.AES);
        cipher.init(Cipher.DECRYPT_MODE, sks);
        byte[] decrypted = cipher.doFinal(hexStringToByteArray(message));
        return new String(decrypted);
    }

    private static SecretKeySpec getSecretKeySpec(String keyString) throws NoSuchAlgorithmException
    {
        byte [] key = hexStringToByteArray(keyString);
        SecretKeySpec sks = new SecretKeySpec(key, CryptoUtils.AES);
        return sks;
    }


    private static String byteArrayToHexString(byte[] b){
        StringBuffer sb = new StringBuffer(b.length * 2);
        for (int i = 0; i < b.length; i++){
            int v = b[i] & 0xff;
            if (v < 16) {
            	sb.append('0');
            }
            sb.append(Integer.toHexString(v));
    }
        return sb.toString().toUpperCase();
    }

    private static byte[] hexStringToByteArray(String s) {
        byte[] b = new byte[s.length() / 2];
        for (int i = 0; i < b.length; i++){
            int index = i * 2;
            int v = Integer.parseInt(s.substring(index, index + 2), 16);
            b[i] = (byte)v;
        }
        return b;
    }

    /**
     * Not Used...
     *
    * Call Rttp utility jar to encrypt pwd
    * @param clearPassword
    * @return
    * @throws GeneralSecurityException
     * @throws Exception
    *
    public static String encryptRttpPwd(String clearPassword) throws GeneralSecurityException {
        try {
            return RttpBasicAuth.encrypt(clearPassword);
        } catch (Exception e) {
            // wrap generic exception
            throw new GeneralSecurityException(e);
        }
    }
    */
}