/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.usergrid.utils;


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

import org.apache.commons.codec.binary.Base64;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import static org.apache.commons.lang.StringUtils.rightPad;
import static org.apache.commons.lang.StringUtils.substring;


public class AESUtils {

    private static final Logger logger = LoggerFactory.getLogger( AESUtils.class );

    private static byte[] linebreak = { };
    private static Cipher cipher;
    private static Base64 coder;


    static {
        try {
            cipher = Cipher.getInstance( "AES/ECB/PKCS5Padding", "SunJCE" );
            coder = new Base64( 32, linebreak, true );
        }
        catch ( Throwable t ) {
            logger.error( "Cipher error", t );
        }
    }


    public static synchronized String encrypt( String secret, String plainText ) {
        secret = substring( rightPad( secret, 16 ), 0, 16 );
        SecretKey key = new SecretKeySpec( secret.getBytes(), "AES" );
        try {
            cipher.init( Cipher.ENCRYPT_MODE, key );
            byte[] cipherText = cipher.doFinal( plainText.getBytes() );
            return new String( coder.encode( cipherText ) );
        }
        catch ( Exception e ) {
            logger.error( "Encryption error", e );
        }
        return null;
    }


    @SuppressWarnings("unused")
    public static synchronized String decrypt( String secret, String codedText ) {
        secret = substring( rightPad( secret, 16 ), 0, 16 );
        SecretKey key = new SecretKeySpec( secret.getBytes(), "AES" );
        byte[] encypted = coder.decode( codedText.getBytes() );
        try {
            cipher.init( Cipher.DECRYPT_MODE, key );
            byte[] decrypted = cipher.doFinal( encypted );
            return new String( decrypted );
        }
        catch ( Exception e ) {
            logger.error( "Decryption error", e );
        }
        return null;
    }
}