/**
 * 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.atlas.utils;


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

public class SHA256Utils{


    private static final ThreadLocal<MessageDigest> DIGESTER_FACTORY =
            new ThreadLocal<MessageDigest>() {
                @Override
                protected MessageDigest initialValue() {
                    try {
                        return MessageDigest.getInstance("SHA-256");
                    } catch (NoSuchAlgorithmException e) {
                        throw new RuntimeException(e);
                    }
                }
            };

    /**
     * Create a thread local SHA256 digester.
     */

    public static MessageDigest getDigester() {
        MessageDigest digester = DIGESTER_FACTORY.get();
        digester.reset();
        return digester;
    }

    public static String toString(byte[] hash) {
        try{
            StringBuffer hexString = new StringBuffer();

            for (int i = 0; i < hash.length; i++) {
                String hex = Integer.toHexString(0xff & hash[i]);
                if(hex.length() == 1) hexString.append('0');
                hexString.append(hex);
            }

            return hexString.toString();
        } catch(Exception ex){
            throw new RuntimeException(ex);
        }
    }


}