/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 ~ 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.sling.graphql.core.hash;

import java.nio.charset.StandardCharsets;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

import org.apache.sling.graphql.api.SlingGraphQLException;
import org.jetbrains.annotations.NotNull;

public class SHA256Hasher {

    private SHA256Hasher() {
    }

    @NotNull
    public static String getHash(@NotNull String message) {
        StringBuilder buffer = new StringBuilder();
        try {
            MessageDigest digest = MessageDigest.getInstance("SHA-256");
            byte[] hash = digest.digest(message.getBytes(StandardCharsets.UTF_8));

            for (byte b : hash) {
                String hex = Integer.toHexString(0xff & b);
                if (hex.length() == 1) {
                    buffer.append('0');
                }
                buffer.append(hex);
            }
        } catch (NoSuchAlgorithmException e) {
            throw new SlingGraphQLException("Failed hashing message.", e);
        }
        return buffer.toString();
    }
}