/*
 * 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.eclipse.aether.internal.impl.checksum;

import java.nio.ByteBuffer;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

import org.eclipse.aether.spi.connector.checksum.ChecksumAlgorithm;
import org.eclipse.aether.spi.connector.checksum.ChecksumAlgorithmFactory;
import org.eclipse.aether.spi.connector.checksum.ChecksumAlgorithmFactorySupport;
import org.eclipse.aether.util.StringDigestUtil;

/**
 * Support class to implement {@link ChecksumAlgorithmFactory} based on Java {@link MessageDigest}.
 *
 * @since 1.8.0
 */
public abstract class MessageDigestChecksumAlgorithmFactorySupport extends ChecksumAlgorithmFactorySupport {
    public MessageDigestChecksumAlgorithmFactorySupport(String name, String extension) {
        super(name, extension);
    }

    @Override
    public ChecksumAlgorithm getAlgorithm() {
        try {
            MessageDigest messageDigest = MessageDigest.getInstance(getName());
            return new ChecksumAlgorithm() {
                @Override
                public void update(final ByteBuffer input) {
                    messageDigest.update(input);
                }

                @Override
                public String checksum() {
                    return StringDigestUtil.toHexString(messageDigest.digest());
                }
            };
        } catch (NoSuchAlgorithmException e) {
            throw new IllegalStateException(
                    "MessageDigest algorithm " + getName() + " not supported, but is required by resolver.", e);
        }
    }
}
