/*
    * 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);
          }
      }
  }