/*
    * 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.connector.basic;
  
  import java.nio.ByteBuffer;
  import java.security.MessageDigest;
  import java.security.NoSuchAlgorithmException;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.List;
  import java.util.Locale;
  import java.util.Set;
  
  import org.eclipse.aether.spi.connector.checksum.ChecksumAlgorithm;
  import org.eclipse.aether.spi.connector.checksum.ChecksumAlgorithmFactory;
  import org.eclipse.aether.spi.connector.checksum.ChecksumAlgorithmFactorySelector;
  import org.eclipse.aether.spi.connector.checksum.ChecksumAlgorithmFactorySupport;
  import org.eclipse.aether.util.StringDigestUtil;
  
  import static java.util.stream.Collectors.toList;
  
  /**
   * Test implementation of {@link ChecksumAlgorithmFactorySelector}.
   */
  public class TestChecksumAlgorithmSelector implements ChecksumAlgorithmFactorySelector {
      public static final String SHA512 = "SHA-512";
  
      public static final String SHA256 = "SHA-256";
  
      public static final String SHA1 = "SHA-1";
  
      public static final String MD5 = "MD5";
  
      public static final String TEST_CHECKSUM = "test";
  
      public static final String TEST_CHECKSUM_VALUE = "01020304";
  
      @Override
      public Set<ChecksumAlgorithmFactory> getChecksumAlgorithmFactories() {
          return Collections.emptySet(); // irrelevant
      }
  
      @Override
      public ChecksumAlgorithmFactory select(final String algorithm) {
          if (TEST_CHECKSUM.equals(algorithm)) {
              return new ChecksumAlgorithmFactorySupport(TEST_CHECKSUM, "test") {
                  @Override
                  public ChecksumAlgorithm getAlgorithm() {
                      return new ChecksumAlgorithm() {
                          @Override
                          public void update(final ByteBuffer input) {}
  
                          @Override
                          public String checksum() {
                              return TEST_CHECKSUM_VALUE;
                          }
                      };
                  }
              };
          }
          return new MessageDigestChecksumAlgorithmFactory(algorithm);
      }
  
      @Override
      public List<ChecksumAlgorithmFactory> selectList(Collection<String> algorithmNames) {
          return algorithmNames.stream().map(this::select).collect(toList());
      }
  
      @Override
      public boolean isChecksumExtension(String extension) {
          throw new RuntimeException("not implemented");
      }
  
      private static class MessageDigestChecksumAlgorithmFactory extends ChecksumAlgorithmFactorySupport {
          public MessageDigestChecksumAlgorithmFactory(String name) {
              super(name, name.replace("-", "").toLowerCase(Locale.ENGLISH));
          }
  
          @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 IllegalArgumentException("Algorithm '" + getName() + "' not supported.");
             }
         }
     }
 }