/*
    * 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.maven.wrapper;
  
  import java.io.InputStream;
  import java.nio.file.Files;
  import java.nio.file.Path;
  import java.security.MessageDigest;
  import java.util.Locale;
  
  /**
   * @author Rafael Winterhalter
   */
  public class HashAlgorithmVerifier implements Verifier {
  
      @Override
      public void verify(Path file, String property, String algorithm, String expectedSum) throws Exception {
          MessageDigest digest = MessageDigest.getInstance(algorithm);
          try (InputStream inputStream = Files.newInputStream(file)) {
              byte[] buffer = new byte[1024 * 8];
              int length;
              while ((length = inputStream.read(buffer)) != -1) {
                  digest.update(buffer, 0, length);
              }
          }
          byte[] hash = digest.digest();
          StringBuilder actualSum = new StringBuilder(hash.length * 2);
          for (byte aByte : hash) {
              actualSum.append(String.format("%02x", aByte));
          }
          if (expectedSum.contentEquals(actualSum)) {
              Logger.info(String.format(
                      Locale.ROOT, "Validated %s hash for %s to be equal (%s)", algorithm, file, expectedSum));
          } else {
              throw new RuntimeException(String.format(
                      Locale.ROOT,
                      "Failed to validate Maven distribution %s, your Maven distribution "
                              + "might be compromised. If you updated your Maven version, you need to "
                              + "update the specified %s property.",
                      algorithm,
                      property));
          }
      }
  }