/*
    * 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.shared.jar.identification.hash;
  
  import javax.inject.Named;
  import javax.inject.Singleton;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.util.List;
  import java.util.jar.JarEntry;
  
  import org.apache.commons.codec.digest.DigestUtils;
  import org.apache.maven.shared.jar.JarAnalyzer;
  import org.apache.maven.shared.jar.JarData;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Analyzer that calculates the hash code for the entire file. Can be used to detect an exact copy of the file's class
   * data. Useful to see thru a recompile, recompression, or timestamp change.
   */
  @Singleton
  @Named("bytecode")
  public class JarBytecodeHashAnalyzer implements JarHashAnalyzer {
      private final Logger logger = LoggerFactory.getLogger(getClass());
  
      public String computeHash(JarAnalyzer jarAnalyzer) {
          JarData jarData = jarAnalyzer.getJarData();
  
          String result = jarData.getBytecodeHash();
          if (result == null) {
              List<JarEntry> entries = jarAnalyzer.getClassEntries();
  
              try {
                  for (JarEntry entry : entries) {
                      try (InputStream is = jarAnalyzer.getEntryInputStream(entry)) {
                          result = DigestUtils.sha1Hex(is);
                      }
                  }
                  jarData.setBytecodeHash(result);
              } catch (IOException e) {
                  logger.warn("Unable to calculate the hashcode.", e);
              }
          }
          return result;
      }
  }