/*
    * 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.buildcache.hash;
  
  import java.io.IOException;
  import java.nio.file.Files;
  import java.nio.file.Path;
  import java.security.MessageDigest;
  
  /**
   * SHA
   */
  public class SHA implements Hash.Factory {
  
      private static final ThreadLocal<MessageDigest> ALGORITHM = new ThreadLocal<>();
      private static final ThreadLocal<MessageDigest> CHECKSUM = new ThreadLocal<>();
  
      private final String algorithm;
  
      SHA(String algorithm) {
          this.algorithm = algorithm;
      }
  
      @Override
      public String getAlgorithm() {
          return algorithm;
      }
  
      @Override
      public Hash.Algorithm algorithm() {
          return new SHA.Algorithm(ThreadLocalDigest.get(ALGORITHM, algorithm));
      }
  
      @Override
      public Hash.Checksum checksum(int count) {
          return new SHA.Checksum(ThreadLocalDigest.get(CHECKSUM, algorithm));
      }
  
      private static class Algorithm implements Hash.Algorithm {
  
          private final MessageDigest digest;
  
          private Algorithm(MessageDigest digest) {
              this.digest = digest;
          }
  
          @Override
          public byte[] hash(byte[] array) {
              return digest.digest(array);
          }
  
          @Override
          public byte[] hash(Path path) throws IOException {
              return hash(Files.readAllBytes(path));
          }
      }
  
      private static class Checksum implements Hash.Checksum {
  
          private final MessageDigest digest;
  
          private Checksum(MessageDigest digest) {
              this.digest = digest;
          }
  
          @Override
          public void update(byte[] hash) {
              digest.update(hash);
          }
  
          @Override
          public byte[] digest() {
              return digest.digest();
          }
      }
  }