package org.apache.archiva.checksum;
   
   /*
    * 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.
   */
  
  
  import org.apache.commons.io.FilenameUtils;
  
  import java.nio.file.Path;
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.List;
  import java.util.Map;
  import java.util.Set;
  
  /**
   * Enumeration of available ChecksumAlgorithm techniques.
   *
   * Each algorithm represents a message digest algorithm and has a unique type.
   * The type string may be used in the hash files (FreeBSD and OpenSSL add the type to the hash file)
   *
   * There are multiple file extensions. The first one is considered the default extension.
   *
   */
  public enum ChecksumAlgorithm {
      MD5("MD5", "MD5", "md5"),
      SHA1("SHA-1", "SHA1", "sha1", "sha128", "sha-128"),
      SHA256("SHA-256", "SHA256", "sha256", "sha2", "sha-256"),
      SHA384("SHA-384", "SHA384", "sha384", "sha3", "sha-384"),
      SHA512("SHA-512", "SHA512", "sha512", "sha5", "sha-512"),
      ASC("ASC", "ASC", "asc");
  
      public static ChecksumAlgorithm getByExtension( Path file )
      {
          String ext = FilenameUtils.getExtension( file.getFileName().toString() ).toLowerCase();
          if (extensionMap.containsKey(ext)) {
              return extensionMap.get(ext);
          }
          throw new IllegalArgumentException( "Filename " + file.getFileName() + " has no valid extension." );
      }
  
      private static final Map<String, ChecksumAlgorithm> extensionMap = new HashMap<>(  );
  
      static {
          for (ChecksumAlgorithm alg : ChecksumAlgorithm.values()) {
              for (String extString : alg.getExt())
              {
                  extensionMap.put( extString.toLowerCase(), alg );
              }
          }
      }
  
      public static Set<String> getAllExtensions() {
          return extensionMap.keySet();
      }
  
      /**
       * The MessageDigest algorithm for this hash.
       */
      private final String algorithm;
  
      /**
       * The file extensions for this ChecksumAlgorithm.
       */
      private final List<String> ext;
  
      /**
       * The checksum type, the key that you see in checksum files.
       */
      private final String type;
  
      /**
       * Construct a ChecksumAlgorithm
       * 
       * @param algorithm the MessageDigest algorithm
       * @param type a unique identifier for the type
       * @param ext the list of file extensions
       */
      private ChecksumAlgorithm( String algorithm, String type, String... ext )
      {
         this.algorithm = algorithm;
         this.ext = Arrays.asList( ext );
         this.type = type;
 
     }
 
     /**
      * Returns the message digest algorithm identifier
      * @return
      */
     public String getAlgorithm()
     {
         return algorithm;
     }
 
     /**
      * Returns the list of extensions
      * @return
      */
     public List<String> getExt()
     {
         return ext;
     }
 
     /**
      * Returns the checksum identifier
      * @return
      */
     public String getType()
     {
         return type;
     }
 
     /**
      * Returns the default extension of the current algorithm
      * @return
      */
     public String getDefaultExtension() {
         return ext.get(0);
     }
     
     
 }