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.archiva.common.utils.FileUtils;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.io.FileNotFoundException;
  import java.io.IOException;
  import java.nio.charset.Charset;
  import java.nio.file.Files;
  import java.nio.file.Path;
  import java.nio.file.StandardOpenOption;
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.List;
  import java.util.regex.Matcher;
  import java.util.regex.Pattern;
  
  import static org.apache.archiva.checksum.ChecksumValidationException.ValidationError.BAD_CHECKSUM_FILE;
  import static org.apache.archiva.checksum.ChecksumValidationException.ValidationError.BAD_CHECKSUM_FILE_REF;
  
  /**
   * ChecksummedFile
   * <p>Terminology:</p>
   * <dl>
   * <dt>Checksum File</dt>
   * <dd>The file that contains the previously calculated checksum value for the reference file.
   * This is a text file with the extension ".sha1" or ".md5", and contains a single entry
   * consisting of an optional reference filename, and a checksum string.
   * </dd>
   * <dt>Reference File</dt>
   * <dd>The file that is being referenced in the checksum file.</dd>
   * </dl>
   */
  public class ChecksummedFile
  {
  
      private static Charset FILE_ENCODING = Charset.forName( "UTF-8" );
  
      private final Logger log = LoggerFactory.getLogger( ChecksummedFile.class );
  
      private static final Pattern METADATA_PATTERN = Pattern.compile( "maven-metadata-\\S*.xml" );
  
      private final Path referenceFile;
  
      /**
       * Construct a ChecksummedFile object.
       *
       * @param referenceFile
       */
      public ChecksummedFile( final Path referenceFile )
      {
          this.referenceFile = referenceFile;
      }
  
  
      public static ChecksumReference getFromChecksumFile( Path checksumFile )
      {
          ChecksumAlgorithm alg = ChecksumAlgorithm.getByExtension( checksumFile );
          ChecksummedFilemmedFile.html#ChecksummedFile">ChecksummedFile file = new ChecksummedFile( getReferenceFile( checksumFile ) );
          return new ChecksumReference( file, alg, checksumFile );
      }
  
      private static Path getReferenceFile( Path checksumFile )
      {
          String fileName = checksumFile.getFileName( ).toString( );
          return checksumFile.resolveSibling( fileName.substring( 0, fileName.lastIndexOf( '.' ) ) );
      }
  
      /**
       * Calculate the checksum based on a given checksum.
       *
       * @param checksumAlgorithm the algorithm to use.
       * @return the checksum string for the file.
       * @throws IOException if unable to calculate the checksum.
       */
      public String calculateChecksum( ChecksumAlgorithm checksumAlgorithm )
          throws IOException
      {
  
         Checksumksum.html#Checksum">Checksum checksum = new Checksum( checksumAlgorithm );
         ChecksumUtil.update(checksum, referenceFile );
         return checksum.getChecksum( );
     }
 
     /**
      * Writes a checksum file for the referenceFile.
      *
      * @param checksumAlgorithm the hash to use.
      * @return the checksum File that was created.
      * @throws IOException if there was a problem either reading the referenceFile, or writing the checksum file.
      */
     public Path writeFile(ChecksumAlgorithm checksumAlgorithm )
         throws IOException
     {
         Path checksumFile = referenceFile.resolveSibling( referenceFile.getFileName( ) + "." + checksumAlgorithm.getDefaultExtension() );
         Files.deleteIfExists( checksumFile );
         String checksum = calculateChecksum( checksumAlgorithm );
         Files.write( checksumFile, //
             ( checksum + "  " + referenceFile.getFileName( ).toString( ) ).getBytes( ), //
             StandardOpenOption.CREATE_NEW );
         return checksumFile;
     }
 
     /**
      * Get the checksum file for the reference file and hash.
      * It returns a file for the given checksum, if one exists with one of the possible extensions.
      * If it does not exist, a default path will be returned.
      *
      * @param checksumAlgorithm the hash that we are interested in.
      * @return the checksum file to return
      */
     public Path getChecksumFile( ChecksumAlgorithm checksumAlgorithm )
     {
         for ( String ext : checksumAlgorithm.getExt( ) )
         {
             Path file = referenceFile.resolveSibling( referenceFile.getFileName( ) + "." + checksumAlgorithm.getExt( ) );
             if ( Files.exists( file ) )
             {
                 return file;
             }
         }
         return referenceFile.resolveSibling( referenceFile.getFileName( ) + "." + checksumAlgorithm.getDefaultExtension() );
     }
 
     /**
      * <p>
      * Given a checksum file, check to see if the file it represents is valid according to the checksum.
      * </p>
      * <p>
      * NOTE: Only supports single file checksums of type MD5 or SHA1.
      * </p>
      *
      * @param algorithm the algorithms to check for.
      * @return true if the checksum is valid for the file it represents. or if the checksum file does not exist.
      * @throws IOException if the reading of the checksumFile or the file it refers to fails.
      */
     public boolean isValidChecksum( ChecksumAlgorithm algorithm) throws ChecksumValidationException
     {
         return isValidChecksum( algorithm, false );
     }
     public boolean isValidChecksum( ChecksumAlgorithm algorithm, boolean throwExceptions )
         throws ChecksumValidationException
     {
         return isValidChecksums( Arrays.asList( algorithm ), throwExceptions );
     }
 
     /**
      * Of any checksum files present, validate that the reference file conforms
      * the to the checksum.
      *
      * @param algorithms the algorithms to check for.
      * @return true if the checksums report that the the reference file is valid, false if invalid.
      */
     public boolean isValidChecksums( List<ChecksumAlgorithm> algorithms) throws ChecksumValidationException
     {
         return isValidChecksums( algorithms, false );
     }
 
     /**
      * Checks if the checksum files are valid for the referenced file.
      * It tries to find a checksum file for each algorithm in the same directory as the referenceFile.
      * The method returns true, if at least one checksum file exists for one of the given algorithms
      * and all existing checksum files are valid.
      *
      * This method throws only exceptions, if throwExceptions is true. Otherwise false will be returned instead.
      *
      * It verifies only the existing checksum files. If the checksum file for a particular algorithm does not exist,
      * but others exist and are valid, it will return true.
      *
      * @param algorithms The algorithms to verify
      * @param throwExceptions If true, exceptions will be thrown, otherwise false will be returned, if a exception occurred.
      * @return True, if it is valid for all existing checksum files, otherwise false.
      * @throws ChecksumValidationException
      */
     public boolean isValidChecksums( List<ChecksumAlgorithm> algorithms, boolean throwExceptions) throws ChecksumValidationException
     {
 
         List<Checksum> checksums;
         // Parse file once, for all checksums.
         try
         {
             checksums = ChecksumUtil.initializeChecksums( referenceFile, algorithms );
         }
         catch (IOException e )
         {
             log.warn( "Unable to update checksum:{}", e.getMessage( ) );
             if (throwExceptions) {
                 if (e instanceof FileNotFoundException) {
                     throw new ChecksumValidationException(ChecksumValidationException.ValidationError.FILE_NOT_FOUND, e);
                 } else {
                     throw new ChecksumValidationException(ChecksumValidationException.ValidationError.READ_ERROR, e);
                 }
             } else {
                 return false;
             }
         }
 
         boolean valid = true;
         boolean fileExists = false;
 
         // No file exists -> return false
         // if at least one file exists:
         // -> all existing files must be valid
 
         // check the checksum files
         try
         {
 
             for ( Checksum checksum : checksums )
             {
                 ChecksumAlgorithm checksumAlgorithm = checksum.getAlgorithm( );
                 Path checksumFile = getChecksumFile( checksumAlgorithm );
 
                 if (Files.exists(checksumFile)) {
                     fileExists = true;
                     String expectedChecksum = parseChecksum(checksumFile, checksumAlgorithm, referenceFile.getFileName().toString(), FILE_ENCODING);
 
                     valid &= checksum.compare(expectedChecksum);
                 }
             }
         }
         catch ( ChecksumValidationException e )
         {
             log.warn( "Unable to read / parse checksum: {}", e.getMessage( ) );
             if (throwExceptions) {
                 throw e;
             } else
             {
                 return false;
             }
         }
 
         return fileExists && valid;
     }
 
     public Path getReferenceFile( )
     {
         return referenceFile;
     }
 
 
 
     public UpdateStatusList fixChecksum(ChecksumAlgorithm algorithm) {
         return fixChecksums( Arrays.asList(algorithm) );
     }
 
     /**
      * Writes a checksum file, if it does not exist or if it exists and has a different
      * checksum value.
      *
      * @param algorithms the hashes to check for.
      * @return true if checksums were created successfully.
      */
     public UpdateStatusList fixChecksums( List<ChecksumAlgorithm> algorithms )
     {
         UpdateStatusList result = UpdateStatusList.INITIALIZE(algorithms);
         List<Checksum> checksums;
 
 
         try
         {
             // Parse file once, for all checksums.
             checksums = ChecksumUtil.initializeChecksums(getReferenceFile(), algorithms);
         }
         catch (IOException e )
         {
             log.warn( e.getMessage( ), e );
             result.setTotalError(e);
             return result;
         }
         // Any checksums?
         if ( checksums.isEmpty( ) )
         {
             // No checksum objects, no checksum files, default to is valid.
             return result;
         }
 
         boolean valid = true;
 
         // check the hash files
         for ( Checksum checksum : checksums )
         {
             ChecksumAlgorithm checksumAlgorithm = checksum.getAlgorithm( );
             try
             {
                 Path checksumFile = getChecksumFile( checksumAlgorithm );
                 if ( Files.exists( checksumFile ) )
                 {
                     String expectedChecksum;
                     try
                     {
                         expectedChecksum = parseChecksum( checksumFile, checksumAlgorithm, referenceFile.getFileName( ).toString( ), FILE_ENCODING );
                     } catch (ChecksumValidationException ex) {
                         expectedChecksum = "";
                     }
 
                     if ( !checksum.compare( expectedChecksum ) )
                     {
                         // overwrite checksum file
                         writeChecksumFile( checksumFile, FILE_ENCODING, checksum.getChecksum( ) );
                         result.setStatus(checksumAlgorithm,UpdateStatus.UPDATED);
                     }
                 }
                 else
                 {
                     writeChecksumFile( checksumFile, FILE_ENCODING, checksum.getChecksum( ) );
                     result.setStatus(checksumAlgorithm, UpdateStatus.CREATED);
                 }
             }
             catch ( ChecksumValidationException e )
             {
                 log.warn( e.getMessage( ), e );
                 result.setErrorStatus(checksumAlgorithm, e);
             }
         }
 
         return result;
 
     }
 
     private void writeChecksumFile( Path checksumFile, Charset encoding, String checksumHex )
     {
         FileUtils.writeStringToFile( checksumFile, FILE_ENCODING, checksumHex + "  " + referenceFile.getFileName( ).toString( ) );
     }
 
     private boolean isValidChecksumPattern( String filename, String path )
     {
         // check if it is a remote metadata file
 
         Matcher m = METADATA_PATTERN.matcher( path );
         if ( m.matches( ) )
         {
             return filename.endsWith( path ) || ( "-".equals( filename ) ) || filename.endsWith( "maven-metadata.xml" );
         }
 
         return filename.endsWith( path ) || ( "-".equals( filename ) );
     }
 
     /**
      * Parse a checksum string.
      * <p>
      * Validate the expected path, and expected checksum algorithm, then return
      * the trimmed checksum hex string.
      * </p>
      *
      * @param checksumFile The file where the checksum is stored
      * @param checksumAlgorithm The checksum algorithm to check
      * @param fileName The filename of the reference file
      * @return
      * @throws IOException
      */
     public String parseChecksum( Path checksumFile, ChecksumAlgorithm checksumAlgorithm, String fileName, Charset encoding )
         throws ChecksumValidationException
     {
         ChecksumFileContent fc = parseChecksumFile( checksumFile, checksumAlgorithm, encoding );
         if ( fc.isFormatMatch() && !isValidChecksumPattern( fc.getFileReference( ), fileName ) )
         {
             throw new ChecksumValidationException(BAD_CHECKSUM_FILE_REF,
                 "The file reference '" + fc.getFileReference( ) + "' in the checksum file does not match expected file: '" + fileName + "'" );
         } else if (!fc.isFormatMatch()) {
             throw new ChecksumValidationException( BAD_CHECKSUM_FILE, "The checksum file content could not be parsed: "+checksumFile );
         }
         return fc.getChecksum( );
 
     }
     public ChecksumFileContent parseChecksumFile( Path checksumFile, ChecksumAlgorithm checksumAlgorithm, Charset encoding )
     {
         ChecksumFileContentileContent.html#ChecksumFileContent">ChecksumFileContent fc = new ChecksumFileContent( );
         String rawChecksumString = FileUtils.readFileToString( checksumFile, encoding );
         String trimmedChecksum = rawChecksumString.replace( '\n', ' ' ).trim( );
 
         // Free-BSD / openssl
         String regex = checksumAlgorithm.getType( ) + "\\s*\\(([^)]*)\\)\\s*=\\s*([a-fA-F0-9]+)";
         Matcher m = Pattern.compile( regex ).matcher( trimmedChecksum );
         if ( m.matches( ) )
         {
             fc.setFileReference( m.group( 1 ) );
             fc.setChecksum( m.group( 2 ) );
             fc.setFormatMatch( true );
         }
         else
         {
             // GNU tools
             m = Pattern.compile( "([a-fA-F0-9]+)\\s+\\*?(.+)" ).matcher( trimmedChecksum );
             if ( m.matches( ) )
             {
                 fc.setFileReference( m.group( 2 ) );
                 fc.setChecksum( m.group( 1 ) );
                 fc.setFormatMatch( true );
             }
             else
             {
                 fc.setFileReference( "" );
                 fc.setChecksum( trimmedChecksum );
                 fc.setFormatMatch( false );
             }
         }
         return fc;
     }
 }