package org.apache.maven.wagon.shared.http;
   
   /*
    * 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.IOUtils;
  import org.apache.maven.wagon.TransferFailedException;
  import org.jsoup.Jsoup;
  import org.jsoup.nodes.Document;
  import org.jsoup.nodes.Element;
  import org.jsoup.select.Elements;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.UnsupportedEncodingException;
  import java.net.URI;
  import java.net.URISyntaxException;
  import java.net.URLDecoder;
  import java.util.ArrayList;
  import java.util.HashSet;
  import java.util.List;
  import java.util.Set;
  import java.util.regex.Pattern;
  
  /**
   * Html File List Parser.
   */
  public class HtmlFileListParser
  {
      // Apache Fancy Index Sort Headers
      private static final Pattern APACHE_INDEX_SKIP = Pattern.compile( "\\?[CDMNS]=.*" );
  
      // URLs with excessive paths.
      private static final Pattern URLS_WITH_PATHS = Pattern.compile( "/[^/]*/" );
  
      // URLs that to a parent directory.
      private static final Pattern URLS_TO_PARENT = Pattern.compile( "\\.\\./" );
  
      // mailto urls
      private static final Pattern MAILTO_URLS = Pattern.compile( "mailto:.*" );
  
      private static final Pattern[] SKIPS =
          new Pattern[]{ APACHE_INDEX_SKIP, URLS_WITH_PATHS, URLS_TO_PARENT, MAILTO_URLS };
  
      /**
       * Fetches a raw HTML from a provided InputStream, parses it, and returns the file list.
       *
       * @param stream the input stream.
       * @return the file list.
       * @throws TransferFailedException if there was a problem fetching the raw html.
       */
      public static List<String> parseFileList( String baseurl, InputStream stream )
          throws TransferFailedException
      {
          try
          {
              URI baseURI = new URI( baseurl );
              // to make debugging easier, start with a string. This is assuming UTF-8, which might not be a safe
              // assumption.
              String content = IOUtils.toString( stream, "utf-8" );
              Document doc = Jsoup.parse( content, baseurl );
              Elements links = doc.select( "a[href]" );
              Set<String> results = new HashSet<String>();
              for ( Element link : links )
              {
                  /*
                   * The abs:href loses directories, so we deal with absolute paths ourselves below in cleanLink
                   */
                  String target = link.attr( "href" );
                  if ( target != null )
                  {
                      String clean = cleanLink( baseURI, target );
                      if ( isAcceptableLink( clean ) )
                      {
                          results.add( clean );
                      }
                  }
  
              }
  
              return new ArrayList<String>( results );
          }
          catch ( URISyntaxException e )
         {
             throw new TransferFailedException( "Unable to parse as base URI: " + baseurl, e );
         }
         catch ( IOException e )
         {
             throw new TransferFailedException( "I/O error reading HTML listing of artifacts: " + e.getMessage(), e );
         }
     }
 
     private static String cleanLink( URI baseURI, String link )
     {
         if ( link == null || link.length() == 0 )
         {
             return "";
         }
 
         String ret = link;
 
         try
         {
             URI linkuri = new URI( ret );
             if ( link.startsWith( "/" ) )
             {
                 linkuri = baseURI.resolve( linkuri );
             }
             URI relativeURI = baseURI.relativize( linkuri ).normalize();
             ret = relativeURI.toASCIIString();
             if ( ret.startsWith( baseURI.getPath() ) )
             {
                 ret = ret.substring( baseURI.getPath().length() );
             }
 
             ret = URLDecoder.decode( ret, "UTF-8" );
         }
         catch ( URISyntaxException e )
         {
             // ignore
         }
         catch ( UnsupportedEncodingException e )
         {
             // ignore
         }
 
         return ret;
     }
 
     private static boolean isAcceptableLink( String link )
     {
         if ( link == null || link.length() == 0 )
         {
             return false;
         }
 
         for ( Pattern pattern : SKIPS )
         {
             if ( pattern.matcher( link ).find() )
             {
                 return false;
             }
         }
 
         return true;
     }
 
 }