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.codehaus.plexus.util.StringUtils;

 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.getElementsByTag( "a" );

             Set<String> results = new HashSet<String>();

             for ( int lx = 0; lx < links.size(); lx++ )

             {

                 Element link = links.get( lx );

                 /*

                  * 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 ( StringUtils.isEmpty( link ) )

         {

             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 )

         {

         }

         catch ( UnsupportedEncodingException e )

         {

         }

         return ret;

     }

     private static boolean isAcceptableLink( String link )

     {

         if ( StringUtils.isEmpty( link ) )

         {

             return false;

         }

         for ( int i = 0; i < SKIPS.length; i++ )

         {

             if ( SKIPS[i].matcher( link ).find() )

             {

                 return false;

             }

         }

         return true;

     }

 }