/**
   * Fetches the attachment content from the repository. Content is flat text that can be used for
   * indexing/searching or display
   *
   * @param attachmentName Name of the attachment.
   * @param version The version of the attachment.
   * @return the content of the Attachment as a String.
   */
  protected String getAttachmentContent(String attachmentName, int version) {
    AttachmentManager mgr = m_engine.getAttachmentManager();

    try {
      Attachment att = mgr.getAttachmentInfo(attachmentName, version);
      // FIXME: Find out why sometimes att is null
      if (att != null) {
        return getAttachmentContent(att);
      }
    } catch (ProviderException e) {
      log.error("Attachment cannot be loaded", e);
    }
    // Something was wrong, no result is returned.
    return null;
  }
  /** {@inheritDoc} */
  public void initialize(WikiEngine engine, Properties props)
      throws NoRequiredPropertyException, IOException {
    m_engine = engine;

    m_luceneDirectory = engine.getWorkDir() + File.separator + LUCENE_DIR;

    int initialDelay =
        TextUtil.getIntegerProperty(props, PROP_LUCENE_INITIALDELAY, LuceneUpdater.INITIAL_DELAY);
    int indexDelay =
        TextUtil.getIntegerProperty(props, PROP_LUCENE_INDEXDELAY, LuceneUpdater.INDEX_DELAY);

    m_analyzerClass = TextUtil.getStringProperty(props, PROP_LUCENE_ANALYZER, m_analyzerClass);
    // FIXME: Just to be simple for now, we will do full reindex
    // only if no files are in lucene directory.

    File dir = new File(m_luceneDirectory);

    log.info("Lucene enabled, cache will be in: " + dir.getAbsolutePath());

    try {
      if (!dir.exists()) {
        dir.mkdirs();
      }

      if (!dir.exists() || !dir.canWrite() || !dir.canRead()) {
        log.error("Cannot write to Lucene directory, disabling Lucene: " + dir.getAbsolutePath());
        throw new IOException("Invalid Lucene directory.");
      }

      String[] filelist = dir.list();

      if (filelist == null) {
        throw new IOException(
            "Invalid Lucene directory: cannot produce listing: " + dir.getAbsolutePath());
      }
    } catch (IOException e) {
      log.error("Problem while creating Lucene index - not using Lucene.", e);
    }

    // Start the Lucene update thread, which waits first
    // for a little while before starting to go through
    // the Lucene "pages that need updating".
    LuceneUpdater updater = new LuceneUpdater(m_engine, this, initialDelay, indexDelay);
    updater.start();
  }
  /**
   * Adds a page-text pair to the lucene update queue. Safe to call always
   *
   * @param page WikiPage to add to the update queue.
   */
  public void reindexPage(WikiPage page) {
    if (page != null) {
      String text;

      // TODO: Think if this was better done in the thread itself?

      if (page instanceof Attachment) {
        text = getAttachmentContent((Attachment) page);
      } else {
        text = m_engine.getPureText(page);
      }

      if (text != null) {
        // Add work item to m_updates queue.
        Object[] pair = new Object[2];
        pair[0] = page;
        pair[1] = text;
        m_updates.add(pair);
        log.debug("Scheduling page " + page.getName() + " for index update");
      }
    }
  }
  /**
   * @param att Attachment to get content for. Filename extension is used to determine the type of
   *     the attachment.
   * @return String representing the content of the file. FIXME This is a very simple implementation
   *     of some text-based attachment, mainly used for testing. This should be replaced /moved to
   *     Attachment search providers or some other 'pluggable' wat to search attachments
   */
  protected String getAttachmentContent(Attachment att) {
    AttachmentManager mgr = m_engine.getAttachmentManager();
    // FIXME: Add attachment plugin structure

    String filename = att.getFileName();

    boolean searchSuffix = false;
    for (String suffix : SEARCHABLE_FILE_SUFFIXES) {
      if (filename.endsWith(suffix)) {
        searchSuffix = true;
      }
    }

    if (searchSuffix) {
      InputStream attStream;

      try {
        attStream = mgr.getAttachmentStream(att);

        StringWriter sout = new StringWriter();
        FileUtil.copyContents(new InputStreamReader(attStream), sout);

        attStream.close();
        sout.close();

        return sout.toString();
      } catch (ProviderException e) {
        log.error("Attachment cannot be loaded", e);
        return null;
      } catch (IOException e) {
        log.error("Attachment cannot be loaded", e);
        return null;
      }
    }

    return null;
  }
  /**
   * Searches pages using a particular combination of flags.
   *
   * @param query The query to perform in Lucene query language
   * @param flags A set of flags
   * @return A Collection of SearchResult instances
   * @throws ProviderException if there is a problem with the backend
   */
  public Collection findPages(String query, int flags) throws ProviderException {
    IndexSearcher searcher = null;
    ArrayList<SearchResult> list = null;
    Highlighter highlighter = null;

    try {
      String[] queryfields = {
        LUCENE_PAGE_CONTENTS, LUCENE_PAGE_NAME, LUCENE_AUTHOR, LUCENE_ATTACHMENTS
      };
      QueryParser qp =
          new MultiFieldQueryParser(Version.LUCENE_36, queryfields, getLuceneAnalyzer());

      // QueryParser qp = new QueryParser( LUCENE_PAGE_CONTENTS, getLuceneAnalyzer() );
      Query luceneQuery = qp.parse(query);

      if ((flags & FLAG_CONTEXTS) != 0) {
        highlighter =
            new Highlighter(
                new SimpleHTMLFormatter("<span class=\"searchmatch\">", "</span>"),
                new SimpleHTMLEncoder(),
                new QueryScorer(luceneQuery));
      }

      try {
        File dir = new File(m_luceneDirectory);
        Directory luceneDir = new SimpleFSDirectory(dir, null);
        IndexReader reader = IndexReader.open(luceneDir);
        searcher = new IndexSearcher(reader);
      } catch (Exception ex) {
        log.info("Lucene not yet ready; indexing not started", ex);
        return null;
      }

      ScoreDoc[] hits = searcher.search(luceneQuery, MAX_SEARCH_HITS).scoreDocs;

      list = new ArrayList<SearchResult>(hits.length);
      for (int curr = 0; curr < hits.length; curr++) {
        int docID = hits[curr].doc;
        Document doc = searcher.doc(docID);
        String pageName = doc.get(LUCENE_ID);
        WikiPage page = m_engine.getPage(pageName, WikiPageProvider.LATEST_VERSION);

        if (page != null) {
          if (page instanceof Attachment) {
            // Currently attachments don't look nice on the search-results page
            // When the search-results are cleaned up this can be enabled again.
          }

          int score = (int) (hits[curr].score * 100);

          // Get highlighted search contexts
          String text = doc.get(LUCENE_PAGE_CONTENTS);

          String[] fragments = new String[0];
          if (text != null && highlighter != null) {
            TokenStream tokenStream =
                getLuceneAnalyzer().tokenStream(LUCENE_PAGE_CONTENTS, new StringReader(text));
            fragments = highlighter.getBestFragments(tokenStream, text, MAX_FRAGMENTS);
          }

          SearchResult result = new SearchResultImpl(page, score, fragments);
          list.add(result);
        } else {
          log.error(
              "Lucene found a result page '"
                  + pageName
                  + "' that could not be loaded, removing from Lucene cache");
          pageRemoved(new WikiPage(m_engine, pageName));
        }
      }
    } catch (IOException e) {
      log.error("Failed during lucene search", e);
    } catch (ParseException e) {
      log.info("Broken query; cannot parse query ", e);

      throw new ProviderException(
          "You have entered a query Lucene cannot process: " + e.getMessage());
    } catch (InvalidTokenOffsetsException e) {
      log.error("Tokens are incompatible with provided text ", e);
    } finally {
      if (searcher != null) {
        try {
          searcher.close();
        } catch (IOException e) {
          log.error(e);
        }
      }
    }

    return list;
  }
  /**
   * Indexes page using the given IndexWriter.
   *
   * @param page WikiPage
   * @param text Page text to index
   * @param writer The Lucene IndexWriter to use for indexing
   * @return the created index Document
   * @throws IOException If there's an indexing problem
   */
  protected Document luceneIndexPage(WikiPage page, String text, IndexWriter writer)
      throws IOException {
    if (log.isDebugEnabled()) log.debug("Indexing " + page.getName() + "...");

    // make a new, empty document
    Document doc = new Document();

    if (text == null) return doc;

    // Raw name is the keyword we'll use to refer to this document for updates.
    Field field = new Field(LUCENE_ID, page.getName(), Field.Store.YES, Field.Index.NOT_ANALYZED);
    doc.add(field);

    // Body text.  It is stored in the doc for search contexts.
    field =
        new Field(
            LUCENE_PAGE_CONTENTS, text, Field.Store.YES, Field.Index.ANALYZED, Field.TermVector.NO);
    doc.add(field);

    // Allow searching by page name. Both beautified and raw
    String unTokenizedTitle =
        StringUtils.replaceChars(
            page.getName(), MarkupParser.PUNCTUATION_CHARS_ALLOWED, c_punctuationSpaces);

    field =
        new Field(
            LUCENE_PAGE_NAME,
            TextUtil.beautifyString(page.getName()) + " " + unTokenizedTitle,
            Field.Store.YES,
            Field.Index.ANALYZED,
            Field.TermVector.NO);
    doc.add(field);

    // Allow searching by authorname

    if (page.getAuthor() != null) {
      field =
          new Field(
              LUCENE_AUTHOR,
              page.getAuthor(),
              Field.Store.YES,
              Field.Index.ANALYZED,
              Field.TermVector.NO);
      doc.add(field);
    }

    // Now add the names of the attachments of this page
    try {
      Collection attachments = m_engine.getAttachmentManager().listAttachments(page);
      String attachmentNames = "";

      for (Iterator it = attachments.iterator(); it.hasNext(); ) {
        Attachment att = (Attachment) it.next();
        attachmentNames += att.getName() + ";";
      }
      field =
          new Field(
              LUCENE_ATTACHMENTS,
              attachmentNames,
              Field.Store.YES,
              Field.Index.ANALYZED,
              Field.TermVector.NO);
      doc.add(field);

    } catch (ProviderException e) {
      // Unable to read attachments
      log.error("Failed to get attachments for page", e);
    }
    writer.addDocument(doc);

    return doc;
  }
  /**
   * Performs a full Lucene reindex, if necessary.
   *
   * @throws IOException If there's a problem during indexing
   */
  protected void doFullLuceneReindex() throws IOException {
    File dir = new File(m_luceneDirectory);

    String[] filelist = dir.list();

    if (filelist == null) {
      throw new IOException(
          "Invalid Lucene directory: cannot produce listing: " + dir.getAbsolutePath());
    }

    try {
      if (filelist.length == 0) {
        //
        //  No files? Reindex!
        //
        Date start = new Date();
        IndexWriter writer = null;

        log.info("Starting Lucene reindexing, this can take a couple minutes...");

        Directory luceneDir = new SimpleFSDirectory(dir, null);

        try {
          writer = getIndexWriter(luceneDir);
          Collection allPages = m_engine.getPageManager().getAllPages();

          for (Iterator iterator = allPages.iterator(); iterator.hasNext(); ) {
            WikiPage page = (WikiPage) iterator.next();

            try {
              String text =
                  m_engine
                      .getPageManager()
                      .getPageText(page.getName(), WikiProvider.LATEST_VERSION);
              luceneIndexPage(page, text, writer);
            } catch (IOException e) {
              log.warn("Unable to index page " + page.getName() + ", continuing to next ", e);
            }
          }

          Collection allAttachments = m_engine.getAttachmentManager().getAllAttachments();
          for (Iterator iterator = allAttachments.iterator(); iterator.hasNext(); ) {
            Attachment att = (Attachment) iterator.next();

            try {
              String text = getAttachmentContent(att.getName(), WikiProvider.LATEST_VERSION);
              luceneIndexPage(att, text, writer);
            } catch (IOException e) {
              log.warn("Unable to index attachment " + att.getName() + ", continuing to next", e);
            }
          }

        } finally {
          close(writer);
        }

        Date end = new Date();
        log.info(
            "Full Lucene index finished in "
                + (end.getTime() - start.getTime())
                + " milliseconds.");
      } else {
        log.info("Files found in Lucene directory, not reindexing.");
      }
    } catch (NoClassDefFoundError e) {
      log.info("Lucene libraries do not exist - not using Lucene.");
    } catch (IOException e) {
      log.error("Problem while creating Lucene index - not using Lucene.", e);
    } catch (ProviderException e) {
      log.error("Problem reading pages while creating Lucene index (JSPWiki won't start.)", e);
      throw new IllegalArgumentException("unable to create Lucene index");
    } catch (Exception e) {
      log.error("Unable to start lucene", e);
    }
  }