content: /*
   * This library is part of OpenCms -
   * the Open Source Content Management System
   *
   * Copyright (c) Alkacon Software GmbH & Co. KG (https://www.alkacon.com)
   *
   * This library is free software; you can redistribute it and/or
   * modify it under the m_terms of the GNU Lesser General Public
   * License as published by the Free Software Foundation; either
   * version 2.1 of the License, or (at your option) any later version.
   *
   * This library is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
   * Lesser General Public License for more details.
   *
   * For further information about Alkacon Software GmbH & Co. KG, please see the
   * company website: https://www.alkacon.com
   *
   * For further information about OpenCms, please see the
   * project website: https://www.opencms.org
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with this library; if not, write to the Free Software
   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
   */
  
  package org.opencms.search.documents;
  
  import org.opencms.i18n.CmsEncoder;
  import org.opencms.main.OpenCms;
  import org.opencms.search.CmsSearchIndex;
  import org.opencms.search.CmsSearchParameters;
  import org.opencms.search.fields.CmsLuceneFieldConfiguration;
  
  import java.io.IOException;
  import java.io.StringReader;
  import java.util.Iterator;
  
  import org.apache.lucene.analysis.Analyzer;
  import org.apache.lucene.analysis.TokenStream;
  import org.apache.lucene.document.Document;
  import org.apache.lucene.search.Query;
  import org.apache.lucene.search.highlight.Highlighter;
  import org.apache.lucene.search.highlight.InvalidTokenOffsetsException;
  import org.apache.lucene.search.highlight.QueryTermScorer;
  
  /**
   * Default highlighter implementation used for generation of search excerpts.<p>
   *
   * @since 6.0.0
   */
  public class CmsTermHighlighterHtml implements I_CmsTermHighlighter {
  
      /** Separator for the search excerpt fragments. */
      private static final String EXCERPT_FRAGMENT_SEPARATOR = " ... ";
  
      /** Fragments required in excerpt. */
      private static final int EXCERPT_REQUIRED_FRAGMENTS = 5;
  
      /**
       * @see org.opencms.search.documents.I_CmsTermHighlighter#getExcerpt(org.apache.lucene.document.Document, org.opencms.search.CmsSearchIndex, org.opencms.search.CmsSearchParameters, org.apache.lucene.search.Query, org.apache.lucene.analysis.Analyzer)
       */
      public String getExcerpt(
          Document doc,
          CmsSearchIndex index,
          CmsSearchParameters params,
          Query query,
          Analyzer analyzer) throws IOException, InvalidTokenOffsetsException {
  
          if ((doc == null) || (index == null) || (params == null) || (analyzer == null) || (query == null)) {
              return null;
          }
          if (!(index.getFieldConfiguration() instanceof CmsLuceneFieldConfiguration)) {
              // also return null if the field configuration is not a lucene field configuration
              return null;
          }
          Highlighter highlighter = null;
          CmsLuceneFieldConfiguration conf = (CmsLuceneFieldConfiguration)index.getFieldConfiguration();
          Iterator<String> excerptFieldNames = conf.getExcerptFieldNames().iterator();
          StringBuffer excerptBuffer = new StringBuffer();
          while (excerptFieldNames.hasNext()) {
              String fieldName = excerptFieldNames.next();
              boolean createExcerpt = !params.isExcerptOnlySearchedFields() || params.getFields().contains(fieldName);
              if (createExcerpt && (doc.getField(fieldName) != null)) {
                  // only generate field excerpt if the field is available in the document
                  String text = doc.getField(fieldName).stringValue();
                  // make sure all XML in the text is escaped, otherwise excerpt HTML output may be garbled
                  text = CmsEncoder.escapeXml(text);
  
                  TokenStream stream = analyzer.tokenStream(fieldName, new StringReader(text));
  
                  if (params.isExcerptOnlySearchedFields()) {
                      // highlight the search query only in the matching fields
                      highlighter = new Highlighter(new QueryTermScorer(query, fieldName));
                  } else {
                      // highlight search query in all fields
                      if (highlighter == null) {
                          highlighter = new Highlighter(new QueryTermScorer(query));
                      }
                  }
                  String fragment = highlighter.getBestFragments(
                      stream,
                      text,
                      EXCERPT_REQUIRED_FRAGMENTS,
                      EXCERPT_FRAGMENT_SEPARATOR);
  
                  // kill all unwanted chars in the excerpt
                  fragment = fragment.replace('\t', ' ');
                  fragment = fragment.replace('\n', ' ');
                  fragment = fragment.replace('\r', ' ');
                  fragment = fragment.replace('\f', ' ');
  
                  if (excerptBuffer.length() > 0) {
                      // this is not the first fragment
                      excerptBuffer.append(EXCERPT_FRAGMENT_SEPARATOR);
                  }
                  excerptBuffer.append(fragment);
              }
          }
  
          String result = null;
          if (excerptBuffer.length() > 0) {
              result = excerptBuffer.toString();
          }
  
          int maxLength = OpenCms.getSearchManager().getMaxExcerptLength();
          if ((result != null) && (result.length() > maxLength)) {
              result = result.substring(0, maxLength);
          }
  
          return result;
      }
  }