/**
   * Return the string used to later have SOLR highlight the document with.
   *
   * @param query
   * @param literal_query
   * @param queryResults
   * @param file
   * @return
   */
  private String getHighlightQuery(
      KeywordSearchQuery query, boolean literal_query, QueryResults queryResults, Content content) {
    String highlightQueryEscaped;
    if (literal_query) {
      // literal, treat as non-regex, non-term component query
      highlightQueryEscaped = query.getQueryString();
    } else {
      // construct a Solr query using aggregated terms to get highlighting
      // the query is executed later on demand
      StringBuilder highlightQuery = new StringBuilder();

      if (queryResults.getKeywords().size() == 1) {
        // simple case, no need to process subqueries and do special escaping
        Keyword term = queryResults.getKeywords().iterator().next();
        highlightQuery.append(term.toString());
      } else {
        // find terms for this content hit
        List<String> hitTerms = new ArrayList<>();
        for (Keyword keyword : queryResults.getKeywords()) {
          for (KeywordHit hit : queryResults.getResults(keyword)) {
            if (hit.getContent().equals(content)) {
              hitTerms.add(keyword.toString());
              break; // go to next term
            }
          }
        }

        final int lastTerm = hitTerms.size() - 1;
        int curTerm = 0;
        for (String term : hitTerms) {
          // escape subqueries, they shouldn't be escaped again later
          final String termS = KeywordSearchUtil.escapeLuceneQuery(term);
          highlightQuery.append("\"");
          highlightQuery.append(termS);
          highlightQuery.append("\"");
          if (lastTerm != curTerm) {
            highlightQuery.append(" "); // acts as OR ||
            // force HIGHLIGHT_FIELD_REGEX index and stored content
            // in each term after first. First term taken care by HighlightedMatchesSource
            highlightQuery.append(LuceneQuery.HIGHLIGHT_FIELD_REGEX).append(":");
          }

          ++curTerm;
        }
      }
      // String highlightQueryEscaped =
      // KeywordSearchUtil.escapeLuceneQuery(highlightQuery.toString());
      highlightQueryEscaped = highlightQuery.toString();
    }

    return highlightQueryEscaped;
  }
    @Override
    protected Object doInBackground() throws Exception {
      logger.log(Level.INFO, "Pending start of new searcher");

      final String displayName = "Keyword Search" + (finalRun ? " - Finalizing" : "");
      progress =
          ProgressHandleFactory.createHandle(
              displayName + (" (Pending)"),
              new Cancellable() {

                @Override
                public boolean cancel() {
                  logger.log(Level.INFO, "Cancelling the searcher by user.");
                  if (progress != null) {
                    progress.setDisplayName(displayName + " (Cancelling...)");
                  }
                  return Searcher.this.cancel(true);
                }
              });

      progress.start();
      progress.switchToIndeterminate();

      // block to ensure previous searcher is completely done with doInBackground()
      // even after previous searcher cancellation, we need to check this
      searcherLock.lock();
      try {
        logger.log(Level.INFO, "Started a new searcher");
        progress.setDisplayName(displayName);
        // make sure other searchers are not spawned
        searcherDone = false;
        runSearcher = false;
        if (searchTimer.isRunning()) {
          searchTimer.stop();
        }

        int numSearched = 0;

        updateKeywords();
        progress.switchToDeterminate(keywords.size());

        for (Keyword keywordQuery : keywords) {
          if (this.isCancelled()) {
            logger.log(
                Level.INFO,
                "Cancel detected, bailing before new keyword processed: "
                    + keywordQuery.getQuery());
            return null;
          }
          final String queryStr = keywordQuery.getQuery();
          final KeywordSearchList list = keywordToList.get(queryStr);
          final String listName = list.getName();

          // DEBUG
          // logger.log(Level.INFO, "Searching: " + queryStr);

          progress.progress(queryStr, numSearched);

          KeywordSearchQuery del = null;

          boolean isRegex = !keywordQuery.isLiteral();
          if (!isRegex) {
            del = new LuceneQuery(keywordQuery);
            del.escape();
          } else {
            del = new TermComponentQuery(keywordQuery);
          }

          Map<String, List<ContentHit>> queryResult = null;

          try {
            queryResult = del.performQuery();
          } catch (NoOpenCoreException ex) {
            logger.log(Level.WARNING, "Error performing query: " + keywordQuery.getQuery(), ex);
            // no reason to continue with next query if recovery failed
            // or wait for recovery to kick in and run again later
            // likely case has closed and threads are being interrupted
            return null;
          } catch (CancellationException e) {
            logger.log(
                Level.INFO,
                "Cancel detected, bailing during keyword query: " + keywordQuery.getQuery());
            return null;
          } catch (Exception e) {
            logger.log(Level.WARNING, "Error performing query: " + keywordQuery.getQuery(), e);
            continue;
          }

          // calculate new results but substracting results already obtained in this run
          Map<Keyword, List<ContentHit>> newResults = new HashMap<Keyword, List<ContentHit>>();

          for (String termResult : queryResult.keySet()) {
            List<ContentHit> queryTermResults = queryResult.get(termResult);
            Keyword termResultK = new Keyword(termResult, !isRegex);
            List<ContentHit> curTermResults = currentResults.get(termResultK);
            if (curTermResults == null) {
              currentResults.put(termResultK, queryTermResults);
              newResults.put(termResultK, queryTermResults);
            } else {
              // some AbstractFile hits already exist for this keyword
              for (ContentHit res : queryTermResults) {
                if (!previouslyHit(curTermResults, res)) {
                  // add to new results
                  List<ContentHit> newResultsFs = newResults.get(termResultK);
                  if (newResultsFs == null) {
                    newResultsFs = new ArrayList<ContentHit>();
                    newResults.put(termResultK, newResultsFs);
                  }
                  newResultsFs.add(res);
                  curTermResults.add(res);
                }
              }
            }
          }

          if (!newResults.isEmpty()) {

            // write results to BB

            // new artifacts created, to report to listeners
            Collection<BlackboardArtifact> newArtifacts = new ArrayList<BlackboardArtifact>();

            for (final Keyword hitTerm : newResults.keySet()) {
              List<ContentHit> contentHitsAll = newResults.get(hitTerm);
              Map<AbstractFile, Integer> contentHitsFlattened =
                  ContentHit.flattenResults(contentHitsAll);
              for (final AbstractFile hitFile : contentHitsFlattened.keySet()) {
                String snippet = null;
                final String snippetQuery =
                    KeywordSearchUtil.escapeLuceneQuery(hitTerm.getQuery(), true, false);
                int chunkId = contentHitsFlattened.get(hitFile);
                try {
                  snippet =
                      LuceneQuery.querySnippet(
                          snippetQuery, hitFile.getId(), chunkId, isRegex, true);
                } catch (NoOpenCoreException e) {
                  logger.log(Level.WARNING, "Error querying snippet: " + snippetQuery, e);
                  // no reason to continue
                  return null;
                } catch (Exception e) {
                  logger.log(Level.WARNING, "Error querying snippet: " + snippetQuery, e);
                  continue;
                }

                KeywordWriteResult written =
                    del.writeToBlackBoard(hitTerm.getQuery(), hitFile, snippet, listName);

                if (written == null) {
                  logger.log(
                      Level.WARNING,
                      "BB artifact for keyword hit not written, file: "
                          + hitFile
                          + ", hit: "
                          + hitTerm.toString());
                  continue;
                }

                newArtifacts.add(written.getArtifact());

                // generate a data message for each artifact
                StringBuilder subjectSb = new StringBuilder();
                StringBuilder detailsSb = new StringBuilder();
                // final int hitFiles = newResults.size();

                if (!keywordQuery.isLiteral()) {
                  subjectSb.append("RegExp hit: ");
                } else {
                  subjectSb.append("Keyword hit: ");
                }
                // subjectSb.append("<");
                String uniqueKey = null;
                BlackboardAttribute attr =
                    written.getAttribute(
                        BlackboardAttribute.ATTRIBUTE_TYPE.TSK_KEYWORD.getTypeID());
                if (attr != null) {
                  final String keyword = attr.getValueString();
                  subjectSb.append(keyword);
                  uniqueKey = keyword.toLowerCase();
                }

                // subjectSb.append(">");
                // String uniqueKey = queryStr;

                // details
                detailsSb.append("<table border='0' cellpadding='4' width='280'>");
                // hit
                detailsSb.append("<tr>");
                detailsSb.append("<th>Keyword hit</th>");
                detailsSb
                    .append("<td>")
                    .append(StringEscapeUtils.escapeHtml(attr.getValueString()))
                    .append("</td>");
                detailsSb.append("</tr>");

                // preview
                attr =
                    written.getAttribute(
                        BlackboardAttribute.ATTRIBUTE_TYPE.TSK_KEYWORD_PREVIEW.getTypeID());
                if (attr != null) {
                  detailsSb.append("<tr>");
                  detailsSb.append("<th>Preview</th>");
                  detailsSb
                      .append("<td>")
                      .append(StringEscapeUtils.escapeHtml(attr.getValueString()))
                      .append("</td>");
                  detailsSb.append("</tr>");
                }

                // file
                detailsSb.append("<tr>");
                detailsSb.append("<th>File</th>");
                if (hitFile.getType().equals(TskData.TSK_DB_FILES_TYPE_ENUM.FS)) {
                  detailsSb
                      .append("<td>")
                      .append(((FsContent) hitFile).getParentPath())
                      .append(hitFile.getName())
                      .append("</td>");
                } else {
                  detailsSb.append("<td>").append(hitFile.getName()).append("</td>");
                }
                detailsSb.append("</tr>");

                // list
                attr =
                    written.getAttribute(
                        BlackboardAttribute.ATTRIBUTE_TYPE.TSK_SET_NAME.getTypeID());
                detailsSb.append("<tr>");
                detailsSb.append("<th>List</th>");
                detailsSb.append("<td>").append(attr.getValueString()).append("</td>");
                detailsSb.append("</tr>");

                // regex
                if (!keywordQuery.isLiteral()) {
                  attr =
                      written.getAttribute(
                          BlackboardAttribute.ATTRIBUTE_TYPE.TSK_KEYWORD_REGEXP.getTypeID());
                  if (attr != null) {
                    detailsSb.append("<tr>");
                    detailsSb.append("<th>RegEx</th>");
                    detailsSb.append("<td>").append(attr.getValueString()).append("</td>");
                    detailsSb.append("</tr>");
                  }
                }
                detailsSb.append("</table>");

                // check if should send messages on hits on this list
                if (list.getIngestMessages()) // post ingest inbox msg
                {
                  managerProxy.postMessage(
                      IngestMessage.createDataMessage(
                          ++messageID,
                          instance,
                          subjectSb.toString(),
                          detailsSb.toString(),
                          uniqueKey,
                          written.getArtifact()));
                }
              } // for each term hit
            } // for each file hit

            // update artifact browser
            if (!newArtifacts.isEmpty()) {
              IngestManager.fireServiceDataEvent(
                  new ServiceDataEvent(MODULE_NAME, ARTIFACT_TYPE.TSK_KEYWORD_HIT, newArtifacts));
            }
          }
          progress.progress(queryStr, ++numSearched);
        }

      } // end try block
      catch (Exception ex) {
        logger.log(Level.WARNING, "searcher exception occurred", ex);
      } finally {
        finalizeSearcher();
        searcherLock.unlock();
      }

      return null;
    }
  @Override
  public QueryResults performQuery() throws NoOpenCoreException {
    /*
     * Execute the regex query to get a list of terms that match the regex.
     * Note that the field that is being searched is tokenized based on
     * whitespace.
     */
    // create the query
    final SolrQuery q = new SolrQuery();
    q.setRequestHandler(TERMS_HANDLER);
    q.setTerms(true);
    q.setTermsRegexFlag(CASE_INSENSITIVE);
    q.setTermsRegex(escapedQuery);
    q.addTermsField(TERMS_SEARCH_FIELD);
    q.setTimeAllowed(TERMS_TIMEOUT);
    q.setShowDebugInfo(DEBUG);
    q.setTermsLimit(MAX_TERMS_RESULTS);
    LOGGER.log(Level.INFO, "Query: {0}", q.toString()); // NON-NLS

    // execute the query
    List<Term> terms = null;
    try {
      terms = KeywordSearch.getServer().queryTerms(q).getTerms(TERMS_SEARCH_FIELD);
    } catch (KeywordSearchModuleException ex) {
      LOGGER.log(
          Level.SEVERE,
          "Error executing the regex terms query: " + keyword.getQuery(),
          ex); // NON-NLS
      // TODO: this is almost certainly wrong and guaranteed to throw a NPE at some point!!!!
    }

    /*
     * For each term that matched the regex, query for full set of document
     * hits for that term.
     */
    QueryResults results = new QueryResults(this, keywordList);
    int resultSize = 0;

    for (Term term : terms) {
      final String termStr = KeywordSearchUtil.escapeLuceneQuery(term.getTerm());

      if (keyword.getType() == ATTRIBUTE_TYPE.TSK_CARD_NUMBER) {
        // If the keyword is a credit card number, pass it through luhn validator
        Matcher matcher = CCN_PATTERN.matcher(term.getTerm());
        matcher.find();
        final String ccn = CharMatcher.anyOf(" -").removeFrom(matcher.group("ccn"));
        if (false == LUHN_CHECK.isValid(ccn)) {
          continue; // if the hit does not pass the luhn check, skip it.
        }
      }

      /*
       * Note: we can't set filter query on terms query but setting filter
       * query on fileResults query will yield the same result
       */
      LuceneQuery filesQuery = new LuceneQuery(keywordList, new Keyword(termStr, true));
      filters.forEach(filesQuery::addFilter);

      try {
        QueryResults fileQueryResults = filesQuery.performQuery();
        Set<KeywordHit> filesResults = new HashSet<>();
        for (Keyword key : fileQueryResults.getKeywords()) { // flatten results into a single list
          List<KeywordHit> keyRes = fileQueryResults.getResults(key);
          resultSize += keyRes.size();
          filesResults.addAll(keyRes);
        }
        results.addResult(new Keyword(term.getTerm(), false), new ArrayList<>(filesResults));
      } catch (NoOpenCoreException | RuntimeException e) {
        LOGGER.log(Level.WARNING, "Error executing Solr query,", e); // NON-NLS
        throw e;
      }
    }

    // TODO limit how many results we store, not to hit memory limits
    LOGGER.log(Level.INFO, "Regex # results: {0}", resultSize); // NON-NLS

    return results;
  }