/**
  * Returns the HTTP encoded string required for web service authentication.
  *
  * <p>Order of authentication methods: token then username/password, if token not initialised or
  * null if both methods not initialised.
  *
  * @return String containing HTTP encoded string or null.
  * @throws UnsupportedEncodingException
  */
 public static String getAuth() throws UnsupportedEncodingException {
   StringBuilder data = new StringBuilder();
   if (MoodleCallRestWebService.getToken() != null) {
     data.append(URLEncoder.encode("wstoken", "UTF-8"))
         .append("=")
         .append(URLEncoder.encode(MoodleCallRestWebService.getToken(), "UTF-8"));
   } else {
     if (MoodleCallRestWebService.getUsername() != null
         && MoodleCallRestWebService.getPassword() != null) {
       data.append(URLEncoder.encode("wsusername", "UTF-8"))
           .append("=")
           .append(URLEncoder.encode(MoodleCallRestWebService.getUsername(), "UTF-8"));
       data.append("&"); // Fix by César Martínez
       data.append(URLEncoder.encode("wspassword", "UTF-8"))
           .append("=")
           .append(URLEncoder.encode(MoodleCallRestWebService.getPassword(), "UTF-8"));
     } else return null;
   }
   return data.toString();
 }
  @Override
  public HashSet<ScoredAnnotation> solveSa2W(String text) throws AnnotationException {
    HashSet<ScoredAnnotation> res;
    try {
      res = new HashSet<ScoredAnnotation>();
      lastTime = Calendar.getInstance().getTimeInMillis();

      URL wikiApi = new URL(url);
      String parameters =
          "references=true&repeatMode=all&minProbability=0.0&source="
              + URLEncoder.encode(text, "UTF-8");
      HttpURLConnection slConnection = (HttpURLConnection) wikiApi.openConnection();
      slConnection.setRequestProperty("accept", "text/xml");
      slConnection.setDoOutput(true);
      slConnection.setDoInput(true);
      slConnection.setRequestMethod("POST");
      slConnection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
      slConnection.setRequestProperty("charset", "utf-8");
      slConnection.setRequestProperty(
          "Content-Length", "" + Integer.toString(parameters.getBytes().length));
      slConnection.setUseCaches(false);

      DataOutputStream wr = new DataOutputStream(slConnection.getOutputStream());
      wr.writeBytes(parameters);
      wr.flush();
      wr.close();
      DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
      DocumentBuilder builder = factory.newDocumentBuilder();
      Document doc = builder.parse(slConnection.getInputStream());

      /*			URL wikiApi = new URL(url+"?references=true&repeatMode=all&minProbability=0.0&source="+URLEncoder.encode(text, "UTF-8"));
      			URLConnection wikiConnection = wikiApi.openConnection();
      			DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
      			DocumentBuilder builder = factory.newDocumentBuilder();
      			Document doc = builder.parse(wikiConnection.getInputStream());
      */

      lastTime = Calendar.getInstance().getTimeInMillis() - lastTime;

      XPathFactory xPathfactory = XPathFactory.newInstance();
      XPath xpath = xPathfactory.newXPath();
      XPathExpression idExpr = xpath.compile("//detectedTopic/@id");
      XPathExpression weightExpr = xpath.compile("//detectedTopic/@weight");
      XPathExpression referenceExpr = xpath.compile("//detectedTopic/references");

      NodeList ids = (NodeList) idExpr.evaluate(doc, XPathConstants.NODESET);
      NodeList weights = (NodeList) weightExpr.evaluate(doc, XPathConstants.NODESET);
      NodeList references = (NodeList) referenceExpr.evaluate(doc, XPathConstants.NODESET);

      for (int i = 0; i < weights.getLength(); i++) {
        if (weights.item(i).getNodeType() != Node.TEXT_NODE) {
          int id = Integer.parseInt(ids.item(i).getNodeValue());
          float weight = Float.parseFloat(weights.item(i).getNodeValue());
          //					System.out.println("ID="+ids.item(i).getNodeValue()+" weight="+weight);
          XPathExpression startExpr =
              xpath.compile("//detectedTopic[@id=" + id + "]/references/reference/@start");
          XPathExpression endExpr =
              xpath.compile("//detectedTopic[@id=" + id + "]/references/reference/@end");
          NodeList starts =
              (NodeList) startExpr.evaluate(references.item(i), XPathConstants.NODESET);
          NodeList ends = (NodeList) endExpr.evaluate(references.item(i), XPathConstants.NODESET);
          for (int j = 0; j < starts.getLength(); j++) {
            int start = Integer.parseInt(starts.item(j).getNodeValue());
            int end = Integer.parseInt(ends.item(j).getNodeValue());
            int len = end - start;
            res.add(new ScoredAnnotation(start, len, id, weight));
          }
        }
      }
    } catch (Exception e) {
      e.printStackTrace();
      throw new AnnotationException(
          "An error occurred while querying Wikipedia Miner API. Message: " + e.getMessage());
    }
    return res;
  }