package us.codecraft.webmagic.selector;
   
   import org.w3c.dom.Node;
   import org.w3c.dom.NodeList;
   
   import javax.xml.transform.OutputKeys;
   import javax.xml.transform.Transformer;
   import javax.xml.transform.TransformerException;
   import javax.xml.transform.TransformerFactory;
  import javax.xml.transform.dom.DOMSource;
  import javax.xml.transform.stream.StreamResult;
  import java.io.StringWriter;
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.List;
  
  /**
   * @author hooy
   */
  public final class JaxpSelectorUtils {
  
      private JaxpSelectorUtils() {
          throw new RuntimeException("The util class cannot be instanced");
      }
  
      public static List<Node> NodeListToArrayList(NodeList nodes) {
          List<Node> list = new ArrayList<>(nodes.getLength());
          for (int i = 0; i < nodes.getLength(); i++) {
              list.add(nodes.item(i));
          }
          return list;
      }
  
      public static String nodeToString(Node node) throws TransformerException {
          List<Node> before = Collections.singletonList(node);
          List<String> after = nodesToStrings(before);
          if (after.size() > 0) {
              return after.get(0);
          } else {
              return null;
          }
      }
  
      public static List<String> nodesToStrings(List<Node> nodes) throws TransformerException {
          List<String> results = new ArrayList<>(nodes.size());
          Transformer transformer = TransformerFactory.newInstance().newTransformer();
          StreamResult xmlOutput = new StreamResult();
          transformer.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");
          for (Node node : nodes) {
              if (node.getNodeType() == Node.ATTRIBUTE_NODE || node.getNodeType() == Node.TEXT_NODE) {
                  results.add(node.getTextContent());
              } else {
                  xmlOutput.setWriter(new StringWriter());
                  transformer.transform(new DOMSource(node), xmlOutput);
                  results.add(xmlOutput.getWriter().toString());
              }
          }
          return results;
      }
  
  }