package org.apidesign.bck2brwsr.htmlpage;

 import java.io.IOException;

 import java.io.InputStream;

 import java.util.Collections;

 import java.util.Map;

 import java.util.Set;

 import java.util.TreeMap;

 import javax.xml.parsers.DocumentBuilder;

 import javax.xml.parsers.DocumentBuilderFactory;

 import org.w3c.dom.Document;

 import org.w3c.dom.Element;

 import org.w3c.dom.Node;

 import org.w3c.dom.NodeList;

 class ProcessPage {

     private final Map<String,String> ids2Elems = new TreeMap<String, String>();

     public Set<String> ids() {

         return Collections.unmodifiableSet(ids2Elems.keySet());

     }

     public String tagNameForId(String id) {

         return ids2Elems.get(id);

     }

     public static ProcessPage readPage(InputStream is) throws IOException {

         DocumentBuilderFactory f = DocumentBuilderFactory.newInstance();

         f.setValidating(false);

         f.setIgnoringComments(true);

         Document doc = null;

         try {

             DocumentBuilder b = f.newDocumentBuilder();

             doc = b.parse(is);

         } catch (IOException ex) {

             throw ex;

         } catch (Exception e) {

             throw new IOException(e);

         }

         Element root = doc.getDocumentElement();

         ProcessPage pp = new ProcessPage();

         pp.seekForIds(root);

         return pp;

     }

     private void seekForIds(Element e) {

         String val = e.getAttribute("id");

         if (val != null && !val.isEmpty()) {

             String prev = ids2Elems.put(val, e.getTagName());

         }

         NodeList arr = e.getChildNodes();

         for (int i = 0; i < arr.getLength(); i++) {

             final Node n = arr.item(i);

             if (n instanceof Element) {

                 seekForIds((Element)n);

             }

         }

     }

 }