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);

            }

        }

    }

}