package page.tools.xml;

import java.io.IOException;
import java.io.StringWriter;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.Result;
import javax.xml.transform.Source;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.wikiwebserver.handler.http.HTTPException;
import org.wikiwebserver.handler.http.HTTPHandler;
import org.wikiwebserver.handler.http.interfaces.HTTPResponder;

public class RSSResponder implements HTTPResponder {
    
    private RSSChannel channel;
    
    public RSSResponder(RSSChannel channel) {
        this.channel = channel;
    }    
    

    public Object respond(HTTPHandler conn) throws IOException {
        
        conn.getResponse().getHeaders().set("Content-Type", "text/xml");
        conn.getResponse().getHeaders().set("Content-disposition", "inline; " +
        		"filename=" + channel.getName() + ".rss.xml");
        
        return getRSS();
    } 
    
    public String getRSS() throws HTTPException {
        
        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
        try {
            DocumentBuilder db  = dbf.newDocumentBuilder();
            Document doc = db.newDocument();
            
            Element rss = doc.createElement("rss");
            rss.setAttribute("version", "2.0");
            
            rss.appendChild(channel.getNode(doc));
            
            doc.appendChild(rss);

            StringWriter writer = new StringWriter();
            
            // Prepare the DOM document for writing
            Source source = new DOMSource(doc);
            Result result = new StreamResult(writer);

            // Write the DOM document to the file
            Transformer xformer = TransformerFactory.newInstance().newTransformer();
            //xformer.setOutputProperty(OutputKeys.ENCODING, "ISO-8859-1");

            xformer.transform(source, result);
            
            writer.close();
            
            return writer.toString();
            
        } catch (Exception e) {
            throw new HTTPException(500, "Failed to generate RSS", e);
        }
    }
}