package org.madore.damlengine;

import java.util.regex.Pattern;
import java.util.regex.Matcher;
import java.io.OutputStream;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import org.w3c.dom.*;
import org.w3c.dom.ls.DOMImplementationLS;
import org.w3c.dom.ls.LSParser;
import org.w3c.dom.ls.LSSerializer;
import org.w3c.dom.ls.LSInput;
import org.w3c.dom.ls.LSOutput;

public final class WeblogRSS {

    private WeblogRSS() { // Forbid instantiation
	throw new AssertionError("WeblogRSS cannot be instantiated");
    }

    public static void fullProcess(OutputStream out)
	throws Exception {

	final String weblogBaseURI = "http://www.madore.org/~david/weblog/";

	final Connection conn = WeblogDatabaseConnection.getConnection();

	final PreparedStatement selSt
	    = conn.prepareStatement("SELECT id , edate , to_char(cdate,'YYYY-MM-DD\"T\"HH24:MI:SS\"Z\"') , lang , title , content FROM entries ORDER BY id DESC LIMIT 25");

	final ResultSet selRes = selSt.executeQuery();

	final DOMImplementation domi
	    = (DamlEngine.IncantDOM.getDOMI());
	final DOMImplementationLS domils = (DOMImplementationLS)(domi);
	LSSerializer ser = domils.createLSSerializer();
	ser.getDomConfig().setParameter("xml-declaration", true);
	LSParser par = domils.createLSParser(DOMImplementationLS.MODE_SYNCHRONOUS, null);

	final LSOutput lsout = domils.createLSOutput();
	lsout.setByteStream(out);
	lsout.setEncoding("UTF-8");

	Document rssDoc = domi.createDocument(DamlEngine.RDF_NS, "rdf:RDF", null);
	Element rssRoot = rssDoc.getDocumentElement();
	// rssDoc.appendChild(rssDoc.createTextNode("\n"));

	rssRoot.setAttributeNS(DamlEngine.XMLNS_NS, "xmlns:rdf", DamlEngine.RDF_NS);
	rssRoot.setAttributeNS(DamlEngine.XMLNS_NS, "xmlns", DamlEngine.RSS10_NS);
	rssRoot.setAttributeNS(DamlEngine.XMLNS_NS, "xmlns:dc", DamlEngine.DUBLINCORE_NS);
	rssRoot.setAttributeNS(DamlEngine.XMLNS_NS, "xmlns:sy", DamlEngine.SYNDICATION_NS);
	rssRoot.setAttributeNS(DamlEngine.XML_NS, "xml:lang", "en");
	rssRoot.appendChild(rssDoc.createTextNode("\n"));

	Element channel = rssDoc.createElementNS(DamlEngine.RSS10_NS, "channel");
	rssRoot.appendChild(channel);
	rssRoot.appendChild(rssDoc.createTextNode("\n"));
	channel.setAttributeNS(DamlEngine.RDF_NS, "rdf:about", weblogBaseURI);
	channel.appendChild(rssDoc.createTextNode("\n"));

	Element chanTitle = rssDoc.createElementNS(DamlEngine.RSS10_NS, "title");
	channel.appendChild(chanTitle);
	channel.appendChild(rssDoc.createTextNode("\n"));
	chanTitle.appendChild(rssDoc.createTextNode("David Madore's WebLog"));
	Element chanLink = rssDoc.createElementNS(DamlEngine.RSS10_NS, "link");
	channel.appendChild(chanLink);
	channel.appendChild(rssDoc.createTextNode("\n"));
	chanLink.appendChild(rssDoc.createTextNode(weblogBaseURI));
	Element chanDescription = rssDoc.createElementNS(DamlEngine.RSS10_NS, "description");
	channel.appendChild(chanDescription);
	channel.appendChild(rssDoc.createTextNode("\n"));
	chanDescription.appendChild(rssDoc.createTextNode("David Madore's WebLog"));
	Element syUpdatePeriod = rssDoc.createElementNS(DamlEngine.SYNDICATION_NS, "sy:updatePeriod");
	channel.appendChild(syUpdatePeriod);
	channel.appendChild(rssDoc.createTextNode("\n"));
	syUpdatePeriod.appendChild(rssDoc.createTextNode("hourly"));
	Element syUpdateFrequency = rssDoc.createElementNS(DamlEngine.SYNDICATION_NS, "sy:updateFrequency");
	channel.appendChild(syUpdateFrequency);
	channel.appendChild(rssDoc.createTextNode("\n"));
	syUpdateFrequency.appendChild(rssDoc.createTextNode("3"));
	Element syUpdateBase = rssDoc.createElementNS(DamlEngine.SYNDICATION_NS, "sy:updateBase");
	channel.appendChild(syUpdateBase);
	channel.appendChild(rssDoc.createTextNode("\n"));
	syUpdateBase.appendChild(rssDoc.createTextNode("2003-05-01T10:00:00Z"));
	Element chanItems = rssDoc.createElementNS(DamlEngine.RSS10_NS, "items");
	channel.appendChild(chanItems);
	channel.appendChild(rssDoc.createTextNode("\n"));
	chanItems.appendChild(rssDoc.createTextNode("\n"));
	Element itemsSeq = rssDoc.createElementNS(DamlEngine.RDF_NS, "rdf:Seq");
	chanItems.appendChild(itemsSeq);
	chanItems.appendChild(rssDoc.createTextNode("\n"));
	itemsSeq.appendChild(rssDoc.createTextNode("\n"));

	while ( selRes.next() ) {
	    int id = selRes.getInt(1);
	    String date = selRes.getString(2);
	    String cdate = selRes.getString(3);
	    String lang = selRes.getString(4);
	    String title = selRes.getString(5);
	    String contentXml = selRes.getString(6);
	    Matcher matcher = Pattern.compile("^(\\d{4})-(\\d{2})-(\\d{2})$").matcher(date);
	    if ( ! matcher.matches() )
		throw new IllegalArgumentException("entry "+id+" has badly formed date");
	    String yearStr = matcher.group(1);
	    String monthStr = matcher.group(2);
	    // String dayStr = matcher.group(3);
	    String numberStr = String.format("%04d",id);
	    String aboutUri = weblogBaseURI
		+ "#d." + date + "." + numberStr;
	    String linkUri = weblogBaseURI
		+ yearStr + "-" + monthStr + ".html"
		+ "#d." + date + "." + numberStr;
	    Element li = rssDoc.createElementNS(DamlEngine.RDF_NS, "rdf:li");
	    itemsSeq.appendChild(li);
	    itemsSeq.appendChild(rssDoc.createTextNode("\n"));
	    li.setAttributeNS(DamlEngine.RDF_NS, "rdf:resource",
			      aboutUri);
	    Element item = rssDoc.createElementNS(DamlEngine.RSS10_NS, "item");
	    rssRoot.appendChild(item);
	    rssRoot.appendChild(rssDoc.createTextNode("\n"));
	    item.setAttributeNS(DamlEngine.RDF_NS, "rdf:about",
				aboutUri);
	    item.setAttributeNS(DamlEngine.XML_NS, "xml:lang", lang);
	    item.appendChild(rssDoc.createTextNode("\n"));
	    Element itemTitle = rssDoc.createElementNS(DamlEngine.RSS10_NS, "title");
	    item.appendChild(itemTitle);
	    item.appendChild(rssDoc.createTextNode("\n"));
	    itemTitle.appendChild(rssDoc.createTextNode(title));
	    Element itemLink = rssDoc.createElementNS(DamlEngine.RSS10_NS, "link");
	    item.appendChild(itemLink);
	    item.appendChild(rssDoc.createTextNode("\n"));
	    itemLink.appendChild(rssDoc.createTextNode(linkUri));
	    Element itemDate = rssDoc.createElementNS(DamlEngine.DUBLINCORE_NS, "dc:date");
	    item.appendChild(itemDate);
	    item.appendChild(rssDoc.createTextNode("\n"));
	    itemDate.appendChild(rssDoc.createTextNode(cdate));
	    LSInput input = domils.createLSInput();
	    input.setStringData(contentXml);
	    Document temp = par.parse(input);
	    String contentStr = temp.getDocumentElement().getTextContent();
	    int bound;
	    try {
		bound = Character.offsetByCodePoints(contentStr, 0, 500);
	    } catch (IndexOutOfBoundsException e) {
		bound = contentStr.length();
	    }
	    String descrStr = contentStr.substring(0, bound).replace("\n"," ");
	    Element itemDescr = rssDoc.createElementNS(DamlEngine.RSS10_NS, "description");
	    item.appendChild(itemDescr);
	    item.appendChild(rssDoc.createTextNode("\n"));
	    itemDescr.appendChild(rssDoc.createTextNode(descrStr));
	}

	ser.write(rssDoc, lsout);
	out.write("\n".getBytes("UTF-8"));

    }

}