package org.madore.damlengine;

import java.util.regex.Pattern;
import java.io.InputStream;
import java.security.MessageDigest;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.xpath.*;
import org.w3c.dom.*;
import org.w3c.dom.ls.DOMImplementationLS;
import org.w3c.dom.ls.LSSerializer;
// import org.xml.sax.EntityResolver;

public final class WeblogPopulate {

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

    public static final String toHex(byte[] digest) {
	StringBuilder sb = new StringBuilder();
	for ( byte b : digest )
	    sb.append(String.format("%02x", b));
	return sb.toString();
    }

    public static void populate(InputStream in)
	throws Exception {

	final DocumentBuilder db = DamlEngine.GetDocumentBuilder.db;

	final DOMImplementationLS domi
	    = (DOMImplementationLS)(db.getDOMImplementation());
	LSSerializer ser = domi.createLSSerializer();
	ser.getDomConfig().setParameter("xml-declaration", false);

	MessageDigest sha1 = MessageDigest.getInstance("SHA-1");

	final Connection conn = WeblogDatabaseConnection.getConnection();

	final PreparedStatement checkSt
	    = conn.prepareStatement("SELECT sha1 FROM entries WHERE id=?");
	final PreparedStatement insertNSt
	    = conn.prepareStatement("INSERT INTO entries(id,edate,lang,title,title_xml,content,sha1) VALUES (?,?,?,?,?::xml,?::xml,?)");
	final PreparedStatement insertCSt
	    = conn.prepareStatement("INSERT INTO entries(id,edate,lang,title,title_xml,content,sha1,cdate) VALUES (?,?,?,?,?::xml,?::xml,?,?::timestamptz)");
	final PreparedStatement updateSt
	    = conn.prepareStatement("UPDATE entries SET (edate,mdate,lang,title,title_xml,content,sha1)=(?,DEFAULT,?,?,?::xml,?::xml,?) WHERE id=?");
	final PreparedStatement clearCatSt
	    = conn.prepareStatement("DELETE FROM incat WHERE id=?");
	final PreparedStatement setCatSt
	    = conn.prepareStatement("INSERT INTO incat(id,code) VALUES (?,?)");

	Document doc = db.parse(in);
	XPathFactory xpf = XPathFactory.newInstance();
	XPath xp = xpf.newXPath();
	xp.setNamespaceContext(new DamlEngine.DamlNSMapping());
	XPathExpression expr = xp.compile("//d:weblog/d:entry");
	XPathExpression texpr = xp.compile("d:title");
	NodeList entries = (NodeList)(expr.evaluate(doc, XPathConstants.NODESET));
	for ( int i=0 ; i<entries.getLength() ; i++ ) {
	    Element ent = (Element)(entries.item(i));
	    String idStr = ent.getAttributeNS(null, "number");
	    if ( ! Pattern.matches("^\\d{4}$", idStr) )
		throw new IllegalArgumentException("entry number attribute must be of the form NNNN");
	    int id = Integer.parseInt(idStr);
	    String date = ent.getAttributeNS(null, "date");
	    if ( ! Pattern.matches("^\\d{4}-\\d{2}-\\d{2}$", date) )
		throw new IllegalArgumentException("entry date attribute must be of the form YYYY-MM-DD");
	    String cdate;
	    if ( ent.hasAttributeNS(null, "cdate") )
		cdate = ent.getAttributeNS(null, "cdate");
	    else
		cdate = null;
	    String catStr = ent.getAttributeNS(null, "cat");
	    String[] catList = catStr.split("\\s+");
	    String lang = LangHelper.getLangRec(ent);
	    String content = ser.writeToString(ent);
	    sha1.reset();
	    String digest = toHex(sha1.digest(content.getBytes("UTF-8")));

	    checkSt.setInt(1, id);
	    ResultSet checkRes = checkSt.executeQuery();
	    boolean exists = checkRes.next();
	    if ( exists && checkRes.getString(1).equals(digest) )
		continue;
	    Node titleNode = (Node)(texpr.evaluate(ent, XPathConstants.NODE));
	    String titleTxt = (titleNode != null) ? titleNode.getTextContent() : null;
	    String titleXml = (titleNode != null) ? ser.writeToString(titleNode) : null;
	    conn.setAutoCommit(false);
	    if ( exists ) {
		System.err.println("Updating entry "+id);
		updateSt.setString(1, date);
		updateSt.setString(2, lang);
		updateSt.setString(3, titleTxt);
		updateSt.setString(4, titleXml);
		updateSt.setString(5, content);
		updateSt.setString(6, digest);
		updateSt.setInt(7, id);
		updateSt.executeUpdate();
	    } else {
		System.err.println("Registering entry "+id);
		PreparedStatement insertSt;
		if ( cdate == null )
		    insertSt = insertNSt;
		else
		    insertSt = insertCSt;
		insertSt.setInt(1, id);
		insertSt.setString(2, date);
		insertSt.setString(3, lang);
		insertSt.setString(4, titleTxt);
		insertSt.setString(5, titleXml);
		insertSt.setString(6, content);
		insertSt.setString(7, digest);
		if ( cdate != null )
		    insertSt.setString(8, cdate);
		insertSt.executeUpdate();
	    }
	    clearCatSt.setInt(1, id);
	    clearCatSt.executeUpdate();
	    for ( String cat : catList ) {
		if ( ! cat.equals("") ) {
		    setCatSt.setInt(1, id);
		    setCatSt.setString(2, cat);
		    setCatSt.executeUpdate();
		}
	    }
	    conn.commit();
	}

	checkSt.close();
	insertNSt.close();
	insertCSt.close();
	updateSt.close();
	clearCatSt.close();
	setCatSt.close();

    }

}