package won.protocol.util;

import org.apache.jena.datatypes.xsd.XSDDatatype;
import org.apache.jena.datatypes.xsd.XSDDateTime;
import org.apache.jena.rdf.model.Literal;
import org.apache.jena.rdf.model.Model;
import org.apache.jena.rdf.model.RDFNode;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;

/**
 * User: atus
 * Date: 23.04.13
 */
public class DateTimeUtils
{
  private static final Logger logger = LoggerFactory.getLogger(DateTimeUtils.class);
  private static SimpleDateFormat sdf;
  private static final String DATE_FORMAT_XSD_DATE_TIME_STAMP = "yyyy-MM-DD'T'hh:mm:ss.sssZ";

  /**
   * Formats the date as xsd:dateTimeStamp (time stamp with timezone info).
   * @param date
   * @return
   */
  //TODO: here, we're using Calendar's default time zone!! Should be the timezone used by the creator of the Date object
  public static Literal toLiteral(Date date, Model model) {
    if (date == null) return null;
    Calendar cal = Calendar.getInstance();
    cal.setTime(date);
    XSDDateTime dateTime = new XSDDateTime(cal);
    return model.createTypedLiteral(dateTime, XSDDatatype.XSDdateTime);
  }

  /**
   * Returns the current date as xsd:dateTimeStamp (time stamp with timezone info).
   * @return
   */
  public  static Literal getCurrentDateTimeStamp(Model model) {
    return toLiteral(new Date(), model);
  }

  public static Date toDate(Literal literal, Model model){
    if (XSDDatatype.XSDdateTime.equals(literal.getDatatype())) {
      XSDDateTime dateTime = (XSDDateTime) XSDDatatype.XSDdateTime.parse(literal.getLexicalForm());
      return dateTime.asCalendar().getTime();
    } else if (literal.getDatatype() == null){
      //if the literal is not typed, try to interpret it as an xsd:dateTime
      Literal asXsdDateTime = model.createTypedLiteral(literal.getLexicalForm(), XSDDatatype.XSDdateTime);
      return toDate(asXsdDateTime, model);
    }
    return null;
  }

  /**
   * Parses the specified date, which is expected to be an xsd:dateTimeStamp (time stamp with timezone info).
   * @param date
   * @return the date or null if the format is not recognized
   */
  public static Date parse(String date, Model model) {
    return toDate(model.createTypedLiteral(date, XSDDatatype.XSDdateTime), model);
  }

  /**
   * Converts node to Date if it is a literal, returns null otherwise.
   * @param node
   * @param model
   * @return
   */
  public static Date toDate(RDFNode node, Model model){
    if (!node.isLiteral()) return null;
    Literal nodeAsLiteral = node.asLiteral();
    return toDate(nodeAsLiteral, model);
  }
}