How to find the start day of thithi? about astrosoft HOT 4 CLOSED

    /*
    * calculate thithi starting date
    * */
    GregorianCalendar calStepperForDayBefore = (GregorianCalendar) currentDate.clone();
    while(panchangAtSunrise.getThithi().getStarting() == 0d){

        calStepperForDayBefore.add(Calendar.DAY_OF_MONTH,-1);
        calStepperForDayBefore = AstroUtil.atHourMinuteSecond(
                calStepperForDayBefore,
                AstroUtil.getSunRise(calStepperForDayBefore,place),
                false);

        Panchang panAtDayBefore = new Panchang(calStepperForDayBefore,person);

        if( panchangAtSunrise.getThithi().getThithi().getPreviousThithi() == panAtDayBefore.getThithi().getThithi() ){
            panchangAtSunrise.getThithi().setStarting(panAtDayBefore.getThithi().getEnding());
            panchangAtSunrise.getThithi().setStartingDate(panAtDayBefore.getThithi().getEndingDate());
        }
        else if(panchangAtSunrise.getThithi().getThithi().getPreviousThithi().getPreviousThithi() == panAtDayBefore.getThithi().getThithi()){
            // on DayBefore, there was two thithi
            // find panchang at end of that thithi
            double atDayBeforeAtThithiEnd = panAtDayBefore.getThithi().getEnding();
            GregorianCalendar atDayBeforeAtThithiEndCal = AstroUtil.atHourMinuteSecond(calStepperForDayBefore, atDayBeforeAtThithiEnd,true);
            Panchang panAtDayBeforeAtThithiEnd = new Panchang(
                    atDayBeforeAtThithiEndCal,
                    person);
            if(panAtDayBeforeAtThithiEnd.getThithi().getThithi() ==
                    panchangAtSunrise.getThithi().getThithi().getPreviousThithi()){
                panchangAtSunrise.getThithi().setStarting(panAtDayBeforeAtThithiEnd.getThithi().getEnding());
                panchangAtSunrise.getThithi().setStartingDate(panAtDayBeforeAtThithiEnd.getThithi().getEndingDate());
            }
            else{
                System.out.println("Should never happen");
            }
        }
    }