import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.SimpleTimeZone;

public class SatelliteDate {
        
    private GregorianCalendar calendar = new GregorianCalendar();
    
    public SatelliteDate()
    { 
        calendar.setTime(new Date());
        setTimes();     
    }
    
    public SatelliteDate(int month, int day, int year)
    { 
        calendar.set(Calendar.DAY_OF_MONTH, day);
        calendar.set(Calendar.YEAR, year);
        // month is 0..11
        calendar.set(Calendar.MONTH, month-1); 
        setTimes();
    }
        
    private void setTimes()
    {
        // eastern time is default from OS. nasa's images are UTC
        calendar.setTimeZone(new SimpleTimeZone(0, "UTC"));
        // subtract 24 hours so ending image is current time
        calendar.add(Calendar.HOUR_OF_DAY, -24);
    }

   
    public void addHours(int hourdelta)
    {
        calendar.add(Calendar.HOUR_OF_DAY, hourdelta);
    }
    
    public String toString()
    {
        int hour = calendar.get(Calendar.HOUR_OF_DAY);
        String hourString;
        if (hour < 10)
            hourString = "0" + hour;
        else
            hourString = "" + hour;
                
        String satDate = "" + calendar.get(Calendar.YEAR)
            + calendar.get(Calendar.DAY_OF_YEAR)
            + hourString;
        // get rid of first two digits of year
        satDate = satDate.substring(2);
        return satDate;
    }
}