//    datetime.h
//
//     date and time routines for GPS Processing
//     This is a modfied version of the original routines created by
//     Charles Schwarz and Gordon Adams.  The functions were modified to
//     use the Remondi Date/Time algorithms (see Hilla & Jackson (2000),
//     The GPS Toolbox: The Remondi Date/Time Algorithms, GPS Solutions,
//     3(4), 71-74 ).
//
//  DateTime provides the following formats for representing a GPS-time:
//         1. GPS time (GPS week and second of week)
//         2. Modified Julian Date (MJD and fraction-of-a-day)
//         3. Year, day-of-year, hour, minute, seconds
//         4. Year, Month, day, hour, minute, seconds
//
// An object of the class DateTime may be initialized (constructed) from
//   any of the representations and viewed in any other representation.
//

#if !defined( DATETIME_ )
#define  DATETIME_

#if !defined(IOSTREAM_)
#include <iostream>
#define IOSTREAM_
#endif

namespace NGSdatetime {

   using std::ostream;

   typedef struct{
      long        GPSWeek;
      double      secsOfWeek;
   }  GPSTime;

   typedef struct{
      long        mjd;
      double      fracOfDay;
   }  MJD;

   typedef struct{
      long         year;
      long         dayOfYear;
      long         hour;
      long         min;
      double       sec;
   }  YDOYHMS;

   typedef struct{
      long         year;
      long         month;
      long         day;
      long         hour;
      long         min;
      double       sec;
   }  YMDHMS;

   class DateTime
   {
      friend ostream &operator<<( ostream &output, DateTime &dt );

      public:
         // constructors
         DateTime();
         DateTime( GPSTime gpstime );
         DateTime( MJD  mjd );
         DateTime( YDOYHMS yearDoyHMS );
         DateTime( YMDHMS yearMonthDayHMS );
         DateTime( long year, long month, long day,
	           long hour, long min, double sec );

         // destructor
         ~DateTime();

         // initializers
         void  SetGPSTime( GPSTime gpstime );
         void  SetMJD( MJD  mjd );
         void  SetYDOYHMS( YDOYHMS yearDoyHMS );
         void  SetYMDHMS( YMDHMS yearMonthDayHMS );
         void  SetYMDHMS( long year, long month, long day,
	                  long hour, long min, double sec );

         // selectors
         GPSTime      GetGPSTime();
         MJD          GetMJD();
         YDOYHMS      GetYDOYHMS();
         YMDHMS       GetYMDHMS();

         // manipulators
         const DateTime &operator=(const DateTime &DT2);
	 DateTime* operator&(DateTime input);

         DateTime operator + ( const double days );
         double   operator - ( const DateTime &DT2 );

         bool    operator == ( const DateTime &DT2 );
         bool    operator != ( const DateTime &DT2 );
         bool    operator >  ( const DateTime &DT2 );
         bool    operator >= ( const DateTime &DT2 );
         bool    operator <  ( const DateTime &DT2 );
         bool    operator <= ( const DateTime &DT2 );

      private:
         long        mjd;
         double      fractionOfDay;
   };

} // namespace NGSdatetime

#endif