//    datetime.h
//
//     gps day, time, and date routines
//
//
//  DateTime is an abstraction of the following ways of representing time:
//         1. GPS time (GPS week and second of week)
//         2. Modified Julian Date (MJD)
//         3. Year, day, hour, minute sec.
//         4. Year, Month, day, hour, minute, second
//
// An object of the class DateTime may be initialized (constructed) from
//   any of the representations and viewed in any other representation.
//

// Modification History.

// 27-Jul-00 -- Gordon Adams
//    Removed the DateTime:: from the operator + declaration.  This was
//    causing a complier error on HP which said that you cannot use the
//    "::" operator on an incompletely defined class.
//    Changed the "long double" declarations to "double".  long doulbe 
//    is over kill and adds nothing to the precision of the computations.


#if !defined( __DateTime__ )
   #define  __DateTime__

//
//  DateTime class is an abstraction of the following ways of representing
//  time:
//         1. GPS time (GPS week and second of week)
//         2. Modified Julian Date (MJD)
//         3. Year, day, hour, minute sec.
//         4. Year, Month, day, hour, minute, second
//
//  An object of the class DateTime may be initialized (constructed) from
//  any of the representations and viewed in any other representation.
//

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

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

   typedef struct{
      long     year;
      long     yday;
      long     hour;
      long     min;
      double   sec;
   }  YearDay;

   typedef struct{
      long     year;
      long     month;
      long     monthday;
      long     hour;
      long     min;
      double   sec;
   }  YearMonthDay;

   class DateTime
   {
      public:
// constructors

         DateTime();
         DateTime( GPSTime & gpstime );
         DateTime( MJD & mjd );
         DateTime( YearDay & yearday );
         DateTime( const YearMonthDay & yearmonthday );
         DateTime( unsigned long year, unsigned long month,
                   unsigned long monthday, unsigned long hour,
                   unsigned long min, double sec );

// initializers

         void  SetGPSTime( GPSTime & gpstime );
         void  SetMJD( MJD & mjd );
         void  SetYearDay( YearDay & yearday );
         void  SetYearMonthDay( const YearMonthDay & yearmonthday );
         void  SetYMDHMS( unsigned long year, unsigned long month,
                          unsigned long monthday, unsigned long hour,
                          unsigned long min, double sec );

// selectors

         double         GetGPSSeconds();
         GPSTime        GetGPSTime();
         MJD            GetMJD();
         YearDay        GetYearDay();
         YearMonthDay   GetYearMonthDay();

// manipulators

         DateTime operator + ( const double secs );
         double   operator - ( const DateTime &DT2 );
         int      operator == ( const DateTime &DT2 );
         int      operator != ( const DateTime &DT2 );
         int      operator >= ( const DateTime &DT2 );
         int      operator <  ( const DateTime &DT2 );

      private:
         long     GPSWeek;
         double   secsOfWeek;
   };

#endif