------------------------------------------------------------------
-- Tokeneer ID Station Core Software
--
-- Copyright (2003) United States Government, as represented
-- by the Director, National Security Agency. All rights reserved.
--
-- This material was originally developed by Praxis High Integrity
-- Systems Ltd. under contract to the National Security Agency.
------------------------------------------------------------------

------------------------------------------------------------------
-- Clock.Interface
--
-- Description:
--    Interface to the system clock.
--
-- Implementation Notes:
--     This packge body is not presented to the SPARK Examiner.
------------------------------------------------------------------
with Ada.Calendar;
use Ada.Calendar;

package body Clock.Interface
is

   ------------------------------------------------------------------
   -- Convert
   --
   -- Description:
   --    Converts Calendar.Time to Clock.TimeT
   --
   -- Implementation Notes:
   --    None.
   --
   ------------------------------------------------------------------
   function Convert (T : Ada.Calendar.Time) return Clock.TimeT
   is
      Year      : Ada.Calendar.Year_Number;
      Month     : Ada.Calendar.Month_Number;
      Day       : Ada.Calendar.Day_Number;
      Sec       : Duration;
   begin
      Ada.Calendar.Split
        (Date    => T,
         Year    => Year,
         Month   => Month,
         Day     => Day,
         Seconds => Sec);

      -- force truncating not rounding to ensure MilliSec doesn't overflow
      if Sec > 0.0005 then
         Sec := Sec - 0.0005;
      end if;

      return  Clock.TimeT'
        (Year      => Clock.YearsT(Year),
         Month     => Clock.MonthsT(Month),
         Day       => Clock.DaysT(Day),
         MilliSec  => Clock.MillisecsT( Sec * Clock.MilliSecsInSec )
         );
   end Convert;


   ------------------------------------------------------------------
   -- TheTime
   --
   -- Implementation Notes:
   --    None.
   --
   ------------------------------------------------------------------
   function TheTime return Clock.TimeT
   is
   begin
      return Convert(Ada.Calendar.Clock);
   end TheTime;

   ------------------------------------------------------------------
   -- AddDuration
   --
   -- Implementation Notes:
   --     If the time is not valid the duration is not added.
   --     If the addition causes an overflow then the duration is not added.
   --
   ------------------------------------------------------------------
   function AddDuration ( T : Clock.TimeT ; D : Clock.DurationT )
                         return Clock.TimeT
   is
      LocalTime : Ada.Calendar.Time;
   begin

      LocalTime := (Duration(D) / 10) +
        Ada.Calendar.Time_Of
        (Year    => Ada.Calendar.Year_Number(T.Year),
         Month   => Ada.Calendar.Month_Number(T.Month),
         Day     => Ada.Calendar.Day_Number(T.Day),
         Seconds => Ada.Calendar.Day_Duration
         ( Duration(T.MilliSec) / 1000));

      return Convert(LocalTime);

   exception when Ada.Calendar.Time_Error =>
      return T;
   end AddDuration;

   ------------------------------------------------------------------
   -- IsValidTime
   --
   -- Description:
   --    If the time can be converted to a system time then it is valid.
   --
   ------------------------------------------------------------------
   function IsValidTime ( T : Clock.TimeT ) return Boolean
   is
      LocalTime : Ada.Calendar.Time;
   begin
      LocalTime :=
        Ada.Calendar.Time_Of
        (Year    => Ada.Calendar.Year_Number(T.Year),
         Month   => Ada.Calendar.Month_Number(T.Month),
         Day     => Ada.Calendar.Day_Number(T.Day),
         Seconds => Ada.Calendar.Day_Duration( Duration(T.MilliSec) / 1000));

      return True;

   exception when Ada.Calendar.Time_Error =>
      return False;
   end IsValidTime;


end Clock.Interface;
