/*

 * caltontp - convert a date to an NTP time

 */

#include <config.h>

#include <sys/types.h>

#include "ntp_types.h"

#include "ntp_calendar.h"

#include "ntp_stdlib.h"

#include "ntp_assert.h"

#include "ntp_unixtime.h"

/*

 * Juergen Perlinger, 2008-11-12

 * Add support for full calendar calculatios. If the day-of-year is provided

 * (that is, not zero) it will be used instead of month and day-of-month;

 * otherwise a full turn through the calendar calculations will be taken.

 *

 * I know that Harlan Stenn likes to see assertions in production code, and I

 * agree there, but it would be a tricky thing here. The algorithm is quite

 * capable of producing sensible answers even to seemingly weird inputs: the

 * date <any year here>-03-00, the 0.th March of the year, will be automtically

 * treated as the last day of February, no matter whether the year is a leap

 * year or not. So adding constraints is merely for the benefit of the callers,

 * because the only thing we can check for consistency is our input, produced

 * by somebody else.

 *

 * BTW: A total roundtrip using 'caljulian' would be a quite shaky thing:

 * Because of the truncation of the NTP time stamp to 32 bits and the epoch

 * unfolding around the current time done by 'caljulian' the roundtrip does

 * *not* necessarily reproduce the input, especially if the time spec is more

 * than 68 years off from the current time...

 */

uint32_t

caltontp(

  const struct calendar *jt

  )

{

  int32_t eraday; /* CE Rata Die number */

  vint64  ntptime;/* resulting NTP time */

  REQUIRE(jt != NULL);

  REQUIRE(jt->month <= 13);  /* permit month 0..13! */

  REQUIRE(jt->monthday <= 32);

  REQUIRE(jt->yearday <= 366);

  REQUIRE(jt->hour <= 24);

  REQUIRE(jt->minute <= MINSPERHR);

  REQUIRE(jt->second <= SECSPERMIN);

  /*

   * First convert the date to he corresponding RataDie

   * number. If yearday is not zero, assume that it contains a

   * useable value and avoid all calculations involving month

   * and day-of-month. Do a full evaluation otherwise.

   */

  if (jt->yearday)

    eraday = ntpcal_year_to_ystart(jt->year)

           + jt->yearday - 1;

  else

    eraday = ntpcal_date_to_rd(jt);

  ntptime = ntpcal_dayjoin(eraday - DAY_NTP_STARTS,

         ntpcal_etime_to_seconds(jt->hour, jt->minute,

               jt->second));

  return ntptime.d_s.lo;

}