module tools.TimeTools;

private
  import tango.time.chrono.Calendar, tango.text.locale.Core;

debug {
  import tango.io.Stdout;
}

alias Calendar.DayOfWeek DayOfWeek;

/***
 * Convert the DayOfWeek to his position in the week (0..6)
 * 
 * Params:
 *     dateTimeFormat = 
 *     dow = 
 * Returns:
 */
uint getPosDayOfWeek(DateTimeFormat dateTimeFormat, DayOfWeek dow) {

  uint firstDowNum = cast(uint) dateTimeFormat.firstDayOfWeek();

  uint dowInt = cast(uint) dow;

  if(firstDowNum < dowInt)
    return dowInt - firstDowNum;
  else
    return dowInt - firstDowNum + 7;

}

/***
 * Convert the position of a day in a week (0..6) to the DayOfWeek
 * 
 * Params:
 *     dateTimeFormat = 
 *     numDow = 
 * Returns:
 */
DayOfWeek convertPosDayOfWeek(DateTimeFormat dateTimeFormat, uint numDow)
in {
  assert(numDow < 8);
}
body {

  uint firstDowNum = cast(uint) dateTimeFormat.firstDayOfWeek();

  uint cvt = numDow + firstDowNum;

  if(cvt > 6)
    return cast(DayOfWeek) (cvt - 7);
  else
    return cast(DayOfWeek) cvt;
}