supercell-wx/wxdata/source/scwx/util/time.cpp

// Enable chrono formatters
#ifndef __cpp_lib_format
#   define __cpp_lib_format 202110L
#endif

#include <scwx/util/time.hpp>

namespace scwx
{
namespace util
{

std::chrono::system_clock::time_point TimePoint(uint32_t modifiedJulianDate,
                                                uint32_t milliseconds)
{
   using namespace std::chrono;
   using sys_days       = time_point<system_clock, days>;
   constexpr auto epoch = sys_days {1969y / December / 31d};

   return epoch + (modifiedJulianDate * 24h) +
          std::chrono::milliseconds {milliseconds};
}

std::string TimeString(std::chrono::system_clock::time_point time,
                       const std::chrono::time_zone*         timeZone,
                       bool                                  epochValid)
{
   using namespace std::chrono;
   auto               timeInSeconds = time_point_cast<seconds>(time);
   std::ostringstream os;

   if (epochValid || time.time_since_epoch().count() != 0)
   {
      if (timeZone != nullptr)
      {
         zoned_time zt = {current_zone(), timeInSeconds};
         os << zt;
      }
      else
      {
         os << timeInSeconds;
      }
   }

   return os.str();
}

} // namespace util
} // namespace scwx