ERF_EpochTime.H

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#ifndef ERF_EPOCH_TIME_H_
#define ERF_EPOCH_TIME_H_
 
#include <string>
#include <sstream>
#include <iomanip>
#include <ctime>
 
#ifdef _WIN32
#define timegm _mkgmtime
#endif
 
AMREX_FORCE_INLINE
std::time_t getEpochTime(const std::string& dateTime, const std::string& dateTimeFormat) {
    std::tm tmTime{};
 
    (void)dateTimeFormat;
    // Manually parse the date string
    if (sscanf(dateTime.c_str(), "%d-%d-%d_%d:%d:%dUTC",
               &tmTime.tm_year, &tmTime.tm_mon, &tmTime.tm_mday,
               &tmTime.tm_hour, &tmTime.tm_min, &tmTime.tm_sec) != 6) {
        return -1; // Indicate failure if parsing fails
    }
 
    // Adjust year and month for tm structure
    tmTime.tm_year -= 1900; // tm_year is years since 1900
    tmTime.tm_mon -= 1;     // tm_mon is zero-based
 
    // Convert to epoch time (UTC)
    return timegm(&tmTime);
}
 
AMREX_FORCE_INLINE
std::string
getTimestamp (const amrex::Real epoch_real, const std::string& datetime_format)
{
    auto epoch_nearest_sec = static_cast<std::time_t>(epoch_real);
    std::tm *time_info = std::gmtime(&epoch_nearest_sec);
 
    char buffer[80];
    std::strftime(buffer, sizeof(buffer), datetime_format.c_str(), time_info);
    std::string str_nearest_sec(buffer);
 
    double frac_sec = epoch_real - epoch_nearest_sec;
    snprintf(buffer, 80, "%.6f", frac_sec);
    AMREX_ASSERT(buffer[0] == '0');
    std::string str_frac_sec(buffer);
 
    return str_nearest_sec + str_frac_sec.substr(1);
}
 
 
#endif