#include <iostream>
#include <sstream>
#include <chrono>
#include <ctime>

#include "TString.h"
#include "TError.h"

TString fTimeFormat="%d/%m/%y%F2023-08-16 12:02:57s0";

long long GetGMTimeOffset() {

  Int_t idF = fTimeFormat.Index("%F")+2;
  if (idF<2) {
    Warning("GetGMTimeOffset","Time format is not set!");
    return 0;
  }
  TString stime=fTimeFormat(idF,19);
  if (stime.Length() != 19)
    Warning("GetGMTimeOffset","Bad time format!");
  
  //  Info("GetGMTimeOffset","String format='%s', index=%d, data='%s'",fTimeFormat.Data(),idF,stime.Data());
  //  return 0;
       
  std::tm tm = {};

  std::stringstream ss(stime.Data());

  // this works in script mode, but not in ACLiC, which is blind to get_time function:
  //  error: no member named 'get_time' in namespace 'std'
  // ss >> std::get_time(&tm, "%Y-%m-%d %H:%M:%S");

  if(!strptime(stime.Data(), "%Y-%m-%d %H:%M:%S", &tm)) { // not working at some systems
    Error("GetGMTimeOffset","failed to parse time!");
    return 0;
  }
  
  std::time_t time = std::mktime(&tm)   // Convert to time_t local time, unixtime
    ,localOffset = time - std::mktime(std::gmtime(&time)) // local offset, sec
    ,gmt_time = time - localOffset;     // GMT (UTC) unixtim
  
  //  Info("GetGMTimeOffset","Unix local time=%ld, time zone offset=%ld, unix GMT time=%ld",time,localOffset,gmt_time);
  
  return static_cast<long long>(gmt_time);
} //GetGMTimeOffset

int TAxis_GetGMTimeOffset() {
  long long unix_time = GetGMTimeOffset();
  Info("TAxis_GetGMTimeOffset","String format='%s', Unix time (GMT): %lld",fTimeFormat.Data(),unix_time);
  return 0;

}