text: //
  // Copyright(c) 2015 Gabi Melman.
  // Distributed under the MIT License (http://opensource.org/licenses/MIT)
  //
  #pragma once
  
  #include <spdlog/common.h>
  
  #include <cstdio>
  #include <ctime>
  #include <functional>
  #include <string>
  #include <chrono>
  #include <stdio.h>
  #include <string.h>
  #include <sys/stat.h>
  
  
  #ifdef _WIN32
  
  #ifndef NOMINMAX
  #define NOMINMAX //prevent windows redefining min/max
  #endif
  
  #ifndef WIN32_LEAN_AND_MEAN
  #define WIN32_LEAN_AND_MEAN
  #endif
  #include <windows.h>
  #include <process.h>
  
  #ifdef __MINGW32__
  #include <share.h>
  #endif
  
  #include <sys/types.h>
  #include <io.h>
  
  #elif __linux__
  
  #include <sys/syscall.h> //Use gettid() syscall under linux to get thread id
  #include <unistd.h>
  
  #elif __FreeBSD__
  #include <sys/thr.h> //Use thr_self() syscall under FreeBSD to get thread id
  #include <unistd.h>
  
  #else
  #include <unistd.h> 
  #include <thread>
  
  #endif
  
  namespace spdlog
  {
  namespace details
  {
  namespace os
  {
  
  inline spdlog::log_clock::time_point now()
  {
  
  #if defined __linux__ && defined SPDLOG_CLOCK_COARSE
      timespec ts;
      ::clock_gettime(CLOCK_REALTIME_COARSE, &ts);
      return std::chrono::time_point<log_clock, typename log_clock::duration>(
                 std::chrono::duration_cast<typename log_clock::duration>(
                     std::chrono::seconds(ts.tv_sec) + std::chrono::nanoseconds(ts.tv_nsec)));
  
  
  #else
      return log_clock::now();
  #endif
  
  }
  inline std::tm localtime(const std::time_t &time_tt)
  {
  
  #ifdef _WIN32
      std::tm tm;
      localtime_s(&tm, &time_tt);
  #else
      std::tm tm;
      localtime_r(&time_tt, &tm);
  #endif
      return tm;
  }
  
  inline std::tm localtime()
  {
      std::time_t now_t = time(nullptr);
      return localtime(now_t);
  }
  
  
  inline std::tm gmtime(const std::time_t &time_tt)
  {
  
  #ifdef _WIN32
      std::tm tm;
      gmtime_s(&tm, &time_tt);
  #else
      std::tm tm;
      gmtime_r(&time_tt, &tm);
  #endif
      return tm;
  }
  
  inline std::tm gmtime()
  {
      std::time_t now_t = time(nullptr);
      return gmtime(now_t);
  }
  inline bool operator==(const std::tm& tm1, const std::tm& tm2)
  {
      return (tm1.tm_sec == tm2.tm_sec &&
              tm1.tm_min == tm2.tm_min &&
              tm1.tm_hour == tm2.tm_hour &&
              tm1.tm_mday == tm2.tm_mday &&
              tm1.tm_mon == tm2.tm_mon &&
              tm1.tm_year == tm2.tm_year &&
              tm1.tm_isdst == tm2.tm_isdst);
  }
  
  inline bool operator!=(const std::tm& tm1, const std::tm& tm2)
  {
      return !(tm1 == tm2);
  }
  
  // eol definition
  #if !defined (SPDLOG_EOL)
  #ifdef _WIN32
  #define SPDLOG_EOL "\r\n"
  #else
  #define SPDLOG_EOL "\n"
  #endif
  #endif
  
  SPDLOG_CONSTEXPR static const char* eol = SPDLOG_EOL;
  SPDLOG_CONSTEXPR static int eol_size = sizeof(SPDLOG_EOL) - 1;
  
  
  
  //fopen_s on non windows for writing
  inline int fopen_s(FILE** fp, const filename_t& filename, const filename_t& mode)
  {
  #ifdef _WIN32
  #ifdef SPDLOG_WCHAR_FILENAMES
      *fp = _wfsopen((filename.c_str()), mode.c_str(), _SH_DENYWR);
  #else
      *fp = _fsopen((filename.c_str()), mode.c_str(), _SH_DENYWR);
  #endif
      return *fp == nullptr;
  #else
      *fp = fopen((filename.c_str()), mode.c_str());
      return *fp == nullptr;
  #endif
  }
  
  inline int remove(const filename_t &filename)
  {
  #if defined(_WIN32) && defined(SPDLOG_WCHAR_FILENAMES)
      return _wremove(filename.c_str());
  #else
      return std::remove(filename.c_str());
  #endif
  }
  
  inline int rename(const filename_t& filename1, const filename_t& filename2)
  {
  #if defined(_WIN32) && defined(SPDLOG_WCHAR_FILENAMES)
      return _wrename(filename1.c_str(), filename2.c_str());
  #else
      return std::rename(filename1.c_str(), filename2.c_str());
  #endif
  }
  
  
  //Return if file exists
  inline bool file_exists(const filename_t& filename)
  {
  #ifdef _WIN32
  #ifdef SPDLOG_WCHAR_FILENAMES
      auto attribs = GetFileAttributesW(filename.c_str());
  #else
      auto attribs = GetFileAttributesA(filename.c_str());
  #endif
      return (attribs != INVALID_FILE_ATTRIBUTES && !(attribs & FILE_ATTRIBUTE_DIRECTORY));
  #else //common linux/unix all have the stat system call
      struct stat buffer;
      return (stat (filename.c_str(), &buffer) == 0);
  #endif
  }
  
  
  
  
  //Return file size according to open FILE* object
  inline size_t filesize(FILE *f)
  {
      if (f == nullptr)
          throw spdlog_ex("Failed getting file size. fd is null");
  #ifdef _WIN32
      int fd = _fileno(f);
  #if _WIN64 //64 bits
      struct _stat64 st;
      if (_fstat64(fd, &st) == 0)
          return st.st_size;
  
  #else //windows 32 bits
      long ret = _filelength(fd);
      if (ret >= 0)
          return static_cast<size_t>(ret);
  #endif
  
  #else // unix
      int fd = fileno(f);
      //64 bits(but not in osx, where fstat64 is deprecated)
  #if !defined(__FreeBSD__) && !defined(__APPLE__) && (defined(__x86_64__) || defined(__ppc64__))
      struct stat64 st;
      if (fstat64(fd, &st) == 0)
          return static_cast<size_t>(st.st_size);
  #else // unix 32 bits or osx
      struct stat st;
      if (fstat(fd, &st) == 0)
          return static_cast<size_t>(st.st_size);
  #endif
  #endif
      throw spdlog_ex("Failed getting file size from fd", errno);
  }
  
  
  
  
  //Return utc offset in minutes or throw spdlog_ex on failure
  inline int utc_minutes_offset(const std::tm& tm = details::os::localtime())
  {
  
  #ifdef _WIN32
  #if _WIN32_WINNT < _WIN32_WINNT_WS08
      TIME_ZONE_INFORMATION tzinfo;
      auto rv = GetTimeZoneInformation(&tzinfo);
  #else
      DYNAMIC_TIME_ZONE_INFORMATION tzinfo;
      auto rv = GetDynamicTimeZoneInformation(&tzinfo);
  #endif
      if (rv == TIME_ZONE_ID_INVALID)
          throw spdlog::spdlog_ex("Failed getting timezone info. ", errno);
  
      int offset = -tzinfo.Bias;
      if (tm.tm_isdst)
          offset -= tzinfo.DaylightBias;
      else
          offset -= tzinfo.StandardBias;
      return offset;
  #else
  
  #if defined(sun) || defined(__sun)
      // 'tm_gmtoff' field is BSD extension and it's missing on SunOS/Solaris
      struct helper
      {
          static long int calculate_gmt_offset(const std::tm & localtm = details::os::localtime(), const std::tm & gmtm = details::os::gmtime())
          {
              int local_year = localtm.tm_year + (1900 - 1);
              int gmt_year = gmtm.tm_year + (1900 - 1);
  
              long int days = (
                                  // difference in day of year
                                  localtm.tm_yday - gmtm.tm_yday
  
                                  // + intervening leap days
                                  + ((local_year >> 2) - (gmt_year >> 2))
                                  - (local_year / 100 - gmt_year / 100)
                                  + ((local_year / 100 >> 2) - (gmt_year / 100 >> 2))
  
                                  // + difference in years * 365 */
                                  + (long int)(local_year - gmt_year) * 365
                              );
  
              long int hours = (24 * days) + (localtm.tm_hour - gmtm.tm_hour);
              long int mins = (60 * hours) + (localtm.tm_min - gmtm.tm_min);
              long int secs = (60 * mins) + (localtm.tm_sec - gmtm.tm_sec);
  
              return secs;
          }
      };
  
      long int offset_seconds = helper::calculate_gmt_offset(tm);
  #else
      long int offset_seconds = tm.tm_gmtoff;
  #endif
  
      return static_cast<int>(offset_seconds / 60);
  #endif
  }
  
  //Return current thread id as size_t
  //It exists because the std::this_thread::get_id() is much slower(espcially under VS 2013)
  inline size_t _thread_id()
  {
  #ifdef _WIN32
      return  static_cast<size_t>(::GetCurrentThreadId());
  #elif __linux__
  # if defined(__ANDROID__) && defined(__ANDROID_API__) && (__ANDROID_API__ < 21)
  #  define SYS_gettid __NR_gettid
  # endif
      return  static_cast<size_t>(syscall(SYS_gettid));
  #elif __FreeBSD__
      long tid;
      thr_self(&tid);
      return static_cast<size_t>(tid);
  #else //Default to standard C++11 (OSX and other Unix)
      return static_cast<size_t>(std::hash<std::thread::id>()(std::this_thread::get_id()));
  #endif
  }
  
  //Return current thread id as size_t (from thread local storage)
  inline size_t thread_id()
  {
  #if defined(_MSC_VER) && (_MSC_VER < 1900) || defined(__clang_major__) && (__clang_major__ < 8)
      return _thread_id();
  #else
      static thread_local const size_t tid = _thread_id();
      return tid;
  #endif
  }
  
  
  
  
  // wchar support for windows file names (SPDLOG_WCHAR_FILENAMES must be defined)
  #if defined(_WIN32) && defined(SPDLOG_WCHAR_FILENAMES)
  #define SPDLOG_FILENAME_T(s) L ## s
  inline std::string filename_to_str(const filename_t& filename)
  {
      std::wstring_convert<std::codecvt_utf8<wchar_t>, wchar_t> c;
      return c.to_bytes(filename);
  }
  #else
  #define SPDLOG_FILENAME_T(s) s
  inline std::string filename_to_str(const filename_t& filename)
  {
      return filename;
  }
  #endif
  
  
  // Return errno string (thread safe)
  inline std::string errno_str(int err_num)
  {
      char buf[256];
      SPDLOG_CONSTEXPR auto buf_size = sizeof(buf);
  
  #ifdef _WIN32
      if(strerror_s(buf, buf_size, err_num) == 0)
          return std::string(buf);
      else
          return "Unkown error";
  
  #elif defined(__FreeBSD__) || defined(__APPLE__) || defined(ANDROID) || defined(__SUNPRO_CC) || \
        ((_POSIX_C_SOURCE >= 200112L) && ! defined(_GNU_SOURCE)) // posix version
  
      if (strerror_r(err_num, buf, buf_size) == 0)
          return std::string(buf);
      else
          return "Unkown error";
  
  #else  // gnu version (might not use the given buf, so its retval pointer must be used)
      return std::string(strerror_r(err_num, buf, buf_size));
  #endif
  }
  
  inline int pid()
  {
  
  #ifdef _WIN32
      return ::_getpid();
  #else
      return static_cast<int>(::getpid());
  #endif
  
  }
  
  } //os
  } //details
  } //spdlog
  