text: // Copyright(c) 2015-present, Gabi Melman & spdlog contributors.
  // Distributed under the MIT License (http://opensource.org/licenses/MIT)
  
  #pragma once
  
  #ifndef SPDLOG_HEADER_ONLY
  #include <spdlog/details/file_helper.h>
  #endif
  
  #include <spdlog/details/os.h>
  #include <spdlog/common.h>
  
  #include <cerrno>
  #include <chrono>
  #include <cstdio>
  #include <string>
  #include <thread>
  #include <tuple>
  
  namespace spdlog {
  namespace details {
  
  SPDLOG_INLINE file_helper::~file_helper()
  {
      close();
  }
  
  SPDLOG_INLINE void file_helper::open(const filename_t &fname, bool truncate)
  {
      close();
      filename_ = fname;
      auto *mode = truncate ? SPDLOG_FILENAME_T("wb") : SPDLOG_FILENAME_T("ab");
  
      for (int tries = 0; tries < open_tries_; ++tries)
      {
          // create containing folder if not exists already.
          os::create_dir(os::dir_name(fname));
          if (!os::fopen_s(&fd_, fname, mode))
          {
              return;
          }
  
          details::os::sleep_for_millis(open_interval_);
      }
  
      SPDLOG_THROW(spdlog_ex("Failed opening file " + os::filename_to_str(filename_) + " for writing", errno));
  }
  
  SPDLOG_INLINE void file_helper::reopen(bool truncate)
  {
      if (filename_.empty())
      {
          SPDLOG_THROW(spdlog_ex("Failed re opening file - was not opened before"));
      }
      this->open(filename_, truncate);
  }
  
  SPDLOG_INLINE void file_helper::flush()
  {
      std::fflush(fd_);
  }
  
  SPDLOG_INLINE void file_helper::close()
  {
      if (fd_ != nullptr)
      {
          std::fclose(fd_);
          fd_ = nullptr;
      }
  }
  
  SPDLOG_INLINE void file_helper::write(const memory_buf_t &buf)
  {
      size_t msg_size = buf.size();
      auto data = buf.data();
      if (std::fwrite(data, 1, msg_size, fd_) != msg_size)
      {
          SPDLOG_THROW(spdlog_ex("Failed writing to file " + os::filename_to_str(filename_), errno));
      }
  }
  
  SPDLOG_INLINE size_t file_helper::size() const
  {
      if (fd_ == nullptr)
      {
          SPDLOG_THROW(spdlog_ex("Cannot use size() on closed file " + os::filename_to_str(filename_)));
      }
      return os::filesize(fd_);
  }
  
  SPDLOG_INLINE const filename_t &file_helper::filename() const
  {
      return filename_;
  }
  
  //
  // return file path and its extension:
  //
  // "mylog.txt" => ("mylog", ".txt")
  // "mylog" => ("mylog", "")
  // "mylog." => ("mylog.", "")
  // "/dir1/dir2/mylog.txt" => ("/dir1/dir2/mylog", ".txt")
  //
  // the starting dot in filenames is ignored (hidden files):
  //
  // ".mylog" => (".mylog". "")
  // "my_folder/.mylog" => ("my_folder/.mylog", "")
  // "my_folder/.mylog.txt" => ("my_folder/.mylog", ".txt")
  SPDLOG_INLINE std::tuple<filename_t, filename_t> file_helper::split_by_extension(const filename_t &fname)
  {
      auto ext_index = fname.rfind('.');
  
      // no valid extension found - return whole path and empty string as
      // extension
      if (ext_index == filename_t::npos || ext_index == 0 || ext_index == fname.size() - 1)
      {
          return std::make_tuple(fname, filename_t());
      }
  
      // treat cases like "/etc/rc.d/somelogfile or "/abc/.hiddenfile"
      auto folder_index = fname.rfind(details::os::folder_sep);
      if (folder_index != filename_t::npos && folder_index >= ext_index - 1)
      {
          return std::make_tuple(fname, filename_t());
      }
  
      // finally - return a valid base and extension tuple
      return std::make_tuple(fname.substr(0, ext_index), fname.substr(ext_index));
  }
  
  } // namespace details
  } // namespace spdlog
  