/*
  ISC License

  Copyright (c) 2026, Antonio SJ Musumeci <trapexit@spawn.link>

  Permission to use, copy, modify, and/or distribute this software for any
  purpose with or without fee is hereby granted, provided that the above
  copyright notice and this permission notice appear in all copies.

  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/

#include "fs_readahead.hpp"

#include "fmt/core.h"
#include "fs_lstat.hpp"

#include <fstream>
#include <string>

#ifdef __FreeBSD__
# include <sys/types.h>
#else
# include <sys/sysmacros.h>
#endif


static
std::string
_generate_readahead_sys_path(cu64 major_,
                             cu64 minor_)
{
  return fmt::format("/sys/class/bdi/{}:{}/read_ahead_kb",major_,minor_);
}

int
fs::readahead(cu64 major_dev_,
              cu64 minor_dev_,
              cu64 size_in_kb_)
{
  std::string syspath;
  std::ofstream ofs;

  syspath = ::_generate_readahead_sys_path(major_dev_,minor_dev_);

  ofs.open(syspath);
  if(ofs)
    {
      ofs << fmt::format("{}\n",size_in_kb_);
      ofs.close();
    }

  return 0;
}

int
fs::readahead(cu64 dev_,
              cu64 size_in_kb_)
{
  u32 major_dev;
  u32 minor_dev;

  major_dev = major(dev_);
  minor_dev = minor(dev_);

  return fs::readahead(major_dev,minor_dev,size_in_kb_);
}

int
fs::readahead(const std::string path_,
              cu64               size_in_kb_)
{
  int rv;
  struct stat st;

  rv = fs::lstat(path_,&st);
  if(rv < 0)
    return rv;

  return fs::readahead(st.st_dev,size_in_kb_);
}