////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 2001-2022 The Octave Project Developers
//
// See the file COPYRIGHT.md in the top-level directory of this
// distribution or <https://octave.org/copyright/>.
//
// This file is part of Octave.
//
// Octave is free software: you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Octave is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Octave; see the file COPYING.  If not, see
// <https://www.gnu.org/licenses/>.
//
////////////////////////////////////////////////////////////////////////

#if defined (HAVE_CONFIG_H)
#  include "config.h"
#endif

#include <deque>
#include <fstream>

#include "file-info.h"
#include "file-stat.h"
#include "lo-error.h"
#include "lo-sysdep.h"

namespace octave
{
  std::string file_info::get_line (std::size_t line) const
  {
    std::string retval;

    if (line == 0)
      return retval;

    if (line < m_offsets.size ())
      {
        std::size_t bol = m_offsets[line-1];
        std::size_t eol = m_offsets[line];

        while (eol > 0 && eol > bol
               && (m_file_buf[eol-1] == '\n' || m_file_buf[eol-1] == '\r'))
          eol--;

        retval = m_file_buf.substr (bol, eol - bol);
      }

    return retval;
  }

  std::deque<std::string>
  file_info::get_lines (std::size_t line, std::size_t num_lines) const
  {
    std::deque<std::string> retval;

    for (std::size_t i = line; i < line+num_lines; i++)
      retval.push_back (get_line (i));

    return retval;
  }

  // Read entire file called fname and return the contents as a string

  std::string file_info::snarf_file (const std::string& fname)
  {
    std::string retval;

    sys::file_stat fs (fname);

    if (! fs)
      (*current_liboctave_error_handler) ("no such file, '%s'", fname.c_str ());

    std::size_t sz = fs.size ();

    std::ifstream file = sys::ifstream (fname.c_str (),
                                        std::ios::in | std::ios::binary);

    if (file)
      {
        std::string buf (sz+1, 0);

        file.read (&buf[0], sz+1);

        if (! file.eof ())
          (*current_liboctave_error_handler)
            ("error reading file %s", fname.c_str ());

        // Expected to read the entire file.
        retval = buf;
      }

    return retval;
  }

  std::vector<std::size_t> file_info::get_line_offsets (const std::string& buf)
  {
    std::deque<std::size_t> tmp_offsets;

    tmp_offsets.push_back (0);

    std::size_t len = buf.length ();

    for (std::size_t i = 0; i < len; i++)
      {
        char c = buf[i];

        if (c == '\r' && ++i < len)
          {
            c = buf[i];

            if (c == '\n')
              tmp_offsets.push_back (i+1);
            else
              tmp_offsets.push_back (i);
          }
        else if (c == '\n')
          tmp_offsets.push_back (i+1);
      }

    tmp_offsets.push_back (len-1);

    std::size_t n = tmp_offsets.size ();

    std::vector<std::size_t> retval (n);
    std::size_t i = 0;
    for (auto& elt : tmp_offsets)
      retval[i++] = elt;

    return retval;
  }
}