/*

Copyright (C) 1996-2016 John W. Eaton

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
<http://www.gnu.org/licenses/>.

*/

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

#include <cerrno>
#include <cstdio>
#include <cstdlib>
#include <cstring>

#if (defined (OCTAVE_HAVE_WINDOWS_FILESYSTEM) && ! defined (OCTAVE_HAVE_POSIX_FILESYSTEM))
#  include <algorithm>
#endif

#include <iostream>
#include <vector>

#include "areadlink-wrapper.h"
#include "canonicalize-file-name-wrapper.h"
#include "dir-ops.h"
#include "file-ops.h"
#include "file-stat.h"
#include "gen-tempname-wrapper.h"
#include "oct-env.h"
#include "oct-locbuf.h"
#include "oct-passwd.h"
#include "quit.h"
#include "singleton-cleanup.h"
#include "stat-wrappers.h"
#include "str-vec.h"
#include "unistd-wrappers.h"

namespace octave
{
  namespace sys
  {
    file_ops *octave::sys::file_ops::instance = 0;

    bool
    octave::sys::file_ops::instance_ok (void)
    {
      bool retval = true;

      if (! instance)
        {
#if (defined (OCTAVE_HAVE_WINDOWS_FILESYSTEM) && ! defined (OCTAVE_HAVE_POSIX_FILESYSTEM))
          char system_dev_sep_char = ':';
          char system_dir_sep_char = '\\';
          std::string system_dir_sep_str = "\\";
#else
          char system_dev_sep_char = 0;
          char system_dir_sep_char = '/';
          std::string system_dir_sep_str = "/";
#endif
#if defined (OCTAVE_HAVE_WINDOWS_FILESYSTEM)
          std::string system_dir_sep_chars = "/\\";
#else
          std::string system_dir_sep_chars = system_dir_sep_str;
#endif

          instance = new file_ops (system_dev_sep_char, system_dir_sep_char,
                                   system_dir_sep_str, system_dir_sep_chars);

          if (instance)
            singleton_cleanup_list::add (cleanup_instance);
        }

      if (! instance)
        (*current_liboctave_error_handler)
          ("unable to create file_ops object!");

      return retval;
    }

    // The following tilde-expansion code was stolen and adapted from
    // readline.

    // The default value of tilde_additional_prefixes.  This is set to
    // whitespace preceding a tilde so that simple programs which do not
    // perform any word separation get desired behavior.
    static const char *default_prefixes[] = { " ~", "\t~", ":~", 0 };

    // The default value of tilde_additional_suffixes.  This is set to
    // whitespace or newline so that simple programs which do not perform
    // any word separation get desired behavior.
    static const char *default_suffixes[] = { " ", "\n", ":", 0 };

    // If non-null, this contains the address of a function that the
    // application wants called before trying the standard tilde
    // expansions.  The function is called with the text sans tilde, and
    // returns a malloc()'ed string which is the expansion, or a NULL
    // pointer if the expansion fails.
    octave::sys::file_ops::tilde_expansion_hook
      octave::sys::file_ops::tilde_expansion_preexpansion_hook = 0;

    // If non-null, this contains the address of a function to call if the
    // standard meaning for expanding a tilde fails.  The function is
    // called with the text (sans tilde, as in "foo"), and returns a
    // malloc()'ed string which is the expansion, or a NULL pointer if
    // there is no expansion.
    octave::sys::file_ops::tilde_expansion_hook
      octave::sys::file_ops::tilde_expansion_failure_hook = 0;

    // When non-null, this is a NULL terminated array of strings which are
    // duplicates for a tilde prefix.  Bash uses this to expand '=~' and
    // ':~'.
    string_vector octave::sys::file_ops::tilde_additional_prefixes =
      default_prefixes;

    // When non-null, this is a NULL terminated array of strings which
    // match the end of a username, instead of just "/".  Bash sets this
    // to ':' and '=~'.
    string_vector octave::sys::file_ops::tilde_additional_suffixes =
      default_suffixes;

    // Find the start of a tilde expansion in S, and return the index
    // of the tilde which starts the expansion.  Place the length of the
    // text which identified this tilde starter in LEN, excluding the
    // tilde itself.

    static size_t
    tilde_find_prefix (const std::string& s, size_t& len)
    {
      len = 0;

      size_t s_len = s.length ();

      if (s_len == 0 || s[0] == '~')
        return 0;

      string_vector prefixes = octave::sys::file_ops::tilde_additional_prefixes;

      if (! prefixes.empty ())
        {
          for (size_t i = 0; i < s_len; i++)
            {
              for (int j = 0; j < prefixes.numel (); j++)
                {
                  size_t pfx_len = prefixes[j].length ();

                  if (prefixes[j] == s.substr (i, pfx_len))
                    {
                      len = pfx_len - 1;
                      return i + len;
                    }
                }
            }
        }

      return s_len;
    }

    // Find the end of a tilde expansion in S, and return the index
    // of the character which ends the tilde definition.

    static size_t
    tilde_find_suffix (const std::string& s)
    {
      size_t s_len = s.length ();

      string_vector suffixes = octave::sys::file_ops::tilde_additional_suffixes;

      size_t i = 0;

      for ( ; i < s_len; i++)
        {
          if (octave::sys::file_ops::is_dir_sep (s[i]))
            break;

          if (! suffixes.empty ())
            {
              for (int j = 0; j < suffixes.numel (); j++)
                {
                  size_t sfx_len = suffixes[j].length ();

                  if (suffixes[j] == s.substr (i, sfx_len))
                    return i;
                }
            }
        }

      return i;
    }

    // Take FNAME and return the tilde prefix we want expanded.

    static std::string
    isolate_tilde_prefix (const std::string& fname)
    {
      size_t f_len = fname.length ();

      size_t len = 1;

      while (len < f_len && ! octave::sys::file_ops::is_dir_sep (fname[len]))
        len++;

      return fname.substr (1, len);
    }

    // Do the work of tilde expansion on FILENAME.  FILENAME starts with a
    // tilde.

    static std::string
    tilde_expand_word (const std::string& filename)
    {
      size_t f_len = filename.length ();

      if (f_len == 0 || filename[0] != '~')
        return filename;

      // A leading '~/' or a bare '~' is *always* translated to the value
      // of $HOME or the home directory of the current user, regardless of
      // any preexpansion hook.

      if (f_len == 1 || octave::sys::file_ops::is_dir_sep (filename[1]))
        return octave::sys::env::get_home_directory () + filename.substr (1);

      std::string username = isolate_tilde_prefix (filename);

      size_t user_len = username.length ();

      std::string dirname;

      if (octave::sys::file_ops::tilde_expansion_preexpansion_hook)
        {
          std::string expansion
            = octave::sys::file_ops::tilde_expansion_preexpansion_hook (username);

          if (! expansion.empty ())
            return expansion + filename.substr (user_len+1);
        }

      // No preexpansion hook, or the preexpansion hook failed.  Look in the
      // password database.

      octave::sys::password pw = octave::sys::password::getpwnam (username);

      if (! pw)
        {
          // If the calling program has a special syntax for expanding tildes,
          // and we couldn't find a standard expansion, then let them try.

          if (octave::sys::file_ops::tilde_expansion_failure_hook)
            {
              std::string expansion
                = octave::sys::file_ops::tilde_expansion_failure_hook (username);

              if (! expansion.empty ())
                dirname = expansion + filename.substr (user_len+1);
            }

          // If we don't have a failure hook, or if the failure hook did not
          // expand the tilde, return a copy of what we were passed.

          if (dirname.empty ())
            dirname = filename;
        }
      else
        dirname = pw.dir () + filename.substr (user_len+1);

      return dirname;
    }

    bool
    octave::sys::file_ops::is_dev_sep (char c)
    {
#if (defined (OCTAVE_HAVE_WINDOWS_FILESYSTEM) && ! defined (OCTAVE_HAVE_POSIX_FILESYSTEM))
      return c == dev_sep_char ();
#else
      octave_unused_parameter (c);

      return false;
#endif
    }

    // If NAME has a leading ~ or ~user, Unix-style, expand it to the
    // user's home directory.  If no ~, or no <pwd.h>, just return NAME.

    std::string
    octave::sys::file_ops::tilde_expand (const std::string& name)
    {
      if (name.find ('~') == std::string::npos)
        return name;
      else
        {
          std::string result;

          size_t name_len = name.length ();

          // Scan through S expanding tildes as we come to them.

          size_t pos = 0;

          while (1)
            {
              if (pos > name_len)
                break;

              size_t len;

              // Make START point to the tilde which starts the expansion.

              size_t start = tilde_find_prefix (name.substr (pos), len);

              result.append (name.substr (pos, start));

              // Advance STRING to the starting tilde.

              pos += start;

              // Make FINI be the index of one after the last character of the
              // username.

              size_t fini = tilde_find_suffix (name.substr (pos));

              // If both START and FINI are zero, we are all done.

              if (! (start || fini))
                break;

              // Expand the entire tilde word, and copy it into RESULT.

              std::string tilde_word = name.substr (pos, fini);

              pos += fini;

              std::string expansion = tilde_expand_word (tilde_word);

              result.append (expansion);
            }

          return result;
        }
    }

    // A vector version of the above.

    string_vector
    octave::sys::file_ops::tilde_expand (const string_vector& names)
    {
      string_vector retval;

      int n = names.numel ();

      retval.resize (n);

      for (int i = 0; i < n; i++)
        retval[i] = tilde_expand (names[i]);

      return retval;
    }

    std::string
    octave::sys::file_ops::concat (const std::string& dir, const std::string& file)
    {
      return dir.empty ()
             ? file
             : (is_dir_sep (dir[dir.length ()-1])
                ? dir + file
                : dir + dir_sep_char () + file);
    }

    std::string
    octave::sys::file_ops::native_separator_path (const std::string& path)
    {
      std::string retval;

      if (dir_sep_char () == '/')
        retval = path;
      else
        {
          size_t n = path.length ();
          for (size_t i = 0; i < n; i++)
            {
              if (path[i] == '/')
                retval += dir_sep_char();
              else
                retval += path[i];
            }
        }

      return retval;
    }

    int
    mkdir (const std::string& nm, mode_t md)
    {
      std::string msg;
      return octave::sys::mkdir (nm, md, msg);
    }

    int
    mkdir (const std::string& name, mode_t mode, std::string& msg)
    {
      msg = "";

      int status = octave_mkdir_wrapper (name.c_str (), mode);

      if (status < 0)
        msg = std::strerror (errno);

      return status;
    }

    int
    mkfifo (const std::string& nm, mode_t md)
    {
      std::string msg;
      return mkfifo (nm, md, msg);
    }

    int
    mkfifo (const std::string& name, mode_t mode, std::string& msg)
    {
      msg = "";

      int status = octave_mkfifo_wrapper (name.c_str (), mode);

      if (status < 0)
        msg = std::strerror (errno);

      return status;
    }

    int
    link (const std::string& old_name, const std::string& new_name)
    {
      std::string msg;
      return link (old_name, new_name, msg);
    }

    int
    link (const std::string& old_name, const std::string& new_name,
          std::string& msg)
    {
      msg = "";

      int status = -1;

      status = octave_link_wrapper (old_name.c_str (), new_name.c_str ());

      if (status < 0)
        msg = std::strerror (errno);

      return status;
    }

    int
    symlink (const std::string& old_name, const std::string& new_name)
    {
      std::string msg;
      return symlink (old_name, new_name, msg);
    }

    int
    symlink (const std::string& old_name,
             const std::string& new_name, std::string& msg)
    {
      msg = "";

      int status = -1;

      status = octave_symlink_wrapper (old_name.c_str (), new_name.c_str ());

      if (status < 0)
        msg = std::strerror (errno);

      return status;
    }

    int
    readlink (const std::string& path, std::string& result)
    {
      std::string msg;
      return readlink (path, result, msg);
    }

    int
    readlink (const std::string& path, std::string& result, std::string& msg)
    {
      int status = -1;

      msg = "";

      char *buf = octave_areadlink_wrapper (path.c_str ());

      if (! buf)
        msg = std::strerror (errno);
      else
        {
          result = buf;
          ::free (buf);
          status = 0;
        }

      return status;
    }

    int
    rename (const std::string& from, const std::string& to)
    {
      std::string msg;
      return rename (from, to, msg);
    }

    int
    rename (const std::string& from, const std::string& to, std::string& msg)
    {
      int status = -1;

      msg = "";

      status = std::rename (from.c_str (), to.c_str ());

      if (status < 0)
        msg = std::strerror (errno);

      return status;
    }

    int
    rmdir (const std::string& name)
    {
      std::string msg;
      return rmdir (name, msg);
    }

    int
    rmdir (const std::string& name, std::string& msg)
    {
      msg = "";

      int status = -1;

      status = octave_rmdir_wrapper (name.c_str ());

      if (status < 0)
        msg = std::strerror (errno);

      return status;
    }

    // And a version that works recursively.

    int
    recursive_rmdir (const std::string& name)
    {
      std::string msg;
      return recursive_rmdir (name, msg);
    }

    int
    recursive_rmdir (const std::string& name, std::string& msg)
    {
      msg = "";

      int status = 0;

      octave::sys::dir_entry dir (name);

      if (dir)
        {
          string_vector dirlist = dir.read ();

          for (octave_idx_type i = 0; i < dirlist.numel (); i++)
            {
              octave_quit ();

              std::string nm = dirlist[i];

              // Skip current directory and parent.
              if (nm == "." || nm == "..")
                continue;

              std::string fullnm = name + octave::sys::file_ops::dir_sep_str () + nm;

              // Get info about the file.  Don't follow links.
              octave::sys::file_stat fs (fullnm, false);

              if (fs)
                {
                  if (fs.is_dir ())
                    {
                      status = recursive_rmdir (fullnm, msg);

                      if (status < 0)
                        break;
                    }
                  else
                    {
                      status = unlink (fullnm, msg);

                      if (status < 0)
                        break;
                    }
                }
              else
                {
                  msg = fs.error ();
                  break;
                }
            }

          if (status >= 0)
            {
              dir.close ();
              status = rmdir (name, msg);
            }
        }
      else
        {
          status = -1;

          msg = dir.error ();
        }

      return status;
    }

    int
    umask (mode_t mode)
    {
      return octave_umask_wrapper (mode);
    }

    int
    unlink (const std::string& name)
    {
      std::string msg;
      return unlink (name, msg);
    }

    int
    unlink (const std::string& name, std::string& msg)
    {
      msg = "";

      int status = -1;

      status = octave_unlink_wrapper (name.c_str ());

      if (status < 0)
        msg = std::strerror (errno);

      return status;
    }

    std::string
    tempnam (const std::string& dir, const std::string& pfx)
    {
      std::string msg;
      return tempnam (dir, pfx, msg);
    }

    std::string
    tempnam (const std::string& dir, const std::string& pfx,
             std::string& msg)
    {
      msg = "";

      std::string retval;

      // get dir path to use for template
      std::string templatename;
      if (dir.empty ())
        templatename = octave::sys::env::get_temp_directory ();
      else if (! octave::sys::file_stat (dir, false).is_dir ())
        templatename = octave::sys::env::get_temp_directory ();
      else
        templatename = dir;

      // add dir sep char if it is not there
      if (*templatename.rbegin () != octave::sys::file_ops::dir_sep_char ())
        templatename += octave::sys::file_ops::dir_sep_char ();

      if (pfx.empty ())
        templatename += "file";
      else
        templatename += pfx;

      // add the required XXXXXX for the template
      templatename += "XXXXXX";

      // create and copy template to char array for call to gen_tempname
      char tname [templatename.length () + 1];

      strcpy (tname, templatename.c_str ());

      if (octave_gen_tempname_wrapper (tname) == -1)
        msg = std::strerror (errno);
      else
        retval = tname;

      return retval;
    }

    std::string
    canonicalize_file_name (const std::string& name)
    {
      std::string msg;
      return canonicalize_file_name (name, msg);
    }

    std::string
    canonicalize_file_name (const std::string& name, std::string& msg)
    {
      msg = "";

      std::string retval;

      char *tmp = octave_canonicalize_file_name_wrapper (name.c_str ());

      if (tmp)
        {
          retval = tmp;
          free (tmp);
        }

#if (defined (OCTAVE_HAVE_WINDOWS_FILESYSTEM) && ! defined (OCTAVE_HAVE_POSIX_FILESYSTEM))
      // Canonical Windows file separator is backslash.
      std::replace (retval.begin (), retval.end (), '/', '\\');
#endif

      if (retval.empty ())
        msg = std::strerror (errno);

      return retval;
    }
  }
}