########################################################################
##
## Copyright (C) 2005-2022 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/>.
##
########################################################################

## -*- texinfo -*-
## @deftypefn  {} {} license
## @deftypefnx {} {} license inuse
## @deftypefnx {} {} license inuse @var{feature}
## @deftypefnx {} {} license ("inuse")
## @deftypefnx {} {@var{retval} =} license ("inuse")
## @deftypefnx {} {@var{retval} =} license ("test", @var{feature})
## @deftypefnx {} {@var{retval} =} license ("checkout", @var{feature})
## @deftypefnx {} {[@var{retval}, @var{errmsg}] =} license ("checkout", @var{feature})
## Get license information for Octave and Octave packages.
##
## GNU Octave is free software distributed under the GNU General Public
## License (GPL), and a license manager makes no sense.  This function is
## provided only for @sc{matlab} compatibility.
##
## When called with no extra input arguments, it returns the Octave license,
## otherwise the first input defines the operation mode and must be one of
## the following strings: @code{inuse}, @code{test}, and @code{checkout}.
## The optional @var{feature} argument can either be @qcode{"octave"} (core),
## or an Octave package.
##
## @table @asis
## @item @qcode{"inuse"}
## Returns a list of loaded features, i.e., octave and the list of loaded
## packages.  If an output is requested, it returns a struct array with
## the fields @qcode{"feature"}, and @qcode{"user"}.
##
## @item @qcode{"test"}
## Return true if the specified @var{feature} is installed, false otherwise.
##
## An optional third argument @qcode{"enable"} or @qcode{"disable"} is
## accepted but ignored.
##
## @item @qcode{"checkout"}
## Return true if the specified @var{feature} is installed, false otherwise.
## An optional second output will have an error message if a package is not
## installed.
##
## @end table
##
## @seealso{pkg, ver, version}
## @end deftypefn

function [retval, errmsg] = license (cmd, feature, toggle)

  if (nargin == 0)
    ## then only give information about Octave core
    retval = "GNU General Public License";
    return;
  endif

  [features, loaded] = get_all_features ();

  switch (tolower (cmd))
    case "inuse"
      features = features(loaded);

      if (nargin > 1)
        features = features(strcmp (features, feature));
      endif
      if (nargout == 0)
        printf ("%s\n", features{:});
      else
        retval = struct ("feature", features, "user", get_username ());
      endif

    case "test"
      if (nargin < 2)
        print_usage ();
      endif

      if (nargin > 2)
        ## We ignore the toggle argument because... what's the point?  We
        ## don't need a license management system on Octave.  This function
        ## will return true, even if anyone tries to disable a license.
        switch (tolower (toggle))
          case "enable"   # do nothing
          case "disable"  # do nothing
          otherwise       error ("license: TOGGLE must be enable or disable");
        endswitch
      endif

      retval = any (strcmp (features, feature));

    case "checkout"
      ## I guess we could have the checkout command load packages but it's not
      ## really the same thing.  The closest we have is simply to check if
      ## there is a package with the feature name, and give an error if not.

      if (nargin != 2)
        print_usage ();
      endif

      retval = any (strcmp (features, feature));
      errmsg = "";

      if (! retval)
        errmsg = ['No package named "' feature '" installed'];
      endif

    otherwise
      print_usage ();
  endswitch

endfunction

function username = get_username ()

  pw = getpwuid (getuid ());
  if (isstruct (pw))
    username = pw.name;
  else
    username = "octave_user";
  endif

endfunction

function [features, loaded] = get_all_features ()
  pkg_list = pkg ("list");
  features = {"octave", ...
              cellfun(@(x) x.name, pkg_list, "uniformoutput", false){:}};
  loaded = [true, cellfun(@(x) x.loaded, pkg_list)];
endfunction


%!assert (license (), "GNU General Public License")
%!assert ((license ("inuse", "octave")).feature, "octave")

%!shared list
%!test
%! list = pkg ("list");
%! for idx = 1: numel (list)
%!   name = list{idx}.name;
%!   if (list{idx}.loaded);
%!     assert ((license ("inuse", name)).feature, name);
%!   else
%!     rv = license ("inuse", name);
%!     assert (isstruct (rv));
%!     assert (all (isfield (rv, {"feature", "user"})));
%!   endif
%! endfor

%!assert (license ("test", "octave"), true)
%!assert (license ("test", "not_a_valid package name"), false)

%!test
%! for idx = 1: numel (list)
%!   assert (license ("test", list{idx}.name), true);
%! endfor

%!assert (license ("checkout", "octave"), true)

%!test
%! [s, e] = license ("checkout", "NOT_A_PACKAGE");
%! assert (e, 'No package named "NOT_A_PACKAGE" installed');

## Test input validation
%!error license ("not_inuse")
%!error license ("not_test", "octave", "enable")
%!error <TOGGLE must be enable or disable> license ("test", "octave", "invalid_toggle")