% ----------------------------------------------------------------------------
% the XSIM package - modules module
% 
%   eXercise Sheets IMproved
% 
% ----------------------------------------------------------------------------
% Clemens Niederberger
% Web:    https://github.com/cgnieder/xsim
% E-Mail: contact@mychemistry.eu
% ----------------------------------------------------------------------------
% Copyright 2017 Clemens Niederberger
% 
% This work may be distributed and/or modified under the
% conditions of the LaTeX Project Public License, either version 1.3
% of this license or (at your option) any later version.
% The latest version of this license is in
%   http://www.latex-project.org/lppl.txt
% and version 1.3 or later is part of all distributions of LaTeX
% version 2005/12/01 or later.
% 
% This work has the LPPL maintenance status `maintained'.
% 
% The Current Maintainer of this work is Clemens Niederberger.
% ----------------------------------------------------------------------------
% If you have any ideas, questions, suggestions or bugs to report, please
% feel free to contact me.
% ----------------------------------------------------------------------------
%
% this is a pseudo module as it does the actual definitions for the whole
% module loading stuff; we do this so both packages `xsimverb' and `xsim' can
% use the `verbwrite' module
\RequirePackage{scrlfile}
\ExplSyntaxOn

\msg_new:nnn {xsim} {module-missing}
  {
    You've~ requested~ the~ xsim~ module~ `#1'~ but~ it~ appears~ to~
    be~ missing~ on~ your~ system.~ Maybe~ you've~ misspelled~ the~ name?~
    Loading~ the~ module~ will~ abort~ \msg_line_context:
  }

\msg_new:nnn {xsim} {loading-module}
  { Loading~ module~ `#1'~ ... }

\msg_new:nnn {xsim} {wrong-module-name}
  { The~ module~ file~ name~ is~ `#2'~ but~ it~ provides~ module~ `#1'. }

\msg_new:nnn {xsim} {forbidden-module}
  {
    You've~ requested~ the~ xsim~ module~ `modules'~ \msg_line_context: .~
  This~ module~ is~ a~ pseudo~ module~ which~ may~ not~ be~ loaded~ through~
  the~ module~ loading~ mechansim.
  }

% ----------------------------------------------------------------------------

\tl_const:Nn \c__xsim_module_extension_tl {code.tex}
\tl_const:Nn \c__xsim_module_prefix_tl    {xsim}

\seq_new:N \g__xsim_loaded_modules_seq
\prop_new:N \g__xsim_loaded_modules_prop

\cs_new_protected:Npn \xsim_load_modules:n #1
  { \clist_map_inline:nn {#1} { \xsim_load_module:n {##1} } }

\cs_new_protected:Npn \xsim_load_module:n #1
  {
    \tl_set:Nx \l_tmpa_tl { \tl_trim_spaces:n {#1} }
    \str_if_eq_x:nnTF { \l_tmpa_tl } {modules}
      { \msg_error:nn {xsim} {forbidden-module} }
      {  \__xsim_load_module:V \l_tmpa_tl }
  }

\cs_new_protected:Npn \__xsim_load_module:n #1
  {
    \xsim_if_module_loaded:nF {#1}
      {
        \xsim_if_module_exist:nTF {#1}
          {
            \__xsim_use_module_hook:nn {#1} {before}
            \msg_info:nnn {xsim} {loading-module} {#1}
            \@onefilewithoptions
              {\c__xsim_module_prefix_tl.#1}[][]
              \c__xsim_module_extension_tl
            \__xsim_use_module_hook:nn {#1} {after}
          }
          { \msg_error:nnn {xsim} {module-missing} {#1} }
      }
  }
\cs_generate_variant:Nn \__xsim_load_module:n { V }

\prg_new_conditional:Npnn \xsim_if_module_loaded:n #1 {p,T,F,TF}
  {
    \seq_if_in:NnTF \g__xsim_loaded_modules_seq {#1}
      { \prg_return_true: }
      { \prg_return_false: }
  }

\prg_new_conditional:Npnn \xsim_if_module_exist:n #1 {p,T,F,TF}
  {
    \file_if_exist:nTF
      {\c__xsim_module_prefix_tl.#1.\c__xsim_module_extension_tl}
      { \prg_return_true: }
      { \prg_return_false: }
  }

% --------------------------------------------------------------------------
% module hooks:
% #1: module
% #2: code
\cs_new_protected:Npn \xsim_after_module:nn #1#2
  {
    \xsim_if_module_loaded:nTF {#1}
      {#2}
      { \__xsim_add_to_module_hook:nnn {#1} {after} {#2} }
  }

% #1: module
% #2: code
\cs_new_protected:Npn \xsim_before_module:nn #1#2
  {
    \xsim_if_module_loaded:nF {#1}
      { \__xsim_add_to_module_hook:nnn {#1} {before} {#2} }
  }

% #1: module
% #2: hook name
% #3: code
\cs_new_protected:Npn \__xsim_add_to_module_hook:nnn #1#2#3
  {
    \xsim_if_module_loaded:nF {#1}
      {
        \tl_if_exist:cF {g__xsim_module_#1_#2_hook_tl}
          { \tl_new:c {g__xsim_module_#1_#2_hook_tl} }
        \tl_gput_right:cn {g__xsim_module_#1_#2_hook_tl} {#3}
      }
  }

% #1: module
% #2: hook name
\cs_new_protected:Npn \__xsim_use_module_hook:nn #1#2
  {
    \tl_if_exist:cT {g__xsim_module_#1_#2_hook_tl}
      {
        \tl_use:c {g__xsim_module_#1_#2_hook_tl}
        \tl_gclear:c {g__xsim_module_#1_#2_hook_tl}
      }
  }

% --------------------------------------------------------------------------

\tl_new:N \l__xsim_module_date_tl
\tl_new:N \l__xsim_module_version_tl

\tl_if_exist:NF \c_xsim_date_tl
  { \tl_set:Nx \l__xsim_module_date_tl {\c_xsimverb_date_tl} }
\tl_if_exist:NF \c_xsim_version_tl
  { \tl_set:Nx \l__xsim_module_version_tl {\c_xsimverb_version_tl} }

\AfterPackage*{xsim}
  {
    \tl_set:Nx \l__xsim_module_date_tl {\c_xsim_date_tl}
    \tl_set:Nx \l__xsim_module_version_tl {\c_xsim_version_tl}
  }
  
\cs_new_protected:Npn \__xsim_module:nn #1#2
  {
    \seq_gput_right:Nn \g__xsim_loaded_modules_seq {#1}
    \prop_gput:Nnn \g__xsim_loaded_modules_prop {#1} {#2}
    \str_if_eq_x:nnF
      {\c__xsim_module_prefix_tl.#1.\c__xsim_module_extension_tl}
      {\@currname.\@currext}
      {
        \msg_error:nnnxx {xsim} {wrong-module-name}
          {#1}
          {\@currname.\@currext}
      }
    \ProvidesFile
      {\c__xsim_module_prefix_tl.#1.\c__xsim_module_extension_tl}
      [
        \l__xsim_module_date_tl
        \c_space_tl
        v \l__xsim_module_version_tl
        \c_space_tl
        xsim~ module~ `#1'~ (#2)
      ]
  }
\cs_generate_variant:Nn \msg_error:nnnn {nnnx}

% --------------------------------------------------------------------------
% define a xsim module:
% #1: name
% #2: description
\NewDocumentCommand \XSIMmodule {mm} { \__xsim_module:nn {#1} {#2}
\ExplSyntaxOn }

% --------------------------------------------------------------------------
% style files
\NewDocumentCommand \xsimstyle   {sm}
  {
    \__xsim_module:nn {#2} {}
    \IfBooleanF {#1} { \ExplSyntaxOn }
  }

\cs_new_protected:Npn \xsim_style_options:nn #1#2
  { \keys_define:nn {xsim/#1} {#2} }

\NewDocumentCommand \loadxsimstyle {m} { \xsim_load_module:n {#1} }

% --------------------------------------------------------------------------
\tex_endinput:D