\ProvidesPackage{addtoluatexpath}[2024-03-14]

\RequirePackage{luacode}

\providecommand{\input@path}{} % initialize input@path if not defined yet

\begin{luacode*}
  
  atlp_paths = {"."} -- global table containing paths added by this package

  function atlp_find_file(f) -- find a path in list of atlp_paths
    for i, k in pairs(atlp_paths) do
      local fp = kpse.find_file(k ..'/'.. f)
      if (fp) then
        return fp
      end
    end -- if nothing returned, issue a package error
    texio.write_nl('addtoluatexpath searched for file: '..f)
    texio.write_nl('addtoluatexpath searched paths were: '..token.get_macro('input@path'))
    tex.sprint('\\PackageError{addtoluatexpath}{a file was not found}{}')
    tex.sprint('\\stop')
  end
  
  function atlp_main(atlp_raw) -- add to path from raw string

    local atlp_tbl = require'luakeys'().parse(atlp_raw, {naked_as_value=true}) -- paths as table

    local atlp_no_lua = atlp_tbl['nolua'] or false  -- check and set nolua=true
    local atlp_no_tex = atlp_tbl['notex'] or false  -- check and set notex=true

    if atlp_raw:find('*') ~= nil then  -- if *, must use penlight to expand subdirectories
      penlight = require'penlight'
      atlp_tbl = penlight.List(atlp_tbl) -- convert to pl.List for easy manipulation
    end

    for __, p in ipairs(atlp_tbl) do
      if p:find('*') == nil then -- add paths without *, and continue the loop after
        if not atlp_no_lua then package.path = package.path .. ';'..p..'/?.lua;' end
        if not atlp_no_tex then  token.set_macro('input@path', token.get_macro('input@path')..'{'..p..'/}', 'global') end
        atlp_paths[#atlp_paths + 1] = p -- append the added path to global list
        goto continue
      end

      local p, c  = p:gsub('*','') -- if * added, include subdirectories
      local atlp_subdirs = penlight.List(penlight.dir.getdirectories(p))
      -- troubleshooting --texio.write_nl(penlight.pretty.write(atlp_subdirs))
      if c == 2 then
        atlp_subdirs = atlp_subdirs:map(function(s) return s ..'/**'  end) -- add ** to subdirs for recursive inclusion
      end
      atlp_tbl:append(p) -- make sure p (current path without *) is still added!
      atlp_tbl:extend(atlp_subdirs) -- extend path to include additional subdirs; the for loop is lengthened

      ::continue::
    end

    -- -- troubleshooting: show all paths
    --texio.write_nl('Lua Paths >>> \n'..package.path:gsub(';','\n'))
    --texio.write_nl('TeX Paths >>> \n'..token.get_macro('input@path'):gsub('}{','\n'))

  end

  atlp_main(token.get_macro('@raw@opt@addtoluatexpath.sty'))

\end{luacode*}

\NewDocumentCommand{\addtoluatexpath}{m}{\luadirect{atlp_main(\luastring{#1})}}  % a command

\AtEndOfPackage{\let\@unprocessedoptions\relax}