Module:Navbox with collapsible groups

-- This module implements {{Navbox with collapsible groups}}
local q = {}
local Navbox = require('Module:Navbox')

-- helper functions
local function concatstrings(s)
 local r = table.concat(s, '')
 if r:match('^%s*$') then r = nil end
 return r
end

local function concatstyles(s)
 local r = table.concat(s, ';')
 while r:match(';%s*;') do
  r = mw.ustring.gsub(r, ';%s*;', ';')
 end
 if r:match('^%s*;%s*$') then r = nil end
 return r
end

function q._navbox(pargs)
 -- table for args passed to navbox
 local targs = {}

 -- process args
 local passthrough = {
  ['name']=true,['navbar']=true,['state']=true,['border']=true,
  ['bodyclass']=true,['groupclass']=true,['listclass']=true,
  ['style']=true,['bodystyle']=true,['basestyle']=true,
  ['title']=true,['titleclass']=true,['titlestyle']=true,
  ['above']=true,['aboveclass']=true,['abovestyle']=true,
  ['below']=true,['belowclass']=true,['belowstyle']=true,
  ['image']=true,['imageclass']=true,['imagestyle']=true,
  ['imageleft']=true,['imageleftstyle']=true
 }
 for k,v in pairs(pargs) do
  if k and type(k) == 'string' then
   if passthrough[k] then
    targs[k] = v
   elseif (k:match('^list[0-9][0-9]*$') 
     or k:match('^content[0-9][0-9]*$') ) then
    local n = mw.ustring.gsub(k, '^[a-z]*([0-9]*)$', '%1')
    if (targs['list' .. n] == nil and pargs['group' .. n] == nil
     and pargs['sect' .. n] == nil and pargs['section' .. n] == nil) then
     targs['list' .. n] = concatstrings(
      {pargs['list' .. n] or '', pargs['content' .. n] or ''})
    end
   elseif (k:match('^group[0-9][0-9]*$') 
     or k:match('^sect[0-9][0-9]*$') 
     or k:match('^section[0-9][0-9]*$') ) then
    local n = mw.ustring.gsub(k, '^[a-z]*([0-9]*)$', '%1')
    if targs['list' .. n] == nil then
     local titlestyle = concatstyles(
      {pargs['groupstyle'] or '',pargs['secttitlestyle'] or '', 
       pargs['group' .. n .. 'style'] or '', 
       pargs['section' .. n ..'titlestyle'] or ''})
     local liststyle = concatstyles(
      {pargs['liststyle'] or '', pargs['contentstyle'] or '', 
       pargs['list' .. n .. 'style'] or '', 
       pargs['content' .. n .. 'style'] or ''})
     local title = concatstrings(
      {pargs['group' .. n] or '', 
       pargs['sect' .. n] or '',
       pargs['section' .. n] or ''})
     local list = concatstrings(
      {pargs['list' .. n] or '', 
       pargs['content' .. n] or ''})
     local state = (pargs['abbr' .. n] and pargs['abbr' .. n] == pargs['selected']) 
      and 'uncollapsed' or pargs['state' .. n] or 'collapsed'
     
     targs['list' .. n] = Navbox._navbox(
      {'child', navbar = 'plain', state = state,
      basestyle = pargs['basestyle'],
      title = title, titlestyle = titlestyle,
      list1 = list, liststyle = liststyle,
      listclass = pargs['list' .. n .. 'class'],
      image = pargs['image' .. n],
      imageleft = pargs['imageleft' .. n],
      listpadding = pargs['listpadding']})
    end
   end
  end
 end
 -- ordering of style and bodystyle
 targs['style'] = concatstyles({targs['style'] or '', targs['bodystyle'] or ''})
 targs['bodystyle'] = nil
 
 -- child or subgroup
 if targs['border'] == nil then targs['border'] = pargs[1] end

 return Navbox._navbox(targs)
end

function q.navbox(frame)
 local pargs = require('Module:Arguments').getArgs(frame, {wrappers = {'Template:Navbox with collapsible groups'}})

 -- Read the arguments in the order they'll be output in, to make references number in the right order.
 local _
 _ = pargs.title
 _ = pargs.above
 for i = 1, 20 do
  _ = pargs["group" .. tostring(i)]
  _ = pargs["list" .. tostring(i)]
 end
 _ = pargs.below

 return q._navbox(pargs)
end

return q