Module:Template translation

local p = {}

function p.renderTranslatedTemplate(frame)

   --[[ If on a translation subpage (like Foobar/de), this function renders
       a given template in the same language, if the translation is available.
       Otherwise, the template is rendered in its default language, without
       modification.
       This is aimed at replacing the current implementation of Template:TNT.
       ]]
   
   local template = frame.args['template']
   local langcode = '/en'
   local namespace = 'Template:'
   
   -- Get the last subpage
   local subpage = mw.title.getCurrentTitle().subpageText
   
   --[[ Check whether the template is actually in the Template namespace, or
       if we're transcluding a main-namespace page.
       (added for backward compatibility of Template:TNT)
       ]]
   local templateFullTitle = mw.title.new( template, 'Template' )
       if ( templateFullTitle.id == 0)
       then
           namespace=':'
       end
   
   --[[ If the subpage is a valid language code, check if a translation of the
       template exists in that language; if so, put it in langcode.
       Check first if there's an apostrophe, because they break the 
       isKnownLanguageTag function.
       ]]

   if (type (mw.ustring.match( subpage, "'" )) == nil )
   then
       if ( mw.language.isKnownLanguageTag( subpage ) )
       then
           local translation = mw.title.new( namespace..template..'/'..subpage )
           if ( translation.id ~= 0)
           then
               langcode='/'..subpage
           end
       end
   end

   -- Copy args pseudo-table to a proper table so we can feed it to expandTemplate
   local arguments = {}
   for k, v in pairs( frame.args ) do
       arguments[k] = v
   end

   -- Render the template
   return frame:expandTemplate{ title = namespace..template..langcode, args = arguments }
   

end

return p