Module:Gutenberg

local p = {}
 
function p.author(frame)
  
  local pframe = frame:getParent()
  local args = pframe.args
 
  local tname = "Gutenberg author" -- name of calling template. Change if template is renamed.
 
  local id       = nil -- author name, or author number. The later will go direct to the author page, the former to a search results page.
  local name     = nil -- display name on Wikipedia (default: article title)
  local url      = nil
  local tagline  = "at [[Project Gutenberg]]"
  local urlheadname  = "//www.gutenberg.org/author/"
  local urlheadnumb  = "//www.gutenberg.org/ebooks/author/"
  local urlhead  = nil

  if args.id == "" or args.id == nil then
    return error("Parameter id is missing. See [[Template:" .. tname .. "]] documentation")
  else
    id = mw.text.trim(args.id)
    if tonumber(id) ~= nil then -- it's a number
      urlhead = urlheadnumb
    else
      urlhead = urlheadname
    end
  end 

  if args.name == "" or args.name == nil then
    name = mw.title.getCurrentTitle().basePageTitle
  else
    name = mw.text.trim(args.name)
  end

  url = "[" .. urlhead .. id .. " Works by " .. name .. "] " .. tagline

  return url

end

return p
Usage
