Module:Library citation

local p = {}

function is_lib_work(s)
	return mw.getCurrentFrame():callParserFunction('#ifexist',"Library:" .. s,true) == "1"
end

local function checkset(var)
	local rtn = ""
	if not (var == nil or var == '') then
		rtn = var
	return rtn
	end
end

function listOfWorks(author) 
	local newMethod = mw.getCurrentFrame():callParserFunction("#dpl","namespace=Library","titleregexp=" .. author .. "/[^/]+$","format=,%PAGE%\\n")
	local catMethod = mw.getCurrentFrame():callParserFunction("#dpl","namespace=Library","category=Library works by " .. author ,"format=,%PAGE%\\n")
	local list = ""
	-- Picks whatever method of recovering pages has the higher count, usually categories
	if string.len(newMethod) > string.len(catMethod) then
		list = string.gsub(newMethod,"Library:" .. author,"")
		else
			list = string.gsub(catMethod,"Library:","")
	end
	return list
end

function p.cite(frame)
	-- Parent frame to get parameters from template calls instead of from {{#invoke: ...
	local parentFrame = frame:getParent()
	-- get arguments from "args" table pre-defined by MediaWiki/Scribunto
	local link = checkset(parentFrame.args.link)
	local author = checkset(parentFrame.args.author)
	-- error("error message") to send error messages
	-- mw.log(mw.getCurrentFrame():callParserFunction("#dpl","namespace=Library","titleregexp=Vladimir Lenin/[^/]+$","format=,%PAGE%\\n"))
	-- mw.log(mw.getCurrentFrame():callParserFunction("#dpl","namespace=Library","category=Library works by Vladimir Lenin","format=,%PAGE%\\n"))
	return listOfWorks(author)
end
return p