local p = {}

local getArgs = require('Module:Arguments').getArgs



--args: 1 - ustring pattern, 2 - value if present, 3 - value if absent, 

--      page - page to test if not this page



function p._main(args)

	if not args"page" then

		args.page = mw.title.getCurrentTitle().fullText

	end

	local page = mw.title.new(args.page)

	if not page then

		--bad title

		return args"3" or ""

	end

	local content = page:getContent()

	if not content then

		--page does not exist

		return args"3" or ""

	end

	if mw.ustring.match(content, args"1" or "") then

		if args"sub" then

			--return value should have capture groups substed in

			local pattern = args"1" or ""

			if mw.ustring.sub(pattern, 1, 1) ~= "^" then

				--pattern does not force it to be at start of page

				pattern = "^.-" .. pattern

			end

			if mw.ustring.sub(pattern, -1) ~= "$" then

				--pattern does not force it to be at end of page

				pattern = pattern .. ".*$"

			end

			--pattern will now match entire content, so running gsub will

			--return the string that has been passed in parameter 2 with things

			--like %1 substituted, NOTE: %0 does not work in this

			local out = mw.ustring.gsub(content, pattern, args"2" or "")

			return out

		else

			return args"2" or ""

		end

	else

		return args"3" or ""

	end

end



function p.main(frame)

	local args = getArgs(frame)

	return p._main(args)

end



return p