local p = {}

local introText = 'Note:  This discussion has been included in the '
local delsortRoot = '[[Wikipedia:WikiProject Deletion sorting'
local dateTime = os.date("!%H:%M, %e %B %Y (UTC)")

local function _error(msg)
	return mw.text.tag('strong', {['class']='error'}, 'Error in [[Template:Deletion sorting]]: ' .. msg)
end

local function _small(s)
	return mw.text.tag('small', {['class']='delsort-notice'}, s)
end

local function _single(cat, sig)
	return _small(introText..delsortRoot..'/'..cat..'|list of '..cat..'-related deletion discussions]]. '..sig)
end

function p.single(frame)
	local args = frame:getParent().args
	if not mw.ustring.match(args[1],'%S') then
		if frame.args.example then args[1] = frame.args.example else return _error('Category not specified.') end
	end
	return _single(args[1], args.sig or args[2] or dateTime)
end

function p.multi(frame)
	local args = {}
	local sig=dateTime
	for k, v in pairs(frame:getParent().args) do
		if mw.ustring.match(v,'%S') then
			if type(k) == 'number' then
				local title = mw.title.new(v)
				if title and title.rootText then
					table.insert(args, title.rootText)
				else
					return _error('Input contains forbidden characters.')
				end				
			elseif k:sub(0,3) == 'sig' then
				sig = v
			end
		end
	end

	if #args == 0 then
		if frame.args.example then args[1] = frame.args.example else return _error('Category not specified.') end
	end
	local outStr = 'Note:  This discussion has been included in the '
	if #args == 1 then
		return _single(args[1], sig)
	else
		outStr = outStr..delsortRoot..'|deletion sorting]] lists for the following topics: '
		for i = 1, #args do
			if i > 1 then
				if #args > 2 then outStr = outStr..', ' end
				if i == #args then outStr = outStr..' and ' end
			end
			outStr = outStr..delsortRoot..'/'..args[i]..'|'..args[i]..']]'
		end
		return _small(outStr..'. '..sig)
	end
end

return p