Module:Vgrtbl

local p = {}

local lang = mw.language.getContentLanguage()

local function looksLikeYear(str)
	local success, result = pcall(lang.formatDate, lang, 'Y', '1-1-' .. str)
	return success and tonumber(result) == tonumber(str)
end

function p._text(dateText, name, v, s)
	local retval = '<span style="white-space:normal;">'
	local success, result = pcall(lang.formatDate, lang, 'c', dateText)
	if looksLikeYear(dateText) or not success then
		retval = retval .. dateText
	else
		if s then
			retval = retval .. '<span style="display:none">' .. lang:formatDate('Ym', dateText) .. '</span>'
		end
		local success2, result2 = pcall(lang.formatDate, lang, 'c', '1 ' .. dateText)
		if success2 and result == result2 then
			retval = retval .. lang:formatDate(v == '0' and 'Y-m' or 'F Y', dateText)
		else
			if s then
				retval = retval .. '<span style="display:none">' .. lang:formatDate('Ymd', dateText) .. '</span>'
			end
			local formatString
			if v == '0' then
				formatString = 'Y-m-d'
			elseif v == '2' then
				formatString = 'j F Y'
			else
				formatString = 'F j, Y'
			end
			retval = retval .. lang:formatDate(formatString, dateText)
		end
	end
	return retval .. '<small>&nbsp;(' .. name .. ')</small></span>'
end

function p.text(frame)
	local args = frame:getParent().args
	return p._text(args[1], args[2], args.v, args.s)
end

local function tryDate(str)
	local success, result = pcall(lang.formatDate, lang, 'c', str)
	if success then
		return result
	else
		return str
	end
end

function p.main(frame)
	local args = frame.args[1] and frame.args or frame:getParent().args
	local v = args.v or 1
	if args.c == '0' then
		-- If collapse mode is off
		local retval = p._text(args[2], args[1], v, 1)
		local i = 3
		while args[i] and mw.text.trim(args[i]) ~= '' do
			retval = retval .. '<br />' .. p._text(args[i + 1], args[i], v)
			i = i + 2
		end
		return retval
	else
		-- If collapse mode is on
		local dates = {}
		local dateOrder = {}
		local i = 1
		while args[i] and mw.text.trim(args[i]) ~= '' do
			local d = tryDate(args[i + 1])
			if dates[d] then
				table.insert(dates[d], args[i])
			else
				table.insert(dateOrder, d)
				dates[d] = { display = args[i + 1], args[i] }
			end
			i = i + 2
		end
		local retval = ''
		for key, val in ipairs(dateOrder) do
			if key == 1 then
				retval = p._text(dates[val].display, table.concat(dates[val], '/'), v, 1)
			else
				retval = retval .. '<br />' .. p._text(dates[val].display, table.concat(dates[val], '/'), v)
			end
		end
		return retval
	end
end

return p