Editing Module:Infobox/dates/sandbox

local getArgs = require('Module:Arguments').getArgs
local p = {}

function p.dates(frame)
	local returnval;
	local args = getArgs(frame);
	
	if table.getn(args) < 2 then
		if args['1'] == nil and args['2'] == nil then
			return '';
		elseif args['1'] == nil then 
			return args['2'];
		elseif args['2'] == nil then 
			return args['1'];
		end
	end
	
	args['1'] = args['1']:gsub("&nbsp;"," ");
	args['2'] = args['2']:gsub("&nbsp;"," ");
	
	local dmy = false;
	local pr1, m1, d1, y1, su1 = string.match(args['1'], '(.-)(%u%a+)%s(%d+),%s(%d+)(.*)');
	local pr2, m2, d2, y2, su2 = string.match(args['2'], '(.-)(%u%a+)%s(%d+),%s(%d+)(.*)');
	if y1 == nil then
		dmy = true;
		pr1, d1, m1, y1, su1 = string.match(args['1'], '(.-)(%d%d?)%s(%a+)%s(%d+)(.*)');
		pr2, d2, m2, y2, su2 = string.match(args['2'], '(.-)(%d%d?)%s(%a+)%s(%d+)(.*)');
	end
	
	local dash = '&nbsp;– ';
	if y1 ~= nil and y2 ~= nil then
		su1 = su1 or '';
		su2 = su2 or '';
		
		local MONTHS = {January=1, February=2, March=3, April=4, May=5, June=6, July=7, August=8, September=9, October=10, November=11, December=12};
		local diff = os.time({year=y2,month=MONTHS[m2],day=d2,hour=0,min=0,sec=0})-os.time({year=y1,month=MONTHS[m1],day=d1,hour=0,min=0,sec=0});
		
		if diff < 0 then
			returnval = 'Invalid date range';
		else
			if y1 == y2 then
				if dmy == false then
					returnval = pr1..m1..' '..d1..su1..dash..pr2..m2..' '..d2..', '..y2..su2;
				else
					returnval = pr1..d1..' '..m1..su1..dash..pr2..d2..' '..m2..' '..y2..su2;
				end
			else
				if dmy == false then
					returnval = pr1..m1..' '..d1..', '..y1..su1..dash..pr2..m2..' '..d2..', '..y2..su2;
				else
					returnval = pr1..d1..' '..m1..' '..y1..su1..dash..pr2..d2..' '..m2..' '..y2..su2;
				end
			end
		end
	else
		returnval = args['1']..dash..args['2'];
	end
	
	return returnval;
end

return p