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



local default_error_category = "[[Category:Pages using infobox television with nonstandard dates]]"



local p = {}



function p.start_end_date_template_validation(frame)

	local args = getArgs(frame)

	local error_category = args.error_category or default_error_category



	local start_date = args.first_aired or args.released or args.airdate or args.release_date or args.airdate_overall

	if start_date then

		if not start_date:find("dtstart") then

			return error_category

		end

	end



	local end_date = args.last_aired

	if end_date then

		if not end_date:find("dtend") and end_date ~= "present" then

			return error_category

		end

	end

end



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;–<br />'

	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=MONTHSm2], day=d2, hour=0, min=0, sec=0}) - os.time({year=y1, month=MONTHSm1], 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