Help with timer/time in LUA script

[admin]

Create a scheduled scripts that runs every minute.
Change group addresses as needed:
1/1/1 - mode (2 = auto)
1/1/2 - forecast (true/false)
1/1/3 - temperature value
1/1/4 - output control

To simplify things the output will turn on at 0 minutes of every hour if needed and will turn off after X minutes depending on the current temperature.

Code:

mode = grp.getvalue('1/1/1')
if mode ~= 2 then
  return
end

forecast = grp.getvalue('1/1/2')
temperature = grp.getvalue('1/1/3')
if not forecast or temperature > 4 then
  offtime = 0
-- 0..4
elseif temperature >= 0 then
  offtime = 25
-- -4..0
elseif temperature >= -4 then
  offtime = 35
-- -8..-4
elseif temperature >= -8 then
  offtime = 50
-- lower than -8
else
  offtime = 60
end

min = os.date('*t').min
value = min < offtime
grp.checkwrite('1/1/4', value)