Get diff in seconds from now to date time

--[[
Get diff in seconds from now to date time by
Laurea
Foereaper
Rochet2
]]

local d = os.date("*t")

-- Set desired time here
d.sec = 0
d.min = 30
d.hour = 15
-- 1 = mon, 2 = tue ..
local weekday = 2

local ddiff = weekday-d.wday+1
d.day = d.day+ddiff
local now = os.date("*t")
if (ddiff < 0) then
-- Take into consideration that it is tuesday and we want monday
    d.day = d.day+7
elseif (ddiff == 0 and d.hour*60*60+d.min*60+d.sec < now.hour*60*60+now.min*60+now.sec) then
-- Take into consideration that it is the same date, but its already past the wanted time
    d.day = d.day+7
end
-- get final times
local e = os.time(d)
local diff = e-os.time() -- this is the time in seconds until the wanted date is achieved

-- test print
print(os.date("%c", os.time()+diff))
print(os.date("%c"))