crystal-growth.lua

local FILE_PATH = "storage.dat"
local SLEEP_WAIT = 60
local GROWTH_TIME = 8200 * 1000

function getLast()
    if not fs.exists(FILE_PATH) then
         return 0
    end

    local file = fs.open(FILE_PATH, "r")
    local contents = file.readAll()
    file.close()

    return tonumber(contents)
end

function setLast(value)
    local file = fs.open(FILE_PATH, "w")
    file.write("" .. value)
    file.close()
end

function iterate()
    print("[cr] waiting for growth ...")
    while (os.epoch("utc") - getLast()) < GROWTH_TIME do
        sleep(SLEEP_WAIT)
    end

    print("[cr] growth assumed to be finished!")
    setLast(os.epoch("utc"))
    redstone.setOutput("back", true)
    sleep(2)
    redstone.setOutput("back", false)
end

function main()
    print("\n\n-------------------------------")
    print("[cr] starting the program; v1.0")
    print("-------------------------------\n\n");

    while true do
        iterate()
    end
end

main()