Simple timer system for TPT Lua

require "socket"

local start_time = socket.gettime() * 1000
local timeouts = {}
local intervals = {}

local function step()
    -- calculate frame rate and delta
    local now = socket.gettime() * 1000
    local delta = (now - start_time) + 0.02
    start_time = now

    -- and process intervals and timeouts
    for i, v in ipairs(timeouts) do
        v.time = v.time - delta
        if v.time <= 0 then
            v.func(v.args)
            table.remove(timeouts, i)
        end
    end

    for i, v in ipairs(intervals) do
        v.time = v.time - delta
        if v.time <= 0 then
            v.func(v.args)
            v.time = v.start
        end
    end
end

-- Add a function to be called after x milliseconds.
-- Returns the id of the binding.
local function setTimeout(func, time, ...)
    d = {}
    d.func = func
    d.time = time
    d.args = ...
    table.insert(timeouts, d)
    return #timeouts
end

-- Add a function to be called every x milliseconds.
-- Returns the id of the binding.
local function setInterval(func, time, ...)
    d = {}
    d.func = func
    d.time = time
    d.start = time
    d.args = ...
    table.insert(intervals, d)
    return #intervals
end

-- Remove a function from being called.
-- Takes the function or the bindings id as the first argument.
-- If a function is given, you can pass the maximal number of bindings to be
-- removed as the second argument.
local function clearTimeout(id, n)
    if type(id) == "number" then
        if id > 0 and id <= #timeouts then
            table.remove(timeouts, id)
            return true
        else
            return false
        end
    else
        local ret = 0
        local n = n or 1

        for i, v in ipairs(timeouts) do
            if v == id then
                table.remove(timeouts, i)
                ret = ret + 1
                if ret >= n then
                    return ret
                end
            end
        end
        return 0
    end
end

-- Like clearTimeout but with intervals :P
local function clearInterval(id)
    if type(id) == "number" then
        if id > 0 and id <= #intervals then
            table.remove(intervals, id)
            return true
        else
            return false
        end
    else
        local ret = 0
        local n = n or 1

        for i, v in ipairs(intervals) do
            if v == id then
                table.remove(intervals, i)
                ret = ret + 1
                if ret >= n then
                    return ret
                end
            end
        end
        return 0
    end
end

-- EXAMPLE
tpt.register_step(step)

-- Count to three in 3 seconds
local n = 1
setInterval(function()
    print(n)
    n = n + 1
    if n > 3 then
        clearInterval(#intervals) -- clear the last one
    end
end, 1000)