doorThing.lua

local ints = {peripheral.find("redstone_integrator")}
local mons = {peripheral.find("monitor")}
local openTime = 15
local scale = 4

local function forEachPeripheral(periphs, func)
  local x = {}
  for i, periph in ipairs(periphs) do
    table.insert(x, {func(periph, i)})
  end
  return x
end

local function turnOn()
  forEachPeripheral(
    ints,
    function(integrator)
      for i, side in ipairs(integrator.getSides()) do
        integrator.setOutput(side, true)
      end
    end
  )
end

local function turnOff()
  forEachPeripheral(
    ints,
    function(integrator)
      for i, side in ipairs(integrator.getSides()) do
        integrator.setOutput(side, false)
      end
    end
  )
end

local function writeMonitors(col1, col2, stuff)
  forEachPeripheral(
    mons,
    function(monitor)
      monitor.setBackgroundColor(col1 or colors.black)
      monitor.setTextColor(col2 or colors.white)
      monitor.clear()
      monitor.setTextScale(scale)
      monitor.setCursorPos(1, 1)
      monitor.write(stuff or "")
    end
  )
end

local function wait(tm)
  local tmr = os.startTimer(tm)
  while true do
    local ev, tmr2 = os.pullEventRaw()

    if ev == "terminate" then
      turnOff()
      error("Terminated", 0)
    elseif ev == "timer" and tmr == tmr2 then
      return
    end
  end
end

local function countDown()
  local sizes = forEachPeripheral(
    mons,
    function(monitor)
      return monitor.getSize()
    end
  )

  for i = openTime, 0, -1 do
    forEachPeripheral(
      mons,
      function(monitor, o)
        local mx, my = table.unpack(sizes[o])
        local ln = #tostring(i)
        local wrt = string.rep(' ', mx - ln) .. tostring(i)
        monitor.setBackgroundColor(colors.black)
        monitor.setTextColor(colors.white)
        monitor.clear()
        monitor.setCursorPos(1, 1)
        monitor.write(wrt)
      end
    )

    wait(1)
  end
end

local function open()
  writeMonitors(colors.red)
  print("Opening.")
  turnOn()
  parallel.waitForAny(
    function()
      wait(openTime)
    end,
    countDown
  )
  turnOff()
  writeMonitors(nil, nil, "DOORS")
end


local function main()
  turnOff()
  writeMonitors(nil, nil, "DOORS")
  while true do
    term.clear()
    term.setCursorPos(1, 1)
    print("Press 'o' to open.")
    local ev, key = os.pullEvent()
    if ev == "key" and key == keys.o then
      open()
    elseif ev == "monitor_touch" then
      open()
    end
  end
end

main()