Door Lock - CC Sensor

-- When this program gets a redstone signal, it
-- scans for players. It continues scanning until
-- the redstone has been off for the configured
-- number of seconds.
--
-- While scanning, users on the whitelist will
-- cause a redstone signal to be emitted. Users on
-- the blacklist will prevent the redstone from
-- activating, even when whitelisted players are
-- near.
--
-- Author: MyrddinE
-- 2013-10-16

-- Configuration
local side = {sensor="bottom",input="right",output="back"}
local active_when = true
local open_emit = false
local continue_for = 30 -- seconds

local file = fs.open("whitelist.dat","r")
local whitelist = textutils.unserialize(file.readAll())
file.close()

file = fs.open("blacklist.dat","r")
local blacklist = textutils.unserialize(file.readAll())
file.close()

function roomOpen(open)
  if open then
    print("Opening door.")
  else
    print("Closing door.")
  end

  -- The '(open == open_emit)' is a logical filter, setting
  -- the output based on whether open = true, or open = false.
  rs.setOutput(side.output,(open == open_emit))
end

-- Load sensor api, and connect to it.
os.loadAPI("ocs/apis/sensor")
local players = sensor.wrap(side.sensor)

roomOpen(false)

-- Infinite loop waiting for redstone change.
while true do
  os.pullEvent("redstone")

  -- Initially just wait for 1 second when it
  -- detects a redstone change on any side.
  local stopTime = os.clock() + 1

  while os.clock() < stopTime do
    -- If the input side is in 'on mode' (as defined
    -- by the active_when var) then set the end time
    -- to be now + continue_for seconds (default of
    -- 30 seconds).
    if rs.getInput(side.input) == active_when then stopTime = os.clock() + continue_for end

    -- Compare all the names of nearby players to the
    -- lists.
    good = false
    bad = false
    targets = players.getTargets()
    for username,_ in pairs(targets) do
      write(username.." is ")
      if whitelist[username] then
        write("whitelisted. ")
        good = true
      elseif blacklist[username] then
        write("blacklisted. ")
        bad = true
      else
        write("unknown player. ")
      end
    end

    -- Open/close the door based on nearby listed
    -- players
    if bad then
      roomOpen(false)
    elseif good then
      roomOpen(true)
    else
      roomOpen(false)
    end

    write(os.time().." ")
    sleep(1)
  end

  -- Rebooting when the detection turns off allows dynamic
  -- re-loading of the software when updated.
  os.reboot()
end