os.loadAPI("ocs/apis/sensor")

local playerInfo = {}
if fs.exists('players') then
  local fh = fs.open('players', 'r')
  playerInfo = textutils.unserialize(fh.readAll())
  fh.close()
end

function displayNames(players)
  local i = 1
  term.clear()
  for k, v in pairs(players) do
    term.setCursorPos(1, i)
    term.write(v)
    i = i + 1
  end
end

local s = sensor.wrap("left")

while true do
 targets = s.getTargets()
 for k, v in pairs(targets) do
   if v['Name'] == "Player" then
     playerInfo[k] = k
   end
 end
 displayNames(playerInfo)
 fh = fs.open('players', 'w')
 fh.write(textutils.serialize(playerInfo))
 fh.close()
 sleep(5)
end