Elevator Server

local currentFloorNumber

function saveFloorNum(FloorNumber)

  local file = fs.open("floorNumber", "w")
  file.write(textutils.serialize(FloorNumber))
  file.close()

end

function readFloorNum()

  local FloorNumber

  if fs.exists("floorNumber") then
    local file = fs.open("floorNumber", "r")
    FloorNumber = textutils.unserialize(file.readAll())
  end

  return FloorNumber

end

if fs.exists("floorNumber") then
  currentFloorNumber = readFloorNum()
else
  currentFloorNumber = 1
end

local openModem = peripheral.find("modem") or error("No modem attached", 0)

openModem.open(6969)
openModem.open(6968)
openModem.open(6967)

print("opened")

local event, side, channel, replyChannel, message, distance
while true do
  event, side, channel, replyChannel, message, distance = os.pullEvent("modem_message")
  print(channel)
  print("Received a reply: " .. tostring(message))
  print("Current Floor is " .. currentFloorNumber)

  if channel == 6969 then

    currentFloorNumber = message
    saveFloorNum(currentFloorNumber)

  elseif channel == 6968 then

    redstone.setOutput("Top", true)
    os.sleep(1)
    redstone.setOutput("Top", false)

    if tonumber(message) < tonumber(currentFloorNumber) then
      openModem.transmit(tonumber(message), 0, "Up")
    elseif tonumber(message) > tonumber(currentFloorNumber) then
      openModem.transmit(tonumber(message), 0, "Down")
    end
    currentFloorNumber = message
    saveFloorNum(currentFloorNumber)

  end
end