local curfloor
local sel

local function loadOnStartup()
  local h = fs.open('.data', 'r') -- hidden file

  assert(h, "ERROR: Could not open data file in read mode.")

  local t1 = h.readLine()
  local t2 = h.readLine()
  h.close()

  if t1 then
    curfloor = t1
  end

  if t2 then
    sel = t2
  end
end

local function persistData()
  local h = fs.open('.data', 'w')

  assert(h, "ERROR: Could not open data file in write mode.")

  h.write(curfloor..'\n')
  h.write(sel)
  h.close()
end

local function setCurfloor(s)
  curfloor = s
  persistData()
end

local function setSel(s)
  sel = s
  persistData()
end

local function down(n)
  for i=1, n do
    rs.setBundledOutput("back", colors.white)
    sleep(.5)
    rs.setBundledOutput("back", 0)
    sleep(.5)
  end
end

local function up(u)
  for i=1, u do
    rs.setBundledOutput("back", colors.orange)
    sleep(.5)
    rs.setBundledOutput("back", 0)
    sleep(1)
  end
end

local function ground()
  print(sel)
  print(curfloor)

  if curfloor == sel then
    print("already here")
  else
    if curfloor == "second" then
      down(5)
      setCurfloor("ground")
    else
      down(22)
      setCurfloor("ground")
    end
  end
end

function second()
  print(sel)
  print(curfloor)

  if curfloor == sel then
    print("already here")
  else
    if curfloor == "ground" then
      up(5)
      setCurfloor("second")
    else
      down(17)
      setCurfloor("second")
    end
  end
end

function top()
  print(sel)
  print(curfloor)

  if curfloor == sel then
    print("already here")
  else
    if curfloor == "ground" then
      up(22)
      setCurfloor("mountain")
    else
      up(17)
      setCurfloor("mountain")
    end
  end
end

rednet.open("right") -- you want to be using channels if you are going to use 'modem_message' not rednet api


if fs.exists('.data') then
  loadOnStartup()
else
  curfloor = 'ground'
  sel = 'ground'
end

while true do
  local event, side, sendChannel, replyChannel, msg, distSent = os.pullEvent()

  if event == "modem_message" then
    setSel(msg)
    print(event)
    print(sel)
    if sel == "ground" then
      ground()
    elseif sel == "second" then
      second()
    else
      top()
    end
  else
    print("not correct signal")
  end
end

--shell.run("elevator")