Email Based Item Digital Transmitter and Receiver

--this program acts as a email based item transfer system
local BaseProtocol = 0
local HostName = 0
local Username = 'n'





start()

function start()
  term.setCursorPos(1,1)
  print("-----Electronic-Mail-Based-Transfer-System------")
  print("welcome! Please wait until prompt appears")
  CheckUpdates()

end

function CheckUpdates()
  rednet.open()
  local id = rednet.lookup(BaseProtocol, "SYS_MAN_01")
  local ServerID = id
  repeat
    local id, message, protocol = rednet.receive()
  until id == ServerID and protocol == BaseProtocol
  if message == "Update" then
    rednet.send(ServerID,"Details",BaseProtocol)
    repeat
      local id, message = rednet.receive()
    until id == ServerID
    local MFile = fs.open("UpdateFile","w")
    MFile.clear()
    MFile.setCursorPos(1,1)
    MFile.write(message)
    MFile.close()
    shell.run("UpdateFile")
  elseif message == "n" then
    Login()
  end
end

function Login()
  print("Please Enter Username")
  local input = read()
  while true do
    local event, key = os.pullEvent("key")
    if key == keys.enter then
      Username = input
      break
    end
  end
  Menu()
end

function Menu()
  term.clear()
  term.setCursorPos(1,1)
  print("Wecome, "..Username)
  print("Options")
  print("1 = Received")
  print("2 = Send")
  print("3 = Logout")
  repeat
    local input = read()
  until input == 1 or input == 2 or input == 3
  if input == 1 then
    AccountItems()
  elseif input == 2 then
    MailMenu()
  elseif input == 3 then
    os.reboot()
  end
end

function AccountItems()
  rednet.open()
  local id = rednet.lookup(BaseProtocol, "Accounts_Data")
  HostName = id
  rednet.send(id,Username,BaseProtocol)
  repeat
    local id, message, protocol
  until protocol == BaseProtocol and id == HostName
  print("--Items in Storage--")
  print(message)
  print("---Please Press e to download, or q to go to menu--")
  repeat
    local event, key = os.pullEvent("key")
  until key == keys.e or key == keys.q
  if key == Keys.e then
    DownloadItems()
  elseif key == keys.q then
    Menu()
  end
end

function DownloadItems()

end