file_sender

local port = 12345
local component = require('component')
local modem = component.modem
local ser = require('serialization')
local endfile = '|||END FILE|||'

local function writeFile(modem_type, filename)
  local event = require('event')
  if modem_type == 'modem' then
    modem.open(port)
  end

  while true do
    local event, receiver, sender, port, distance, message = event.pull()

    if event == 'modem_message' then
      if not filename then
        filename = ser.unserialize(message)[1]
      end
      str = ser.unserialize(message)[2]

      if str == endfile then
        break
      else
      print(filename)
        local file = io.open(filename, 'a')
        file:write(str)
        file:close()
      end
    end
  end

  if modem_type == 'modem' then
    modem.close(port)
  end

  print('File: '..filename..' received')
end

local function sendFile(modem_type, filename)
  file = io.open(filename, 'r')
  if not file then
    print('Error: File not exist')
  os.exit()
  else
    sFile = file:read('*a')
    if modem_type == 'modem' then
      if #sFile > modem.maxPacketSize()+#filename then
        for i = 1, ( math.floor(#sFile) / ( (modem.maxPacketSize() - #filename) - 16 ) ) do
          modem.broadcast(port, ser.serialize({filename, string.sub(sFile, i, i+modem.maxPacketSize)}))
        end
        modem.broadcast(port, ser.serialize({filename, endfile}))
      else
        modem.broadcast(port, ser.serialize({filename, sFile}))
        os.sleep(0.1)
        modem.broadcast(port, ser.serialize({filename, endfile}))
      end
    elseif modem_type == 'tunnel' then
      local tunnel = component.tunnel
      if #sFile > tunnel.maxPacketSize()+#filename then
        for i = 1, ( math.floor(#sFile) / ( (tunnel.maxPacketSize() - #filename) - 16 ) ) do
          tunnel.send(ser.serialize({filename, string.sub(sFile, i, i+tunnel.maxPacketSize)}))
        end
        tunnel.send(ser.serialize({filename, endfile}))
      else
        tunnel.send(ser.serialize({filename, sFile}))
        os.sleep(0.1)
        tunnel.send(ser.serialize({filename, endfile}))
      end
    end
  end
  file:close()
  print('File: '..filename..' sended')
end

local function checkType()
  print('Enter type of modem (modem/tunnel): ')
  return io.read()
end

tArgs = {...}

if tArgs[1] == 'send' then
  sendFile(checkType(), tArgs[2])
elseif tArgs[1] == 'receive' then
  writeFile(checkType())
elseif #tArgs == 3 then
  writeFile(checkType(), tArgs[3])
elseif #tArgs > 3 or #tArgs == 0 then
  print('Usage:\nfile_sender <send> <filename>\nfile_sender <receive>')
end