server

-- Open Rednet on a specific side (use "top", "bottom", "left", "right", "front", or "back")
rednet.open("top")

-- Set up the monitor on the side of the server (replace "right" with your monitor's side)
local monitor = peripheral.wrap("right")
monitor.clear()

-- Display the server's ID on the monitor
monitor.setCursorPos(1, 1)
local serverId = os.getComputerID()
monitor.write("Server ID: " .. serverId)

-- Display input prompt for server ID
monitor.setCursorPos(1, 3)
monitor.write("Enter Server ID to send file:")

-- Function to display received file info and sender's ID on the monitor
local function displayReceivedInfo(senderId, filename)
  monitor.clear()
  monitor.setCursorPos(1, 1)
  monitor.write("Server ID: " .. serverId)
  monitor.setCursorPos(1, 3)
  monitor.write("Sender ID: " .. senderId)
  monitor.setCursorPos(1, 5)
  monitor.write("Received File:")
  monitor.setCursorPos(1, 6)
  monitor.write(filename)
end

while true do
  -- Wait for user input for server ID
  local selectedServerId = tonumber(read())

  -- Listen for incoming connections from the specified server ID
  local senderId, message, protocol = rednet.receive("file_transfer")

  -- Check if the received message is a file
  if senderId == selectedServerId then
    -- Save the received file with a specific name
    local file = fs.open("received_file.txt", "w")
    file.write(message)
    file.close()
    print("File received and saved as 'received_file.txt'")

    -- Display received file info and sender's ID on the monitor
    displayReceivedInfo(senderId, "received_file.txt")
  end
end