Rednet listener

-- Listener for rednet

-- initiating variables
messages = {}
line = 1

-- monitor and rednet setup
rednet.open("back")

monitor = peripheral.wrap("top")
monitor.clear()
monitor.setTextScale(1)
monitor.setCursorPos(1, 1)

-- defining functions
function displayMsg(screen, msg, id)

    print("displaying messages")

    for i = 1, 12 do
        monitor.setCursorPos(1, i)
        monitor.setTextColor(id)
        monitor.write(msg[i])

        print("message displayed: ".. msg[i])
    end
end

function scroll(msg)

    print("scrolled")

    for i = 1, 12 do
        msg[i] = msg[i+1]
    end
    return msg
end

-- main program loop
while true do

    event, id, message = os.pullEvent()

    if event == "rednet_message" then

        print("message received")

        newMsg = tostring(id.." > "..message)
        messages[line] = newMsg

        print("message stored")

        if line < 12 then
            line = line + 1
            print("adding additional line")
        elseif line == 12 then
            messages = scroll(messages)
        else
            print("line scrolling error")
        end

        displayMsg(monitor, messages, id)

        print("text displayed")
    end
end