Computer Craft chat with monitor

-- Get the username and channel
write("Username: ")
username = read()
write("Channel: ")
channel = read()

term.clear()
term.setCursorPos(1,1)

-- Open any modems on the computer
peripheral.find("modem", rednet.open)
message = ""

-- Find and set up monitor
local monitor = peripheral.find("monitor")
if monitor then
    monitor.setTextScale(1) -- adjust for readability
    monitor.clear()
    monitor.setCursorPos(1, 1)
else
    print("No monitor found, running in terminal only.")
end

-- Keep track of where we are printing on the monitor
local monX, monY = 1, 1
local function monPrint(text)
    if monitor then
        monitor.setCursorPos(monX, monY)
        monitor.write(text)
        monY = monY + 1
        if monY > select(2, monitor.getSize()) then
            monitor.scroll(1)
            monY = select(2, monitor.getSize())
        end
    end
end

-- Receives chat messages from other clients on the same channel
function receiveChat()
    while true do
        local id, msg, chan = rednet.receive(channel)
        if msg then
            print(msg)
            monPrint(msg)
        end
    end
end

-- Sends messages to other clients on the same channel
function sendMsg()
    while true do
        write(">: ")
        message = read()
        if message == "exit[]" then
            os.reboot()
        end
        term.clearLine()
        local fullMsg = username .. ": " .. message
        rednet.broadcast(fullMsg, channel)
        monPrint(fullMsg)
    end
end

-- Runs the functions in parallel so you can receive and send messages at the same time
parallel.waitForAny(receiveChat, sendMsg)