Doggy OS network chat

-- Function to list all connected modems
local function listModems()
    local modems = {}
    for _, side in ipairs(peripheral.getNames()) do
        if peripheral.getType(side) == "modem" then
            table.insert(modems, side)
        end
    end
    return modems
end

-- Function to setup the modem
local function setupModem()
    local modems = listModems()
    if #modems == 0 then
        print("No modems found! Please connect a modem and restart.")
        return nil
    end

    print("Connected modems:")
    for i, side in ipairs(modems) do
        print(i .. ": " .. side)
    end

    -- Open the first modem found
    rednet.open(modems[1])
    print("Using modem on " .. modems[1])
    return modems[1]
end

-- Function to display a message in the chat
local function displayMessage(senderId, message, isOlderClient)
    term.setTextColor(colors.yellow) -- Set text color
    if isOlderClient then
        print("[Unknown User (" .. senderId .. ")]: " .. message) -- Show ID for older clients
    else
        print("[" .. senderId .. "]: " .. message)
    end
    term.setTextColor(colors.white) -- Reset text color
end

-- Function to handle incoming messages
local function handleIncomingMessages()
    while true do
        local senderId, message, protocol = rednet.receive()
        local username, chatMessage = message:match("^(.-): (.+)$")
        if username and chatMessage then
            displayMessage(username, chatMessage, false)
        else
            displayMessage(senderId, message, true) -- Handle messages from older clients
        end
    end
end

-- Function to send a message to all connected Rednet users
local function sendMessage(username)
    while true do
        print("Type your message (or 'exit' to quit): ")
        local userInput = read() -- Get the user's input
        if userInput == "exit" then
            print("Exiting chat...")
            shell.run("/disk/os/gui") -- Run the GUI program on exit
            break
        end
        -- Format the message to include the username
        local formattedMessage = username .. ": " .. userInput
        -- Broadcast the message to all users
        rednet.broadcast(formattedMessage)
        displayMessage(username, userInput, false)
    end
end

-- Main program
term.clear() -- Clear the terminal
term.setCursorPos(1, 1) -- Set cursor position

print("Welcome to the Doggy OS Network Chatroom!")

-- Prompt for the username
print("Enter your username:")
local username = read()

local modemSide = setupModem()
if modemSide == nil then return end -- Exit if no modem was found

print("Type 'exit' to leave the chat.")

-- Start monitoring messages in a separate thread
parallel.waitForAny(handleIncomingMessages, function()
    sendMessage(username)
end)