.menu

-- save file as .menu in root
-- most of the code from Homelab youtube tut 1
os.pullEvent = os.pullEventRaw -- prevents CTRL + T bypass
local w,h = term.getSize()
function printCentered (y,s)
    local x = math.floor((w - string.len(s)) / 2)
    term.setCursorPos(x,y)
    term.clearLine()
    term.write(s)
end
term.setTextColour(colours.orange)
local nOption = 1
local function drawMenu()
        term.clear()
        term.setCursorPos(1,1)
        term.write("Nexus OS")
        term.setCursorPos(w-8,1)
        if nOption == 1 then
            term.write("Root")
        elseif nOption == 2 then
            term.write("Programs")
        elseif nOption == 3 then
            term.write("Shutdown")
        elseif nOption == 4 then
            term.setTextColour(colours.red)
            term.write("Terminate System")
            term.setTextColour(colours.orange)
        else
            end
end

--GUI
term.clear()
local function drawFrontend()
        printCentered(math.floor(h/2) - 3, "")
        printCentered(math.floor(h/2) - 2, "Start Menu")
        printCentered(math.floor(h/2) - 1, "")
        printCentered(math.floor(h/2) + 0, ((nOption == 1) and "[ Root ]") or "Root")
        printCentered(math.floor(h/2) + 1, ((nOption == 2) and "[ Programs ]") or "Programs")
        printCentered(math.floor(h/2) + 2, ((nOption == 3) and "[ Shutdown ]") or "Shutdown")
        term.setTextColour(colours.red)
        printCentered(math.floor(h/2) + 3, ((nOption == 4) and "[ Terminate System ]") or "Terminate System")
        term.setTextColour(colours.orange)
end
--Display
drawMenu()
drawFrontend()

while true do
    local e,p = os.pullEvent()
        if e == "key" then
            local key = p
            if key == keys.up and nOption > 1 then
                nOption = nOption - 1
                drawMenu()
                drawFrontend()
            elseif key == keys.down and nOption < 4 then
                nOption = nOption + 1
                drawMenu()
                drawFrontend()
            elseif key == keys.enter then
                break
            end
        end
    end

--Conditions
if nOption == 1 then
   shell.run("os/.root")
elseif nOption == 2 then
   shell.run("os/.programs")
elseif nOption == 3 then
   os.shutdown()
elseif nOption == 4 then
   shell.run("os/terminate")
end