Menu

os.pullEvent = os.pullEventRaw

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

local nOption = 1

local function drawMenu()
    term.clear()
    term.setCursorPos(1, 1)
    term.write("Impending OS Alpha // ")
    term.setCursorPos(1, 2)
    shell.run("id")

    term.setCursorPos(w - 11, 1)
    local options = { "Command", "Programs", "Shutdown", "Uninstall" }
    term.write(options[nOption] or "")
end

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 "[ Command  ]") or "Command")
    printCentered(math.floor(h / 2) + 1, (nOption == 2 and "[ Programs ]") or "Programs")
    printCentered(math.floor(h / 2) + 2, (nOption == 3 and "[ Shutdown ]") or "Shutdown")
    printCentered(math.floor(h / 2) + 3, (nOption == 4 and "[ Uninstall ]") or "Uninstall")
    printCentered(math.floor(h / 2) + 4, "")
end

-- Display
drawMenu()
drawFrontend()

while true do
    local event, key = os.pullEvent("key")

    if key == keys.z or key == keys.up then -- "Z" instead of "W" for QWERTZ
        if nOption > 1 then
            nOption = nOption - 1
            drawMenu()
            drawFrontend()
        end
    elseif key == keys.s or key == keys.down then
        if nOption < 4 then
            nOption = nOption + 1
            drawMenu()
            drawFrontend()
        end
    elseif key == keys.enter then
        break
    end
end

term.clear()

-- Conditions for selection
if nOption == 1 then
    shell.run("ios/.command")
elseif nOption == 2 then
    shell.run("ios/.programs")
elseif nOption == 3 then
    os.shutdown()
elseif nOption == 4 then
    shell.run("ios/.UninstallDialog")
end