GokOS

--Menu System
local WIDTH, HEIGHT = term.getSize()
local menuItems = {

    {
        "OS Update",
        function()
            term.clear()
            term.setCursorPos(1,1)
            term.write("Updating...")
            os.sleep(1)
            if fs.exists("startup") then
                shell.run("delete startup")
            end
            shell.run("pastebin get vpMfYK0v startup")
            os.reboot()
        end
    },

    {
        "Programs",
        function()
            term.clear()
            term.setCursorPos(1,1)
            term.write("No functionality yet!")
            os.sleep(1)
            return
        end
    },

    {
        "Install",
        function()
            term.clear()
            term.setCursorPos(1,1)
            term.write("Soon to be way of installing ur fav programs")
            os.sleep(1)
        end
    },

    {
        "Quit",
        function()
            term.clear()
            term.setCursorPos(1,1)
            term.write("Shutting down...")
            os.sleep(1)
            return true
        end
    }

}

function runSelection(option)
    return menuItems[option][2]()
end

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

    --Check if installation is proper etc..
end

--Prints text in the center of a selected row
function printCenter(h, msg)
    term.setCursorPos(math.floor((WIDTH-string.len(msg))/2), h)
    term.clearLine()
    term.write(msg)
end

function drawMenu(option)
    term.clear()
    for i, item in ipairs(menuItems) do
        if i == option then
            term.setTextColor(colors.lightBlue)
            printCenter(i+3, "["..item[1].."]")
            term.setTextColor(colors.white)
        else
            printCenter(i+3, item[1])
        end
    end
end

--TODO: Add a function for checking on updates (FOR NOW JUST GETS STARTUP)


initScreen()
local option = 1

while true do

    drawMenu(option)

    local event, key = os.pullEvent("key")

    if key == keys.up then
        option = option - 1
    elseif key == keys.down then
        option = option + 1
    end

    --Bound check options
    if option > table.getn(menuItems) then
        option = option - 1
    elseif option == 0 then
        option = option + 1
    end

    drawMenu(option)

    if key == keys.enter then
        if runSelection(option) == true then
            term.clear()
            term.setCursorPos(1,1)
            break
        end
    end
end