local function clock_display(sec)
	local s = math.floor(sec) % 60
	local m = math.floor(sec / 60) % 60

	if sec > 3599 then
		local h = math.floor(sec / 3600)
		return string.format('%d:%02d:%02d', h, m, s)
	else
		return string.format('%d:%02d', m, s)
	end
end

if settings.startup['PHI-XC'].value then
    script.on_nth_tick(60, function(event)
        for _, player in pairs(game.connected_players) do
            if player.gui.top.phi_clock == nil then
                player.gui.top.add{type='button', name='phi_clock'}
            end

            player.gui.top.phi_clock.caption = clock_display(math.floor(event.tick / 60))
        end
    end)
end