local auto_refill = false  -- set to false if you dont want get refilled your stack automatic

function refill(player, stck_name, index)
	local inv = player:get_inventory()
	for i,stack in ipairs(inv:get_list("main")) do
		if stack:get_name() == stck_name then
			inv:set_stack("main", index, stack)
			stack:clear()
			inv:set_stack("main", i, stack)
			minetest.log("action", "intweak-mod: refilled stack of"  .. player:get_player_name()  )
			return
		end
	end
end

if auto_refill == true then
	minetest.register_on_placenode(function(pos, newnode, placer, oldnode)
		if not placer then return end
		local index = placer:get_wield_index()
		local cnt = placer:get_wielded_item():get_count()-1
		if cnt == 0 then minetest.after(0.01, refill, placer, newnode.name, index) end
	end)
end