ComputerCraft turtle program - Enchanting

local xpApi = peripheral.wrap("right")
local collectedXp

while 1 do
    if redstone.getInput("top") == true then
        collectedXp = xpApi.collect()
        if collectedXp > 0 then
            print("Collected " .. collectedXp .. " XP. Current level is " .. xpApi.getLevels())
        end
        if xpApi.getLevels() >= 30 then
            for i = 1, 15, 1 do
                if turtle.getItemCount(i) > 0 then
                    turtle.select(i)
                    break
                elseif i == 15 then
                    print("out of books!")
                end
            end
            turtle.transferTo(16, 1)
            turtle.select(16)
            xpApi.enchant(30)
            turtle.drop()
            print("Book enchanted..")
        end
        sleep(5)
    else
        sleep(10)
    end
end