Turtle Pure Crystal Harvest

local crystalSlot = 16
local fullSlots = 0

-- Functions
local function wait()
    os.sleep(290)
end

local function getItems()
    for i = 1, 15 - fullSlots do
        turtle.select(i)
        turtle.suck()
    end
end

local function transferCrystals(amount)
    -- crystalSlot has Crystals or is empty
    local currentSlot = turtle.getSelectedSlot()
    if (turtle.getItemDetail(crystalSlot) == nil or turtle.getItemDetail(crystalSlot).name == "appliedenergistics2:item.ItemMultiMaterial") then
        print("Slot clear.")
    else
        print("Crystal Slot is used. Dropping items...")
        turtle.select(crystalSlot)
        drop()
        turtle.select(currentSlot)
        print("Items dropped.")
    end
    turtle.transferTo(crystalSlot, amount)
end

local function moveCrystalSlot()
    fullSlots = fullSlots + 1
    crystalSlot = crystalSlot - 1
end

local function compareSlots()
    local haveSeeds = false
    for i = 1, 15 - fullSlots do
        turtle.select(i)
        if (turtle.getItemDetail() and turtle.getItemDetail().name == "appliedenergistics2:item.ItemMultiMaterial") then
            print("Finished some Crystals.")
            if (turtle.getItemSpace(crystalSlot) == 0) then
                moveCrystalSlot()
                turtle.transferCrystals(turtle.getItemCount())
            elseif (turtle.getItemCount() > turtle.getItemSpace(crystalSlot)) then
                transferCrystals(turtle.getItemSpace())
                moveCrystalSlot()
                transferCrystals(turtle.getItemCount())
            else
                transferCrystals(turtle.getItemCount())
            end
        elseif (turtle.getItemDetail() and turtle.getItemDetail().name == "appliedenergistics2:item.ItemCrystalSeed") then
            turtle.drop()
            print("Still have seeds.")
            haveSeeds = true
        else
            turtle.drop()
        end
    end

    if (haveSeeds == true) then
        print("Restart process...")
        return false
    end

    return true
end

while(compareSlots() == false) do
    wait()
    getItems()
end