startup

--mana
local target = 12
--comparator
local compSide = "front"
---cakeChest
local chestSide = "back"
local reverse = "south"
--turtle
local buffer = 16
local cakeSlot = 1

local chest = peripheral.wrap(chestSide)

function lowCake()
  return turtle.getItemCount(cakeSlot) < (buffer/2)
end

function round(n)
  return n % 1 >= 0.5 and math.ceil(n) or math.floor(n)
end

function refillCake()
  if lowCake() then
    local as = chest.getAllStacks()
    for i=1,#as do
      if as[i].name == "cake" and lowCake() then
        chest.pushItem(reverse,i,(buffer-turtle.getItemCount(cakeSlot)),cakeSlot)
      end
    end
  end
end

function getLevel()
  local lvl = rs.getAnalogInput(compSide)
  print("Mana level is "..round(lvl*100/15).."%")
  return lvl
end

refillCake()
while true do
  while getLevel() < target do
    print("RECHARGING!")
    if not turtle.detectUp() then
      turtle.select(cakeSlot)
      if turtle.placeUp() then
        refillCake()
      else
        print("Error placing cake!")
      end
    else
      print("Previous cake still present!")
    end
    sleep(8)
  end
  sleep(8)
end