startup

function compactInv()
  for i = 1,16 do
    if turtle.getItemCount(i) > 0 and turtle.getItemCount(i) < 64 then
      turtle.select(i)
      for j = i+1,16 do
        if turtle.compareTo(j) then
          turtle.select(j)
          turtle.transferTo(i)
          turtle.select(i)
        end
      end
    end
  end

  for i = 1,16 do
    if turtle.getItemCount(i) > 0 then
      for j = 1,i do
        if turtle.getItemCount(j) == 0 then
          turtle.select(i)
          turtle.transferTo(j)
          break
        end
      end
    end
  end
end

function nextSlot(slot)
  if slot == 16 then
    return 1
  else
    return slot + 1
  end
end

function sendStackToPackager(packager,slot,packetSize)
  print("Sending slot "..slot.. " to packager in packets of "..packetSize.." items.")
  waitBeforeNextSlot = not turtle.compareTo(nextSlot(slot))

  while turtle.getItemCount(slot) > 8 do
    --print("  enough items left to package ("..turtle.getItemCount(slot)..").")
    buffer = packager.getStackInSlot(1)
    while buffer ~= null and buffer["qty"] > 54 do
      print("--Packager Overflow : Waiting 3s ("..buffer["qty"].." items left).")
      sleep(3)
      buffer = packager.getStackInSlot(1)
    end
    print("--Packager OK : dropping down "..packetSize.." items from slot "..slot..".")
    turtle.dropDown(packetSize)
    sleep(0.2)
  end

  if waitBeforeNextSlot then
    buffer = packager.getStackInSlot(1)
    while buffer ~= null and buffer["qty"] > 0 do
      if bak == buffer["qty"] then
        print("There seems to be a problem with the packager : buffer size("..bak..") doesn't change.")
      end
      bak = buffer["qty"]

      print("--Slot Transiton : waiting ...")
      sleep(1.2)

      buffer = packager.getStackInSlot(1)
    end
  end
end


local packager = peripheral.wrap("bottom")
while true do
  print("Compacting ...")
  compactInv()
  for i=1,16 do
    turtle.select(i)
    sendStackToPackager(packager,i,9)
    sleep(0.2)
  end
  sleep(2)
end