serum refiller

local args = {...}

local serumSlot = 2

function dumpSerum()
  while turtle.getItemCount(1) > 0 do
    turtle.select(1)
    while not turtle.drop() do
      print("failed to drop serum")
      sleep(1)
    end
  end
end

function synthesizerDone()
  local mach = peripheral.wrap("bottom")
  local itemInfo = mach.getStackInSlot(serumSlot)

  return itemInfo ~= nil and itemInfo["dmg"] == 0
end

function purifierDone()
  local mach = peripheral.wrap("bottom")
  local itemInfo = mach.getStackInSlot(serumSlot)

  -- shouldn't happen
  if itemInfo == nil then
    return false
  end

  -- Since there's nothing better to go by, we're
  --  going to guess if it's done based on how
  --  how it's energy storage changes over the course
  --  of a few seconds.

  -- If we're low on BNA, assume we're waiting for more
  local bnaTank = mach.getTanks("unknown")[1]
  if (bnaTank.amount == nil or bnaTank.amount < 1000) then
    return false
  end

  local maxPow = 0 + mach.getMaxEnergyStored()
  local startPow = 0 + mach.getEnergyStored()
  sleep(2)
  local endPow = 0 + mach.getEnergyStored()

  -- if the machine is almost full, assume we're done
  if (maxPow - endPow) < 10 then
    return true
  end

  -- I'm afraid of odd ball behavior when we're almost
  --   out of power, let's play it safe
  if endPow < 1000 then
    return false
  end

  -- if we had a gain in energy, we're done
  if endPow - startPow > 20 then
    return true
  end

  -- Either there is an energy shortage, or we're still
  --  working
  return false
end

local machineDone = nil
if args[1] == "purifier" then
  machineDone = purifierDone
elseif args[1] == "synthesizer" then
  machineDone = synthesizerDone
else
  print("bad machine name, or arg")
  print("expected one of: purifier, synthesizer")
  error()
end

function machineEmpty()
  local mach = peripheral.wrap("bottom")
  local itemInfo = mach.getStackInSlot(serumSlot)

  return itemInfo == nil
end

function transferSerum()
  turtle.select(1)
  turtle.suckDown()
end

function main()
  dumpSerum()
  while true do
    if machineEmpty() then
      sleep(15)
    else
      if machineDone() then
        transferSerum()
        dumpSerum()
      else
        sleep(1)
      end
    end
  end
end

main()