fuel

local fuel = 0

function setFuelLevel(min)
  fuel = min
end
function getMinFuel()
  return fuel
end

function isFull()
  for i = 1,16 do
    if turtle.getItemCount(i) == 0 then
      return false
    end
  end
  return true
end


function refuel()
  local f = turtle.getFuelLevel()

  if f < fuel then
    local count = 1
    turtle.select(count)

    repeat
      f = turtle.getFuelLevel()

      if not turtle.refuel(1) then
        count = count + 1
        if count > 16 then return -1 end
        turtle.select(count)
        --turtle.select(
        --(turtle.getSelectedSlot() < 16 and turtle.getSelectedSlot()+1)
        --or 1)
      end

    until f >= fuel
    return 1 -- fueling success
  end

  return 0 --no need to refuel
end

function ret() --stands for return,
               --as in return to base
  if isFull() or refuel() == -1 then
    return true
  end
  return false
end


function idle()
  if isFull() then
    print("Inventory is full, press q to end")
    local t = read()
    if t == "q" or t == "Q" then return -1 end
    idle()
  end
  if refuel() == - 1 then
    print("Need more fuel")
    print(turtle.getFuelLevel())
    print("Press q to end")
    local t = read()
    if t == "q" or t == "Q" then return -1 end
    idle()
  end
  return 1
end