os.loadAPI("file")

dists = 1
is = 1
js = 1

fwd = function()
  refuel()

  while turtle.detectUp()==true do
    turtle.digUp()
  end

  turtle.digDown()

  while turtle.forward()==false do
    turtle.dig()
  end
end

refuel = function()
  if turtle.getFuelLevel()<20 then
    if turtle.getItemCount(16)==1 then
      print("out of fuel!")
      exit()
    end

    turtle.select(16)

    if turtle.refuel(1)==false then
      print("problem fueling!")
      exit()
    end

    turtle.select(15)
  end

  if isfull() then
    empty()
  end
end

isfull = function()
  local full = true

  for i=1,14 do
    if turtle.getItemCount(i)==0 then
      full = false
    end
  end

  return full
end

empty = function()
  turtle.digDown()
  turtle.select(15)
  turtle.placeDown()
  for i=1,14 do
    turtle.select(i)
    turtle.dropDown()
  end
  turtle.select(15)
  turtle.digDown()
end

write = function(dist, i, j)
  file.write("state", {dist, i, j})
end

spiral = function()
  dist = dists

  turtle.select(15)
  turtle.digDown()

  while true do
    dist = dist + 1

    for i=is,2 do
      for j=js,dist do
        fwd()
        write(dist-1, i, j+1)
      end
      js = 1
      turtle.turnRight()
      write(dist-1, i+1, 1)
    end
    is = 1
  end
end

start = function(dist, i, j)
  dists = dist
  is = i
  js = j
end