quarry

depth = 60
length = 7
width = 9

depthi = depth + 1
lengthi = length
widthi = width
turn_dir = "left"

turtle.refuel()
while depthi > 0 do
  depthi = depthi - 1

  while widthi > 0 do
    widthi = widthi - 1

    while lengthi > 0 do
      while turtle.getItemSpace(16) == 63 do
        os.sleep(1)
      end

      while turtle.getFuelLevel() == 1 do
        os.sleep(1)
      end

      lengthi = lengthi - 1
      turtle.dig()
      turtle.forward()
    end

    if widthi == 1 then
      turtle.digDown()
      turtle.down()
      turtle.turnRight()
      turtle.turnRight()
    elseif turn_dir == "left" then
      turtle.turnLeft()
      turtle.dig()
      turtle.forward()
      turtle.turnLeft()
      turn_dir = "right"
    elseif turn_dir == "right" then
      turtle.turnRight()
      turtle.dig()
      turtle.forward()
      turtle.turnRight()
      turn_dir = "left"
    end

    lengthi = length - 1
  end
  widthi = width
end