function refuel()
  if turtle.getFuelLevel() < 1000 then
    turtle.select(2)
    turtle.refuel(10)
  end
end

function torch()
  turtle.turnLeft()
  turtle.turnLeft()
  turtle.select(1)
  if turtle.getItemCount(1) > 1 then turtle.place() end
  turtle.turnLeft()
  turtle.turnLeft()
end

function tunnel(l)
local light = 0
for i=1, l do
  refuel()
  while turtle.detect() do turtle.dig() end
  turtle.forward()
  if i == 1 then torch() end
  light = (light + 1)
  if light >= 13 then torch() light = 0 end
  while turtle.detectUp() do turtle.digUp() end
  turtle.select(3)
  turtle.placeDown()

end
end

function turn(direction)
  if direction then turtle.turnLeft() end
  if not direction then turtle.turnRight() end
  tunnel(4)
  if direction then turtle.turnLeft() end
  if not direction then turtle.turnRight() end
end




function restock()
	turtle.dig()
	turtle.select(4)
	turtle.place()
	turtle.select(5)
	turtle.placeUp()
	for i=5, 16 do turtle.select(i) turtle.drop() end
	turtle.select(1)
	turtle.suckUp(turtle.getItemSpace(1))
	turtle.select(4)
	turtle.dig()
	turtle.select(5)
	turtle.digUp()
	turtle.select(1)
	turtle.place()
end

args = {...}
local length = args[1]
if length == nil then print("Error Invalid Argument. ex: Dig (length) [left:right] [width] [r]") error() end
local d = args[2]
  local direct = false
  if d == "left" then direct = true end
local rows = args[3]
if rows == nil then rows = 1 end
local dump = args[4]

print(" Please add:")
print("torches to Slot 1")
print("fuel to slot 2")
print("cobble to slot 3")
if dump == "r" then print("Drop off chest to slot 4 and optionally a chest of torches to slot 5") end
print("Press enter to continue.")
read("*")
term.clear()
term.setCursorPos(1,1)

while true do

	for i=1, rows do
		tunnel(length)
		turn(direct)
		direct = not direct
		tunnel(length)
		if dump == "r" then restock() end
		turn(direct)
		direct = not direct
	end

	print("Press enter to continue.")
	read("*")
	term.clear()
	term.setCursorPos(1,1)
end