Strip Mine

local length = 0

print("How long do you want the tunnel?")
length = io.read()
length = tonumber(length)

for i=0, length do
	if (turtle.detect() and i < length) then
		turtle.dig()
	end
	if turtle.detectUp() then
		turtle.digUp()
	end
	if turtle.detectDown() then
		turtle.digDown()
	end
	if (i%10==0) then
		turtle.select(2)
		turtle.placeDown()
		turtle.select(1)
	end
	if (turtle.detect() == false) then
		turtle.forward()
	end
	if (turtle.getFuelLevel() <= 1) then
		turtle.refuel(1)
	end
end

turtle.turnLeft()
turtle.turnLeft()

for i=0, length-1 do
	if turtle.detect() then
		turtle.dig()
	end
	turtle.forward()
	sleep(1)
end