netherTunnel

args={...}
local iterations=tonumber(args[1])
if #args==0 then
  repeat
    io.write("Distance: ")
    iterations=tonumber(io.read())
    print("")
  until iterations~=nil and iterations>0
end

local function refill()
  if turtle.getItemCount(1)==0 then
    for i=2,16 do
      if turtle.getItemCount(i)~=0 then
        turtle.select(i)
        turtle.transferTo(1)
        turtle.select(1)
      end
    end
  end
end

oldTurtle={}
oldTurtle.place=turtle.place
oldTurtle.placeUp=turtle.placeUp
oldTurtle.placeDown=turtle.placeDown
oldTurtle.dig=turtle.dig
oldTurtle.digUp=turtle.digUp
oldTurtle.digDown=turtle.digDown
turtle.place=function()
  refill()
  while not oldTurtle.place() and not turtle.detect() do
      turtle.attack()
  end
end
turtle.placeUp=function()
  refill()
  while not oldTurtle.placeUp() and not turtle.detectUp() do
    turtle.attackUp()
  end
end
turtle.placeDown=function()
  refill()
  while not oldTurtle.placeDown() and not turtle.detectDown() do
    turtle.attackDown()
  end
end
turtle.dig=function()
  while turtle.detect() and not oldTurtle.dig() do
    turtle.attack()
  end
end
turtle.digUp=function()
  while turtle.detectUp() and not oldTurtle.digUp() do
    turtle.attackUp()
  end
end
turtle.digDown=function()
  while turtle.detectDown() and not oldTurtle.digDown() do
    turtle.attackDown()
  end
end
for i=1,iterations do
  turtle.digDown()
  turtle.placeDown()
  turtle.digUp()
  turtle.turnLeft()
  turtle.dig()
  turtle.place()
  turtle.up()
  turtle.dig()
  turtle.place()
  turtle.turnRight()
  turtle.digUp()
  turtle.placeUp()
  turtle.turnRight()
  turtle.dig()
  turtle.place()
  turtle.down()
  turtle.dig()
  turtle.place()
  turtle.turnLeft()
end