ComputerCraft: 'stairs' Digs stairs up or down

--v2.1 by GraySloth 2013-Feb-23
--here is an old video demonstration of my scripts, it is almost good. http://youtu.be/9vhl7dSENs8
local tArgs = { ... }
if #tArgs ~= 2 then
    print( "Usage: stairs [up|down] <#height>" )
    return
end


local size = tonumber( tArgs[2] )
if size < 1 then
    print( "stairs height must be positive" )
    return
end

--functions
function fuelCheck()
    if turtle.getFuelLevel() == "unlimited" then
    return true
    elseif turtle.getFuelLevel() < 2 then
      print("Traveled "..dist.." of "..tArgs[2]..", Need more fuel")
      print("Searching for fuel hold ctrl+t to stop")
      while turtle.getFuelLevel() < 10 do
         for n=1,16 do
            if turtle.getFuelLevel() < 10 then
               turtle.select(n)
               turtle.refuel(1)
            end
         end
      end
      print("Refueled: "..turtle.getFuelLevel())
   end
end

local dist = 0
function count()
dist = dist + 1
   if (math.fmod( dist, 8 ) == 0) or (math.fmod( dist, tArgs[2] ) == 0) then
      print("Traveled "..dist.." of "..tArgs[2]..", Fuel: "..turtle.getFuelLevel())
   end
end
--Main
local stop = 0
print("Fuel level: "..turtle.getFuelLevel())
if (tArgs[1] == ("down")) or (tArgs[1] == ("dn")) then
   for i = 1, size do
      fuelCheck()
      if turtle.digDown() then
            stop = 0
         else
            stop = stop + 1
         end
      turtle.down()
      turtle.dig()
          while not turtle.forward() do
            turtle.dig()
          end
      turtle.digUp()
      count()
      if stop == 4 then
            print("Traveled "..dist.." of "..tArgs[2]..", Fuel: "..turtle.getFuelLevel())
            print("stopped")
            return
         end
    end
elseif tArgs[1] == ("up") then
      for i = 1, size do
         fuelCheck()
         turtle.dig()
          while not turtle.forward() do
            turtle.dig()
          end
         if turtle.digUp() then
            stop = 0
         else
            stop = stop + 1
         end
         turtle.up()
         turtle.digUp()
         count()
         if stop == 4 then
            print("Traveled "..dist.." of "..tArgs[2]..", Fuel: "..turtle.getFuelLevel())
            print("stopped")
            return
         end
       end
else
   print( "Usage: stairs <up|down> <height>" )
   return
end
print("Done")