Turtlescript Stairs Command

--[[
7/1/2014 Created Stairs
Logic borrowed from http://turtlescripts.com/project/gjdh4w-Staircases
- by johncena1469
Inspiration: everyone who has built turtle staircases
--]]

function pauseAnyKey()
   -- if event == "key" and p1 == keys.q then
   while true do
        local event, p1,p2,p3 = os.pullEvent()
        if event == "key" then
            return p1
        end
        sleep(0.5)
   end
end

function refuel()
    --Check fuel and refuel if nessesary
    --Code source: sethbling http://www.youtube.com/watch?v=DSsx4VSe-Uk&feature=share&list=SP2Qvl4gaBge02Eh4AqtDSWg3sojt3jeRO

    while turtle.getFuelLevel() < 200 do
        turtle.select(16)
        if turtle.getItemCount() < 1 then
            print("Turtle is out of fuel, please add fuel to slot 16")
            print("then press any key to continue")
            pauseAnyKey()
        end
        turtle.refuel(1)
    end
end

function nextInventory()
   for i=1,15 do
       turtle.select(i)
       if turtle.getItemCount() > 0 then
           return i
       end
    end

    return false
end

function getInventory()
      slot = nextInventory()
      if slot == false then
          print("Out of inventory")
          print("Please reload inventory")
          print("Then press any key")
          pauseAnyKey()
          slot = nextInventory()
          if slot == false then
              print("Looks like you've given up!")
              return
          end
      end
      turtle.select(slot)
end

function digFront()
      while turtle.detect() do
          turtle.dig()
          turtle.attack()
      end
end

function digUp()
      while turtle.detectUp() do
          turtle.digUp()
          turtle.attackUp()
      end
end

function digDown()
    while turtle.detectDown() do
        turtle.digDown()
        turtle.attackDown()
    end
end

function putDown()
    if not turtle.detectDown() then
        turtle.placeDown()
    end
end

function buildDown(height)
    refuel()

    for i=1, height do
        digFront()
    	turtle.forward()
    	digUp()
    	digDown()
    	turtle.up()
    	digUp()
    	turtle.down()
    	turtle.down()
    	getInventory()
    	putDown()
    end
    for i=1, height do
        digUp()
    	turtle.up()
    	turtle.back()
    	getInventory()
        putDown()
    end
end

function buildUp(height)
    refuel()

    for i=1, height do
        digFront()
        digUp()
        getInventory()
        turtle.up()
        turtle.forward()
        putDown()
    end

    for i=1, height do
        turtle.back()
        digDown()
        turtle.down()
        getInventory()
        putDown()
    end

end

args = { ... }

if #args ~= 2 then
    print("Usage:")
    print("")
    print("  stairs <up|down> <height>")
    return
end

test = string.sub( args[1], 1, 1)
test = string.lower( test )

if string.find("du",test) == nil then
    print("Direction must be one of 'up' or 'down'")
    return
end

direction = test

h = tonumber(args[2])

if h == nil or h < 0 then
    print("Height must be a real number higher than 0")
    return
end

if refuel == false then
    print("The turtle needs fuel, please put fuel in slot 16")
    return
end

if direction == "u" then
    buildUp(h)
else
    buildDown(h)
end