rasen

STAIR = 1
SLAB = 2
FUEL = 16

N = 3

function wait_for_enough_fuel(minLevel, slot)
  local qty = 0
  local refuel = function()
    turtle.select(slot)
    turtle.refuel()
    qty = turtle.getFuelLevel()
    print("fuel: ",qty)
    return qty
  end

  while refuel() < minLevel do
    print(string.format("Insert fuel-items into slot %d: %d/%d", slot, qty, minLevel))
    os.sleep(1)
    os.pullEvent("turtle_inventory")
  end
end

function set_block(slot, direction)
  turtle.select(slot)
  if direction==nil then
  turtle.place()
  elseif direction=="bottom" then
    turtle.placeDown()
  elseif direction=="top" then
    turtle.placeUp()
  end
end

function slide(direction, n)
  if direction == "left" then
    turtle.turnLeft()
    turtle.forward()
    turtle.turnRight()
  elseif direction=="right" then
    turtle.turnRight()
    turtle.forward()
    turtle.turnLeft()
  end
end

function stair3()
    turtle.forward()
    if not turtle.detectDown() then set_block(SLAB, "bottom") end
    turtle.back()
    set_block(STAIR)
    slide("left")
    turtle.forward()
    if not turtle.detectDown() then set_block(SLAB, "bottom") end
    turtle.back()
    set_block(STAIR)
    slide("left")
    turtle.forward()
    if not turtle.detectDown() then set_block(SLAB, "bottom") end
    turtle.back()
    set_block(STAIR)
end
-- main
local args = {...}
if args and args[1] then N = tonumber(args[1]) end

wait_for_enough_fuel(100, FUEL)

for i=1,N do
stair3()
turtle.up()
turtle.forward()
turtle.forward()
set_block(SLAB, "bottom")
set_block(SLAB, "bottom")
slide("right")
set_block(SLAB)
turtle.turnRight()
turtle.forward()
set_block(SLAB,"bottom")
set_block(SLAB,"bottom")
turtle.back()
set_block(STAIR)
turtle.turnLeft()
set_block(SLAB,"bottom")
set_block(SLAB,"bottom")
turtle.back()
slide("right")
turtle.up()
turtle.forward()
turtle.forward()
turtle.turnRight()
set_block(SLAB, "bottom")
slide("left")
set_block(SLAB, "bottom")
slide("right")
slide("right")
end

--[[
while true do
local text = read()
if text == "exit()" then break end
local func = loadstring(text)
setfenv(func, getfenv()) -- change func's environment(_G) to current one.
local results = {pcall(func)} -- table: 1) exist_status, 2) run_status, 3) err_msg
end
--]]