Turtle XyCraft Multitank Builder

--[[
  (C) LayZee 2013
  Xycraft MultiTank Builder

  Indtil videre kan den grave ud ved at skrive
    lzXyTank down
  hvis den starter i oeverste lag eller
    lzXyTank up
  hvis den starter i nederste lag
--]]

local argument = {...}
local validArgument
local directionMove
local directionDig

function initialize ()
  direction = tostring(argument[1])

  if direction == "down" then
    directionMove = turtle.down
    directionDig = turtle.digDown

    return true
  elseif direction == "up" then
    directionMove = turtle.up
    directionDig = turtle.digUp

    return true
  else
    print("Usage: lzXyTank <up|down>")

    return false
  end
end


function digMove ()
  turtle.dig()

  while not turtle.forward() do
    turtle.dig()
    sleep(0.8)
  end
end

function digRow ()
  for block = 1, 13 do
    digMove()
  end
end

function digLayer (layer)
  if layer % 2 == 1 then
    oddTurn = turtle.turnRight
    evenTurn = turtle.turnLeft
  else
    oddTurn = turtle.turnLeft
    evenTurn = turtle.turnRight
  end

  for row = 1, 14 do
    digRow()

    if row < 14 then
      if row % 2 == 1 then
        oddTurn()
        digMove()
        oddTurn()
      else
        evenTurn()
        digMove()
        evenTurn()
      end
    end
  end
end

function digSpace ()
  for layer = 1, 14 do
    digLayer(layer % 2)
    turtle.turnLeft()
    turtle.turnLeft()

    if layer < 14 then
      directionDig()

      while not directionMove() do
        directionDig()
        sleep(0.8)
      end
    end
  end
end

--Main program
if initialize() then
  digSpace()
else
  print("Terminating lzXyTank")
end