walls3

version = "walls3: Rev 0.1"
mission= "Place 3-block high walls at the length and width specified."
instructions = "Place stack(s) of material starting in first slot."

args = {...}
nArgs = #args

usage = "walls3 <length> <width>"

materialSlot = 1

if nArgs == 0 or (nArgs == 1 and args[1]== "help") then
	print(version)
	print(mission)
	print(instructions)
	print(usage)
	return
end

if nArgs ~= 2 then
  print(usage)
  return
end

length = tonumber(args[1])
if length == nil then
  print("\"", args[1], "\" is not a valid length")
  return
end
if length < 1 then
  print("length must be a positive number greater than zero")
end

width = tonumber(args[2])
if width == nil then
  print("\"", args[2], "\" is not a valid width")
  return
end
if width < 1 then
  print("width must be a positive number greater than zero")
end

function place()
	ensureMaterial()
	turtle.place()
end

function placeUp()
	ensureMaterial()
	turtle.placeUp()
end

function placeDown()
	ensureMaterial()
	turtle.placeDown()
end

function ensureMaterial()
	if turtle.getItemCount(materialSlot) < 3 then
		organizeMaterial()
	end
	if turtle.getItemCount(materialSlot) < 3 then
		print("No more material")
		return false
	end
	return true
end

function organizeMaterial()
	local i
	materialCount = turtle.getItemCount(materialSlot)

	if materialCount < 6 then
--		print("Attempting to refill slot ", materialSlot)
		for i=2,12 do
			turtle.select(i)
			if turtle.compareTo(materialSlot) then
				turtle.transferTo(materialSlot)
			end
		end
	end
	turtle.select(materialSlot)
end

function buildWall(length)
	for i=1,length do
		ensureMaterial()
		turtle.select(materialSlot)
		placeUp()
		placeDown()
		if i == length then
			turtle.turnLeft()
		end
		turtle.back()
		place()
	end
end

turtle.turnLeft()
turtle.turnLeft()
turtle.up()
buildWall(length)
buildWall(length-1)
buildWall(length-1)
buildWall(length-2)