Spiral TurtleDig

local args = {...}

if not #args == 3 then
  print("Usage: Args start x,y,z")
  return
end

local spiralSize = 4
local bottom = -58

local x, y, z = gps.locate(5)

if not x then
	print("co-ord get failed")
else
	print("start co-ord " .. x .. ", " .. y .. ", " .. z)
end

function returnStart()
	local facing = 0
	while not turtle.forward() do turtle.dig() end
	local  a,b,c = gps.locate(5)
	if x-a == -1 then
		facing = 1
	elseif z-c == 1 then
		facing = 2
	elseif x-a == 1 then
		facing = 3
	else
		facing = 0
	end

	turtle.turnRight()
	turtle.turnRight()
	while not turtle.forward() do turtle.dig() end
	facing = (facing)%4
	print("facing = " .. facing)
	turtle.turnRight()
	turtle.turnRight()

	for i=0,facing do
		turtle.turnRight()
	end

	local xMove = x - args[1]
	local zMove = args[3] - z

	print(xMove)
	print(zMove)

	for i=0, xMove-1 do
		while not turtle.forward() do turtle.dig() end
	end
	turtle.turnLeft()
	for i=0, zMove-1 do
		while not turtle.forward() do turtle.dig() end
	end

	turtle.turnRight()
	turtle.turnRight()
end

function checkInv()
  isFull = true

  for i=1,15 do
    if turtle.getItemCount(i) == 0 then
      isFull = false
    end
  end

  if isFull == true then
	emptyInv()
  end
end

function emptyInv()
    turtle.select(16)
	while turtle.detectUp() do
      turtle.digUp()
      sleep(0.2)
    end
	turtle.up()
    while not turtle.placeDown() do turtle.digDown() end
    for i=1,15 do
        turtle.select(i)
        turtle.dropDown()
    end
    turtle.select(16)
    turtle.digDown()
    sleep(0.1)
    turtle.select(1)
	turtle.down()
end

function mineLayer()
	local spiralCount = spiralSize
	for i=1,spiralSize do
		for j=1,4 do
			for k=1,spiralCount do
				while not turtle.forward() do turtle.dig() end
			end
			turtle.turnRight()
			checkInv()
		end
		spiralCount = spiralCount - 2
		turtle.turnRight()
		turtle.forward()
		turtle.turnLeft()
	end
end

returnStart()
for l=bottom,args[2] do
	mineLayer()
	while turtle.detectDown() do
      turtle.digDown()
    end
	turtle.down()
end
emptyInv()