stairs2

local tArgs = {...}

local width  = tonumber(tArgs[1])
local length = tonumber(tArgs[2])
local depth  = tonumber(tArgs[3])


local dir = 0
local NORTH,EAST,SOUTH,WEST = 0,1,2,3
local INPUT_PIPE = 1
local TRANSPORT_PIPE = 2



if width > 0 and length > 0 and depth > 0 then
  print ("Digging a "..tostring(width)
         .." x "..tostring(length)
         .." x "..tostring(depth)
         .." square.")
end

local function refuel()
  if turtle.getFuelLevel() < 20 then
    local i=1
    while not turtle.refuel(i) do
      turtle.select(i)
      i = i + 1
      if i > 16 then
        print("Need fuel to continue...")
      break
      end
    end
  end
end


local function forward()
  while turtle.detect() do
    turtle.dig()
  end
  refuel()
  turtle.forward()
end

local function turnRight()
  turtle.turnRight()
  dir = (dir + 1) % 4
end

local function turnLeft()
  turtle.turnLeft()
  dir = (dir - 1) % 4
end

local function face(d)

 local delta = (d - dir) % 4

 if delta == 0 then
   return
 elseif delta == 1 then
   turnRight()
 elseif delta == 2 then
   turnRight()
   turnRight()
 elseif delta == 3 then
   turnLeft()
 end
end

local function placePipe(n)
  turtle.select(n)
  turtle.place()
end

local function placeInputPipe()
  placePipe(INPUT_PIPE)
end

local function placeTransportPipe()
  placePipe(TRANSPORT_PIPE)
end

local function minePipe()
  turtle.select(1)
  turtle.dig()
end

local function unload()
  face(WEST)
  placeInputPipe()
  turtle.up()
  turtle.up()
  forward()

  for i=3,16 do
    turtle.select(i)
    turtle.dropDown()
  end

  turtle.back()
  turtle.down()
  placeTransportPipe()
  turtle.down()
  minePipe()
  placeTransportPipe()
end

local function digRow(n)
  for i=1,n-1 do
    turtle.dig()
    forward()
  end
end

local function advanceRowOdd()
  face(EAST)
  turtle.dig()
  forward()
  face(NORTH)
end

local function advanceRowEven()
 face(EAST)
 turtle.dig()
 forward()
 face(SOUTH)
end

local function advanceLevel()
 unload()
 turtle.digDown()
 turtle.down()
 forward()
 face(NORTH)

end

local function startingPoint(x,y)
  face(WEST)
  digRow(x-1)
  if width % 2 == 1 then
    face(SOUTH)
    digRow(y)
  end
end

local function digSquare(x,y)
  for i=1,x do
    digRow(y)
  if i ~= x then
    if i % 2 == 0 then
      advanceRowOdd()
    else
      advanceRowEven()
    end
  end
  end
  startingPoint(x,y)
end

local function digStairs(x,y,z)
  for i=1, z do
    digSquare(x,y)
    advanceLevel()
  end
end

function main()
  digStairs(width,length,depth)
  print("Mine Complete")
end

main()