-- dig a cube
-- starts from the bottom-left-front corner (not in the cube)

local mv = require("movement")

local function dropStuffOff()
  local prev_pos,prev_face = mv.getPosition()
  mv.goBackTo(0,0,0)
  mv.face(0, -1)
  mv.dumpInventory()
  mv.goBackTo(prev_pos.x, prev_pos.y, prev_pos.z)
  mv.face(prev_face.x, prev_face.z)
end

local function superDig()
  mv.dig()
  mv.forward()
  mv.digUp()
  mv.digDown()

  if mv.isInventoryFull() then dropStuffOff() end
end

local function doFullLayer(width, depth)
  for i=1,width do
    mv.nTimes(depth-1, superDig)
    local turn = mv.turnLeft
    if i%2 == 1 then turn = mv.turnRight end
    if i ~= width then
      turn()
      superDig()
      turn()
    end
  end

  if width%2 == 1 then
    mv.turnAround()
    mv.nTimes(depth-1, mv.forward)
  end
  mv.turnRight()
  mv.nTimes(width-1, mv.forward)
  mv.turnRight()
end

local function digCube(depth, height, width)
  local gid_down = height < 0
  if gid_down then height = -height end
  -- fun fact: -3 is exactly the same as +3

  if height < 3 or width <= 0 or depth <= 0 then
    print("sorry, your cube is too small")
    return
  end

  local need_space = width*height*depth/64
  print(string.format("we will need %d free slots", need_space))

  local function digLayers(up)
    for i=1,height/3 do
      if i ~= 1 then up() end
      up()
      doFullLayer(width, depth)
      up()
    end
    if height%3 > 0 then
      if height%3 == 2 then up() end
      doFullLayer(width, depth)
      up()
    end
    mv.goBackTo(0,0,0)
    mv.face(1,0)
    dropStuffOff()
  end

  mv.forward()
  if gid_down then
    while not turtle.detectDown() and height > 3 do
      mv.down()
      height = height - 1
    end
    mv.up()
    mv.up()
    digLayers(mv.down)
  else
    digLayers(mv.up)
  end
end

local function main(args)
  if #args == 0 then
    digCube(8,8,8)
  elseif #args == 1 then
    local n = tonumber(args[1])
    digCube(n,n,n)
  elseif #args == 3 then
    digCube(tonumber(args[1]), tonumber(args[2]), tonumber(args[3]))
  else
    print("usage: cube [depth] [height] [width]")
    print("got the wrong number of args...")
  end
end

local args = {...}
main(args)