[Wip] turtle excavator v1.0

local args = {...}

local width = tonumber(args[1])
local height = tonumber(args[2])
local depth = tonumber(args [3])

if table.getn(args) < 3 then
  print('Usage: ' .. shell.getRunningProgram() .. ' <width> <length> <depth>')
  error()
end

if width == nil or height == nil or depth == nil then
  print('Dimensions must be numbers')
  error()
end

if width ~= math.floor(width) or height ~= math.floor(height) or depth ~= math.floor(depth) then
  print('Dimensions must be whole numbers')
  error()
end

if width < 1 or height < 1 or depth < 1 then
  print('All dimensions must be at least 1')
  error()
end

local x = 0
local y = 0 --in minecraft y is really z but the turtles coords are relative to itself so it doesnt matter
local z = 0
local orient = 1 -- 1 = default, goes clockwise
local useEnderChest = false

local xDiff = {0, 1, 0, -1}
local yDiff = {1, 0, -1, 0}

if turtle.getItemCount(1) == 1 then
    useEnderChest = true
end

local function hasSpace()
    for n = 1, 16 do
        if turtle.getItemCount(n) == 0 then
            return true
        end
        sleep(0)
    end

    return false
end

local function dumpItems(dir, force)
    if not useEnderChest then
return
end
    if hasSpace() and not force then
        return
    end

    local place = turtle.place
    local dig = turtle.dig
    local drop = turtle.drop
    local detect = turtle.detect

    if dir == "up" then
        place = turtle.placeUp
        dig = turtle.digUp
        drop = turtle.dropUp
        detect = turtle.detectUp
    elseif dir == "down" then
        place = turtle.placeDown
        dig = turtle.digDown
        drop = turtle.dropDown
        detect = turtle.detectDown
    end

        while detect() and not dig() do end

        turtle.select(1)

        while not place() do end

    for n = 1, 16 do
        turtle.select(n)
        drop()
    end

    turtle.select(1)
    while not dig() do end
end

local function forward()
  x = x + xDiff[orient + 1]
  y = y + yDiff[orient + 1]

  moved = turtle.forward()

  while not moved do
    turtle.attack()
    if turtle.getFuelLevel() == 0 then
        print('Out of fuel\nWaiting for fuel in slot 2...')
        turtle.select(2)
        while turtle.getFuelLevel() == 0 do
           turtle.refuel()
        end
    print('Fuel level is: ' .. turtle.getFuelLevel())
    end
    if turtle.detect() then turtle.dig() dumpItems() end
    moved = turtle.forward()
  end

  if z > -depth + 1 and turtle.detectDown() then turtle.digDown() dumpItems("down")  end
  if turtle.detectUp() then turtle.digUp() dumpItems("up")  end
end

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

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

local function up()
  if turtle.detectUp() then turtle.digUp() dumpItems("up")  end
  moved = turtle.up()
  if not moved then
    repeat
        if turtle.detectUp() then turtle.digUp() dumpItems("up")  end
        moved = turtle.up()
    until moved
  end

  z = z + 1
  if turtle.detectUp() and z < height -1 then turtle.digUp() dumpItems("up")  end
end

local function down()
  local dug = true

  if turtle.detectDown() then turtle.digDown() dumpItems("down") end
  moved = turtle.down()
  if not moved then
    repeat
        if turtle.detectDown() then dug = turtle.digDown() dumpItems("down") end
        if not dug then --bedrock
        dumpItems(nil, true)
        error()
        end
        moved = turtle.down()
    until moved
  end

  z = z - 1
  if turtle.detectDown() and z > -depth + 1 then turtle.digDown() dumpItems("down")  end
end

local function isEven(n)
  return n % 2 == 0
end

local function round(n) -- rounds numbers
  return math.floor(n + 0.5)
end

local function turn(n)
  if n % 2 == 0 then left()
  else right() end
end

local function digStrip()
  for n=0, height-2 do
    forward()
  end
end

local function digLayer()
  for n = 0, width-1 do
    if n ~= width-1  then
      digStrip()
      turn(n)
      forward()
      turn(n)
    end
  end
  digStrip()
  if width % 2 ~= 0 then left() end

  for n = 1, 3 do
    if z > -depth + 1 then down() end
  end
end

local function digCube()
  if depth > 1 then down() end

  for n = 1, (round((depth + 1)/3)*3)/3 do
    digLayer()
    left()
  end
end

if width % 2 == 0 then
  width, height = height, width
  for n=0, width-2 do forward() end
  left()
  orient = 1
  x, y = 0, 0
end

digCube()

dumpItems(nil, true)