Ingot-Recraft (requires Crafty-Turtle)

local version = 0.3
--  +------------------------+  --
--  |-->  INITIALIZATION  <--|  --
--  +------------------------+  --
if not turtle then
  print("This program can only be")
  print("  executed by a turtle!")
  return
end

local ARGS = {...}

-- INITIALIZING NECESSARY FUNCTIONS
local startswith = function(self, piece)
  return string.sub(self, 1, string.len(piece)) == piece
end

-- UPDATE HANDLING --
if _UD and _UD.su(version, "g4Nr4qMA", {...}) then return end

-- directions in relation to initial placement (which is 0, or front)
local direction = {front=0, right=1, back=2, left=3, top=4, bottom=5 }

-- INITIAL VARIABLE SETUP --
local vars = {
  -- width and height of the quarry site
  dropside = direction.bottom,
  tempside = direction.top,
  fetchside = direction.front,
  facing = direction.front
}

-- READ OUT COMMAND LINE PARAMETERS --
for _,par in pairs(ARGS) do
  if startswith(par, "d:") then
    vars.dropside = direction[string.sub(par, string.len("d:")+1)]
  elseif startswith(par, "t:") then
    vars.tempside = direction[string.sub(par, string.len("t:")+1)]
  elseif startswith(par, "f:") then
    vars.fetchside = direction[string.sub(par, string.len("f:")+1)]
  elseif par == "help" then
    print("The Turtle will suck ingots from the specified side (default: front) and craft them to nuggets which will be temporarily dropped to the \"temp\" side (default: top).")
    print("The nuggets will be crafted back to ingots and get dropped to the \"drop\" side (default: bottom).")
    print("Usage: "..shell.getRunningProgram().." [f:{fetch side}] [t:{temp side}] [d:{frop side}]")
    print("   For example: "..shell.getRunningProgram().." f:top t:back")
    return
  end
end

local function turnLeft()
  turtle.turnLeft()
  vars.facing = vars.facing-1
  if (vars.facing < 0) then
    vars.facing = 3
  end
end

-- drops to the designated side and returns whatever the turtle.drop returns.
local function drop( side )
  if side == direction.top then
    return turtle.dropUp()
  elseif side == direction.bottom then
    return turtle.dropDown()
  else
    while vars.facing ~= side do
      turnLeft()
    end
    return turtle.drop()
  end
end

-- sucks from the designated side and returns whatever the turtle.suck returns.
local function suck( side )
  if side == direction.top then
    return turtle.suckUp()
  elseif side == direction.bottom then
    return turtle.suckDown()
  else
    while vars.facing ~= side do
      turnLeft()
    end
    return turtle.suck()
  end
end

local function status(text)
  term.clear()
  term.setCursorPos(1,1)
  print(" Ingot-Recraft ")
  print("---------------")
  print()
  term.write("--> ")
  print(text)
  print()
end

local function main()
  status("Dropping Inventory...")
  for i=1,16 do
    if turtle.getItemCount(i) > 0 then
      turtle.select(i)
      drop(vars.dropside)
    end
  end

  turtle.select(1)
  suck(vars.fetchside)

  while turtle.getItemCount(1) > 0 do
    local ingotCount = turtle.getItemCount(1)
    -- TODO: check if valid ingots
    status("Crafting ingots to nuggets...")
    turtle.select(2)
    while turtle.getItemCount(1) > 0 do
      turtle.craft()
      drop(vars.tempside)
    end

    status("Crafting back to ingots...")
    turtle.select(16)
    for i=1,11 do
      if (i%4) > 0 then
        -- always sucking to slot 16 and then evenly distributing to the 9 crafting slots
        turtle.transferTo(i, ingotCount)
        local nuggetsNeeded = ingotCount - turtle.getItemCount(i)
        if (nuggetsNeeded > 0) then
          suck(vars.tempside)
          turtle.transferTo(i,nuggetsNeeded)
        end
      end
    end
    turtle.craft()

    status("Dropping Inventory...")
    for i=1,16 do
      if turtle.getItemCount(i) > 0 then
        turtle.select(i)
        drop(vars.dropside)
      end
    end

    turtle.select(1)
    suck(vars.fetchside)
  end

  status("Finished.")
end

main()