Turtle Item Repairer

-- User configurable
local CHECK_DELAY = 60 -- Delay between each batch crafting operation.
local BUFFER_DELAY_REMOVAL = 5 -- Time subtracted from the delay-between-crafting-operations per item that had to be stored in the buffer chest. Default case = 5 with 60 delay will mean 12 items in the buffer chest will cause the crafting operation to instantly resume.
local INPUT_CHEST = "minecraft:shulker_box_0" -- The input chest's (or other inventory) name on the network.
local OUTPUT_CHEST = "minecraft:shulker_box_1" -- The output chest's (or other inventory) name on the network.
local BUFFER_CHEST = "minecraft:chest_1" -- A third chest (or other inventory) on the network. The turtle will move things here temporarily if the input inventory is full and it cannot push damaged items back into it.
local ERROR_DELAY = 2 -- Delay between retries if an error occurs (ie: failing to move items to the output inventory)

-- Don't touch
local modem = peripheral.wrap("front") --[[@as WiredModem]]
if not modem or not modem.getNameLocal or not modem.getNameLocal() then
  error("Expected activated wired modem in front!", 0)
end
local local_name = modem.getNameLocal() --[[@as string we have already verified this will return an appropriate value]]

local inv = peripheral.wrap(INPUT_CHEST) --[[@as Inventory]]
if not inv or not inv.list then
  error("Expected input inventory on network!", 0)
end

local output = peripheral.wrap(OUTPUT_CHEST) --[[@as Inventory]]
if not output or not output.list then
  error("Expected output inventory to be on the network!", 0)
end

local buffer = peripheral.wrap(BUFFER_CHEST) --[[@as Inventory]]
if not buffer or not buffer.list then
  error("Expected buffer inventory to be on the network!", 0)
end

--- Grab an item from the input inventory and move it to the turtle.
---@param slot integer The slot to pull from.
local function get_item(slot)
  print("Pulling item from input slot", slot, "to the turtle.")
  return inv.pushItems(local_name, slot)
end

--- Move item in the turtle to the output chest, if fully repaired.
---@return boolean outputted If the item was outputted (ie: was fully repaired).
local function attempt_output()
  for slot = 1, 16 do
    -- Need detailed mode for damage.
    local item = turtle.getItemDetail(slot, true) --[[@as turtleDetailsDetailed|nil]]
    if item then
      if item.damage == 0 then
        -- To the output chest!
        print("Pulling repaired item from turtle.")
        -- While we fail to move items, display an error.
        while output.pullItems(local_name, slot) == 0 do
          printError("Output chest is likely full. Cannot do anything until it is emptied!")
          sleep(ERROR_DELAY)
        end

        print("Successfully repaired and outputted an item.")
        return true
      end
    end
  end

  return false
end

local function force_output()
  for slot = 1, 16 do
    -- Need detailed mode for damage.
    local item = turtle.getItemDetail(slot, true) --[[@as turtleDetailsDetailed|nil]]
    if item then
      -- To the output chest!
      print("Pulling item from turtle to output chest.")
      while output.pullItems(local_name, slot) == 0 do
        printError("Output chest is likely full. Cannot do anything until it is emptied!")
        sleep(ERROR_DELAY)
      end
    end
  end
end

--- Empty the buffer chest
---@return integer buffered The amount of items that were taken out of the buffer.
local function empty_buffer()
  local buffered = 0

  for slot, item in pairs(buffer.list()) do
    buffered = buffered + item.count
    inv.pullItems(BUFFER_CHEST, slot)
  end

  return buffered
end

--- Dump the contents of the turtle to the buffer chest
---@return integer buffered The amount of items that were taken out of the buffer, if the buffer needed to be emptied during this cycle.
local function dump_to_buffer()
  local buffered = 0

  for slot = 1, 16 do
    if turtle.getItemCount(slot) > 0 then
      if buffer.pullItems(local_name, slot) == 0 then
        buffered = buffered + empty_buffer()
        while buffer.pullItems(local_name, slot) == 0 do
          printError("Buffer chest and input chest are likely full. Cannot do anything until they are emptied!")
          sleep(ERROR_DELAY)
        end
      end
    end
  end

  return buffered
end

while true do
  local size = inv.size()
  local repairs = 0
  local full_health = 0
  local buffered = 0
  for test_slot = 1, size - 1 do
    -- Get the item in that slot.
    local item = inv.getItemDetail(test_slot)

    if item then
      -- An item exists in this slot.

      -- Then, check if we even need to combine this item with anything...
      if item.damage == 0 then
        print("Found an undamaged item in the chest, moving it to output.")
        full_health = full_health + 1
        while output.pullItems(INPUT_CHEST, test_slot) == 0 do
          printError("Output chest is likely full. Cannot do anything until it is emptied!")
          sleep(ERROR_DELAY)
        end
      else -- Item is damaged,
        get_item(test_slot)

        -- we will try to combine it until we can no longer do so.
        for secondary_slot = test_slot + 1, size do
          -- Get the item in that slot
          local second_item = inv.getItemDetail(secondary_slot)

          if second_item then
            -- First, check if the item is undamaged already (it's a waste to craft these).
            if second_item.damage == 0 then
              -- Move it to the output chest if undamaged.
              print("Found an undamaged item in the chest, moving it to output.")
              full_health = full_health + 1
              while output.pullItems(INPUT_CHEST, secondary_slot) == 0 do
                printError("Output chest is likely full. Cannot do anything until it is emptied!")
                sleep(ERROR_DELAY)
              end
            elseif item.name == second_item.name then -- Check if the two item names are equal.
              -- Items are the same!
              get_item(secondary_slot)
              if not turtle.craft() then
                printError("Items were not craftable!")
                print("Moving them into the output chest.")
                force_output()
                -- We do not break out of the loop here: if more of this item remain, it will get pulled and moved to the output immediately.
              end

              -- And if we were able to output this item, break out of this inner loop.
              if attempt_output() then
                repairs = repairs + 1
                break
              end
            end
          end
        end

        -- If we went through all the items in the chest and failed to repair it, throw it into the buffer chest.
        buffered = buffered + dump_to_buffer()
      end
    end
  end

  -- Empty the contents of the buffer inventory into the main inventory.
  buffered = buffered + empty_buffer()

  print(("Done cycle.\n  Successful repairs: %d\n  Full-health items found: %d\n  Items buffered: %d\n  Time until next cycle: %d seconds"):format(
    repairs,
    full_health,
    buffered,
    math.max(CHECK_DELAY - BUFFER_DELAY_REMOVAL * buffered, 0)
  ))
  sleep(math.max(CHECK_DELAY - BUFFER_DELAY_REMOVAL * buffered, 0))
end