defmodule Odinsea.Game.ShopItem do
  @moduledoc """
  Represents an item listed in a player shop or hired merchant.
  Ported from src/server/shops/MaplePlayerShopItem.java

  Each shop item contains:
  - The actual item data
  - Number of bundles (how many stacks)
  - Price per bundle
  """

  alias Odinsea.Game.{Item, Equip}

  @type t :: %__MODULE__{
          item: Item.t() | Equip.t(),
          bundles: integer(),
          price: integer()
        }

  defstruct [
    :item,
    :bundles,
    :price
  ]

  @doc """
  Creates a new shop item.
  """
  def new(item, bundles, price) do
    %__MODULE__{
      item: item,
      bundles: bundles,
      price: price
    }
  end

  @doc """
  Calculates the total quantity available (bundles * quantity per bundle).
  """
  def total_quantity(%__MODULE__{} = shop_item) do
    per_bundle = shop_item.item.quantity
    shop_item.bundles * per_bundle
  end

  @doc """
  Calculates the total price for a given quantity.
  """
  def calculate_price(%__MODULE__{} = shop_item, quantity) do
    shop_item.price * quantity
  end

  @doc """
  Reduces the number of bundles by the given quantity.
  Returns the updated shop item.
  """
  def reduce_bundles(%__MODULE__{} = shop_item, quantity) do
    %{shop_item | bundles: shop_item.bundles - quantity}
  end

  @doc """
  Checks if the item is sold out (no bundles remaining).
  """
  def sold_out?(%__MODULE__{} = shop_item) do
    shop_item.bundles <= 0
  end

  @doc """
  Creates a copy of the item for the buyer.
  The copy has the quantity adjusted based on bundles purchased.
  """
  def create_buyer_item(%__MODULE__{} = shop_item, quantity) do
    item_copy = copy_item(shop_item.item)
    per_bundle = shop_item.item.quantity
    total_qty = quantity * per_bundle

    case item_copy do
      %{quantity: _} = item ->
        %{item | quantity: total_qty}

      equip ->
        # Equipment doesn't have quantity field
        equip
    end
  end

  defp copy_item(%Item{} = item), do: Item.copy(item)
  defp copy_item(%Equip{} = equip), do: Equip.copy(equip)
  defp copy_item(item), do: item

  @doc """
  Removes karma flags from an item (for trade).
  """
  def remove_karma(%__MODULE__{} = shop_item) do
    item = shop_item.item

    updated_item =
      cond do
        # KARMA_EQ flag = 0x02
        Bitwise.band(item.flag, 0x02) != 0 ->
          %{item | flag: item.flag - 0x02}

        # KARMA_USE flag = 0x04
        Bitwise.band(item.flag, 0x04) != 0 ->
          %{item | flag: item.flag - 0x04}

        true ->
          item
      end

    %{shop_item | item: updated_item}
  end
end