defmodule Odinsea.Shop.Client do
  @moduledoc """
  Client connection handler for the cash shop server.

  Handles:
  - Cash shop operations (buy, gift, wishlist, etc.)
  - MTS (Maple Trading System) operations
  - Coupon redemption
  - Inventory management
  """

  use GenServer, restart: :temporary

  require Logger

  alias Odinsea.Net.Packet.In
  alias Odinsea.Net.Opcodes
  alias Odinsea.Shop.{Operation, MTS, Packets}
  alias Odinsea.Database.Context

  defstruct [
    :socket,
    :ip,
    :state,
    :character_id,
    :account_id,
    :character,
    :account
  ]

  def start_link(socket) do
    GenServer.start_link(__MODULE__, socket)
  end

  @impl true
  def init(socket) do
    {:ok, {ip, _port}} = :inet.peername(socket)
    ip_string = format_ip(ip)

    Logger.info("Cash shop client connected from #{ip_string}")

    state = %__MODULE__{
      socket: socket,
      ip: ip_string,
      state: :connected,
      character_id: nil,
      account_id: nil,
      character: nil,
      account: nil
    }

    send(self(), :receive)
    {:ok, state}
  end

  @impl true
  def handle_info(:receive, %{socket: socket} = state) do
    case :gen_tcp.recv(socket, 0, 30_000) do
      {:ok, data} ->
        new_state = handle_packet(data, state)
        send(self(), :receive)
        {:noreply, new_state}

      {:error, :closed} ->
        Logger.info("Cash shop client disconnected: #{state.ip}")
        {:stop, :normal, state}

      {:error, reason} ->
        Logger.warning("Cash shop client error: #{inspect(reason)}")
        {:stop, :normal, state}
    end
  end

  @impl true
  def terminate(_reason, state) do
    if state.socket do
      :gen_tcp.close(state.socket)
    end

    :ok
  end

  # ==============================================================================
  # Packet Handling
  # ==============================================================================

  defp handle_packet(data, state) do
    packet = In.new(data)

    case In.decode_short(packet) do
      {opcode, packet} ->
        Logger.debug("Cash shop packet: opcode=0x#{Integer.to_string(opcode, 16)}")
        dispatch_packet(opcode, packet, state)

      :error ->
        Logger.warning("Failed to read packet opcode")
        state
    end
  end

  defp dispatch_packet(opcode, packet, state) do
    cond do
      opcode == Opcodes.cp_player_loggedin() ->
        handle_migrate_in(packet, state)

      opcode == Opcodes.cp_cash_shop_update() ->
        # Cash shop operations
        handle_cash_shop_operation(packet, state)

      opcode == Opcodes.cp_mts_operation() ->
        # MTS operations
        handle_mts_operation(packet, state)

      opcode == Opcodes.cp_alive_ack() ->
        # Ping response - ignore
        state

      true ->
        Logger.debug("Unhandled cash shop opcode: 0x#{Integer.to_string(opcode, 16)}")
        state
    end
  end

  # ==============================================================================
  # Migrate In Handler
  # ==============================================================================

  defp handle_migrate_in(packet, state) do
    {char_id, packet} = In.decode_int(packet)
    {_client_ip, _packet} = In.decode_string(packet) # Skip client IP

    Logger.info("Cash shop migrate in for character #{char_id}")

    # Load character and account
    case Context.get_character(char_id) do
      nil ->
        Logger.error("Character #{char_id} not found")
        :gen_tcp.close(state.socket)
        state

      character ->
        case Context.get_account(character.account_id) do
          nil ->
            Logger.error("Account #{character.account_id} not found")
            :gen_tcp.close(state.socket)
            state

          account ->
            # Load gifts
            gifts = Context.load_gifts(character.id)
            character = %{character | cash_inventory: gifts ++ (character.cash_inventory || [])}

            # Send cash shop setup
            setup_packet = Packets.set_cash_shop(character)
            :gen_tcp.send(state.socket, setup_packet)

            # Send initial update
            Operation.cs_update(state.socket, character)

            %{state |
              state: :in_cash_shop,
              character_id: char_id,
              account_id: account.id,
              character: character,
              account: account
            }
        end
    end
  end

  # ==============================================================================
  # Cash Shop Operation Handler
  # ==============================================================================

  defp handle_cash_shop_operation(packet, state) do
    # Delegate to Operation module
    Operation.handle(packet, state)
  end

  # ==============================================================================
  # MTS Operation Handler
  # ==============================================================================

  defp handle_mts_operation(packet, state) do
    # Delegate to MTS module
    MTS.handle(packet, state)
  end

  # ==============================================================================
  # Utility Functions
  # ==============================================================================

  defp format_ip({a, b, c, d}) do
    "#{a}.#{b}.#{c}.#{d}"
  end

  defp format_ip({a, b, c, d, e, f, g, h}) do
    "#{a}:#{b}:#{c}:#{d}:#{e}:#{f}:#{g}:#{h}"
  end
end