defmodule WalletPasses do
  @moduledoc """
  Apple Wallet and Google Wallet pass generation, management, and remote updates.

  This module provides convenience functions that orchestrate both platforms.
  For platform-specific control, use `WalletPasses.Apple.Builder`,
  `WalletPasses.Google.Api`, etc. directly.
  """

  alias WalletPasses.Apple
  alias WalletPasses.Google
  alias WalletPasses.PassData
  alias WalletPasses.PassType
  alias WalletPasses.Schema

  @doc """
  Generates an Apple .pkpass binary for a pass.

  Creates or retrieves the Apple pass record, then builds the .pkpass bundle.
  """
  def build_apple_pass(%PassData{} = pass_data, %Apple.Visual{} = visual) do
    with {:ok, apple_pass} <- Schema.get_or_create_apple_pass(pass_data.serial_number) do
      Apple.Builder.build_pkpass(pass_data, visual, apple_pass.auth_token)
    end
  end

  @doc """
  Generates a "Save to Google Wallet" URL for a pass.

  Creates or retrieves the Google pass record, creates/updates the object
  on Google's servers, and returns the save URL.

  ## Options

    * `:class_id` — Class ID suffix to use for the object (defaults to the
      pass type's standard suffix).
    * `:class_config` — Map of class configuration. When provided, ensures
      the class exists on Google's servers (idempotent — only created once
      per VM lifetime per class). The map's `:id` key defaults to the
      `:class_id` opt or to the pass type's standard suffix.
    * `:origins` — Passed through to `Google.SaveUrl`.
  """
  def google_save_url(%PassData{} = pass_data, %Google.Visual{} = visual, opts \\ []) do
    {class_id, opts} = Keyword.pop(opts, :class_id)
    {class_config, save_opts} = Keyword.pop(opts, :class_config)

    with :ok <- maybe_ensure_class(class_config, class_id, pass_data.pass_type),
         {:ok, google_pass} <- Schema.get_or_create_google_pass(pass_data.serial_number),
         {:ok, object_id} <- Google.Api.create_object(pass_data, visual, class_id: class_id) do
      Schema.update_google_object_id(google_pass, object_id)
      pass_object = Google.Api.build_pass_object(pass_data, visual, class_id: class_id)
      Google.SaveUrl.url(pass_object, save_opts)
    end
  end

  @doc "Sends Apple push notifications for a pass to trigger refresh on devices."
  def notify_apple_devices(serial_number) when is_binary(serial_number) do
    tokens = Schema.list_push_tokens_for_serial(serial_number)
    Apple.Push.notify_devices(tokens)
  end

  @doc """
  Updates a Google Wallet pass object on Google's servers.

  ## Options

    * `:class_id` — Pass-through to `Google.Api.update_object`.
    * `:class_config` — Map of class configuration. When provided, ensures
      the class exists on Google's servers (idempotent).
  """
  def update_google_pass(%PassData{} = pass_data, %Google.Visual{} = visual, opts \\ []) do
    {class_id, opts} = Keyword.pop(opts, :class_id)
    {class_config, update_opts} = Keyword.pop(opts, :class_config)

    with :ok <- maybe_ensure_class(class_config, class_id, pass_data.pass_type) do
      case Schema.get_google_pass(pass_data.serial_number) do
        nil ->
          {:error, :not_found}

        google_pass when is_nil(google_pass.object_id) ->
          {:error, :no_object_id}

        google_pass ->
          Google.Api.update_object(
            pass_data,
            visual,
            google_pass.object_id,
            Keyword.put(update_opts, :class_id, class_id)
          )
      end
    end
  end

  @doc """
  Returns wallet presence for a pass across both platforms.

    * `:apple` — `true` when the pass has at least one device registration.
      Note: this is a "reachable for push" signal, not a "user has the pass"
      signal — see `WalletPasses.EventHandler.on_pass_removed/3` for the
      caveats around iOS push-token rotation and app uninstall.

    * `:google` — `true` when the latest recorded callback for the pass is
      `save`, `false` if `del`, and `nil` if no callback has been received
      (either the pass was never saved, or the consumer doesn't have
      `:google_callback_url` configured).
  """
  @spec wallet_presence(String.t()) :: %{apple: boolean(), google: boolean() | nil}
  def wallet_presence(serial_number) when is_binary(serial_number) do
    %{
      apple: Schema.has_device_registrations?(serial_number),
      google: google_wallet_presence(serial_number),
    }
  end

  defp google_wallet_presence(serial_number) do
    case Schema.latest_google_callback(serial_number) do
      nil -> nil
      %{event_type: "save"} -> true
      %{event_type: "del"} -> false
    end
  end

  defp maybe_ensure_class(nil, _class_id, _pass_type), do: :ok

  defp maybe_ensure_class(class_config, class_id, pass_type) when is_map(class_config) do
    default_id = class_id || PassType.google_class_suffix(pass_type)
    config = Map.put_new(class_config, :id, default_id)
    Google.Api.ensure_class(config, pass_type)
  end
end