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.

  ## Pass Lifecycle

  Passes have a lifecycle status: `:active` (default), `:voided`, `:expired`,
  `:completed`. Use `void_pass/1`, `expire_pass/1`, `complete_pass/1`, and
  `reactivate_pass/1` to transition. Each function:

    * Updates the `status` column on whichever Apple/Google rows exist for the
      serial (transactional — the two rows can't diverge from a DB error).
    * Patches the Google object's `state` field via the Wallet API
      (`ACTIVE`/`INACTIVE`/`EXPIRED`/`COMPLETED`).
    * Triggers Apple device push so devices fetch the updated pass content.

  Returns `{:ok, %{status: status, apple: :ok | :not_found,
  google: :ok | :not_found | {:error, _}}}` even when remote calls fail — the
  DB write is the source of truth, and remote failures are surfaced for
  caller-driven retry rather than silently rolled back. Returns
  `{:error, :not_found}` only when neither an Apple nor a Google row exists.

  `reactivate_pass/1` lets a non-active pass return to `:active`. The library
  does not enforce transition validity; consumers wanting a state machine
  should wrap these calls in their own policy layer.

  For Apple devices to render lifecycle states differently, the
  `PassDataProvider.build_pass_data/1` implementation should inspect
  `WalletPasses.Schema.get_pass_status/1` (or call
  `WalletPasses.PassDataProvider.apply_status_decoration/2`) before returning
  the pass.

  The `:expired` status overlaps with Apple's native `expirationDate` field
  in the `.pkpass`. Use `expire_pass/1` for issuer-driven expiry events
  (refunded ticket, revoked subscription); use `expirationDate` for
  date-based expiry that the OS handles automatically.

  ## Localization

  Pass content can be translated for both platforms via a single `:translations`
  map option:

      translations = %{
        "fr" => %{"Gate" => "Porte", "Section" => "Section"},
        "es" => %{"Gate" => "Puerta"}
      }

      WalletPasses.build_apple_pass(pass_data, visual, translations: translations)
      WalletPasses.google_save_url(pass_data, visual, translations: translations)

  Apple receives `.lproj/pass.strings` entries inside the `.pkpass` ZIP; Google
  receives `LocalizedString` `translatedValues` on the object and class JSON.
  The same map drives both. See the
  [Localization Guide](guides/localization.md) for the full reference.
  """

  alias WalletPasses.Apple
  alias WalletPasses.Config
  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.

  ## Options

    * `:translations` — Passed through to `Apple.Builder.build_pkpass/4`. See the
      [Localization](guides/localization.md) guide.
    * `:localized_images` — Passed through to `Apple.Builder.build_pkpass/4`.
  """
  def build_apple_pass(%PassData{} = pass_data, %Apple.Visual{} = visual, opts \\ []) 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, opts)
    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`.
    * `:translations` — Passed through to `Google.Api.build_pass_object/3` for
      object-level localization. To localize class-level fields, include
      `:translations` inside the `:class_config` map. See the
      [Localization](guides/localization.md) guide.
  """
  def google_save_url(%PassData{} = pass_data, %Google.Visual{} = visual, opts \\ []) do
    {class_id, opts} = Keyword.pop(opts, :class_id)
    {class_config, opts} = Keyword.pop(opts, :class_config)
    {translations, save_opts} = Keyword.pop(opts, :translations)

    builder_opts = [class_id: class_id, translations: translations]

    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, pass_data.pass_type),
         {:ok, object_id} <- Google.Api.create_object(pass_data, visual, builder_opts) do
      Schema.update_google_object_id(google_pass, object_id)
      pass_object = Google.Api.build_pass_object(pass_data, visual, builder_opts)
      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).
    * `:translations` — Passed through to `Google.Api.build_pass_object/3`.
      See the [Localization](guides/localization.md) guide.
  """
  def update_google_pass(%PassData{} = pass_data, %Google.Visual{} = visual, opts \\ []) do
    {class_id, opts} = Keyword.pop(opts, :class_id)
    {class_config, opts} = Keyword.pop(opts, :class_config)
    {translations, update_opts} = Keyword.pop(opts, :translations)

    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 ->
          builder_opts =
            update_opts
            |> Keyword.put(:class_id, class_id)
            |> Keyword.put(:translations, translations)

          Google.Api.update_object(
            pass_data,
            visual,
            google_pass.object_id,
            builder_opts
          )
      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 `c: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

  @type lifecycle_result :: %{
          status: :active | :voided | :expired | :completed,
          apple: :ok | :not_found,
          google: :ok | :not_found | {:error, term()},
        }

  @doc """
  Voids a pass. Updates the DB status for whichever Apple/Google rows exist for
  the serial, patches Google's object state to `INACTIVE`, and pushes Apple
  devices so they refetch the pass.

  Returns `{:ok, lifecycle_result()}` even when remote calls fail — the DB write
  is the source of truth and is never rolled back. Per-platform outcomes are
  reported in the result map. Returns `{:error, :not_found}` only when neither
  an Apple nor a Google row exists for the serial.

  Idempotent.
  """
  @spec void_pass(String.t()) :: {:ok, lifecycle_result()} | {:error, :not_found}
  def void_pass(serial_number), do: transition(serial_number, :voided)

  @doc "Marks a pass as expired on all platforms. See `void_pass/1` for semantics."
  @spec expire_pass(String.t()) :: {:ok, lifecycle_result()} | {:error, :not_found}
  def expire_pass(serial_number), do: transition(serial_number, :expired)

  @doc "Marks a pass as completed (used/redeemed) on all platforms. See `void_pass/1`."
  @spec complete_pass(String.t()) :: {:ok, lifecycle_result()} | {:error, :not_found}
  def complete_pass(serial_number), do: transition(serial_number, :completed)

  @doc "Reactivates a non-active pass. See `void_pass/1` for semantics."
  @spec reactivate_pass(String.t()) :: {:ok, lifecycle_result()} | {:error, :not_found}
  def reactivate_pass(serial_number), do: transition(serial_number, :active)

  defp transition(serial_number, target) when is_binary(serial_number) do
    apple_pass = Schema.get_apple_pass(serial_number)
    google_pass = Schema.get_google_pass(serial_number)

    if is_nil(apple_pass) and is_nil(google_pass) do
      {:error, :not_found}
    else
      {:ok, db_result} = Schema.set_pass_status(serial_number, target)

      google_outcome = handle_google(google_pass, serial_number, target, db_result.google)
      apple_outcome = handle_apple(serial_number, db_result.apple)

      {:ok, %{status: target, apple: apple_outcome, google: google_outcome}}
    end
  end

  defp handle_google(nil, _serial, _target, _db), do: :not_found
  defp handle_google(%{object_id: nil}, _serial, _target, _db), do: :not_found
  defp handle_google(_google_pass, _serial, _target, :not_found), do: :not_found

  defp handle_google(google_pass, serial_number, target, :ok) do
    case resolve_pass_type(google_pass, serial_number) do
      {:ok, pass_type} ->
        google_state = google_state_for(target)

        case Google.Api.update_object_state(pass_type, google_pass.object_id, google_state) do
          {:ok, %{status: s}} when s in 200..299 -> :ok
          {:ok, %{status: s, body: body}} -> {:error, {s, body}}
          {:error, _} = err -> err
        end

      {:error, _} = err ->
        err
    end
  end

  defp handle_apple(_serial, :not_found), do: :not_found

  defp handle_apple(serial_number, :ok) do
    _ = notify_apple_devices(serial_number)
    :ok
  end

  defp google_state_for(:active), do: "ACTIVE"
  defp google_state_for(:voided), do: "INACTIVE"
  defp google_state_for(:expired), do: "EXPIRED"
  defp google_state_for(:completed), do: "COMPLETED"

  defp resolve_pass_type(%{pass_type: pt}, _serial) when is_binary(pt) do
    {:ok, String.to_existing_atom(pt)}
  end

  defp resolve_pass_type(%{pass_type: nil}, serial_number) do
    provider = Config.pass_data_provider()

    case provider.build_pass_data(serial_number) do
      {:ok, %{pass_data: %{pass_type: pt}}} when is_atom(pt) ->
        # Write-through: backfill the column so future transitions skip the lookup.
        {:ok, _} = Schema.get_or_create_google_pass(serial_number, pt)
        {:ok, pt}

      {:ok, _} ->
        {:error, :pass_type_missing_from_provider}

      {:error, reason} ->
        {:error, {:pass_type_lookup_failed, reason}}
    end
  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