defmodule MapkitJS do
  @moduledoc """
  Elixir client for Apple MapKit JS token generation.

  MapKit JS uses an ES256 JWT that your web app passes to `mapkit.init/1`.
  This library focuses on generating and caching that JWT.

  The public surface is intentionally small:

      MapkitJS.token()
      MapkitJS.generate_token(origin: "https://example.com")
      MapkitJS.authorization_callback_payload()

  ## Configuration

      config :mapkit_js,
        team_id: System.get_env("APPLE_TEAM_ID"),
        key_id: System.get_env("MAPKIT_KEY_ID"),
        private_key: System.get_env("MAPKIT_PRIVATE_KEY"),
        origin: System.get_env("MAPKIT_ORIGIN")

  Every function also accepts per-call `opts` that override the application config.
  """

  alias MapkitJS.{Config, Token}

  @type opts :: keyword()

  @doc "Return a MapKit JS JWT using the configured token cache behavior."
  @spec token(opts) :: {:ok, String.t()} | {:error, term()}
  def token(opts \\ []) do
    Token.access_token(opts)
  end

  @doc "Generate a new MapKit JS JWT."
  @spec generate_token(opts) :: {:ok, String.t()} | {:error, term()}
  def generate_token(opts \\ []) do
    Token.generate_jwt(opts)
  end

  @doc "Return the payload commonly passed into a browser-side `authorizationCallback`."
  @spec authorization_callback_payload(opts) :: {:ok, map()} | {:error, term()}
  def authorization_callback_payload(opts \\ []) do
    config = Config.load(opts)

    with {:ok, token} <- token(opts) do
      {:ok,
       %{
         token: token,
         expires_in: config.token_ttl_seconds,
         origin: config.origin
       }}
    end
  end
end