embedded_app_plug.ex

defmodule Useless.Plugs.EmbeddedAppPlug do
  @moduledoc """
  Loads the shop from database, puts a private shop field in conn and sets x-frame-options.

  Will halt if no shop found
  """

  alias Plug.Conn
  alias Useless.ShopifyApp

  @doc false
  def init(opts \\ %{}), do: Enum.into(opts, %{})

  @doc false
  def call(%{params: %{"shop" => shopify_domain}} = conn, _opts) do
    shop = ShopifyApp.find_shop_by(%{shopify_domain: shopify_domain})
    allow_shop_or_halt(conn, shop)
  end

  def call(conn, _opts), do: conn

  defp allow_shop_or_halt(conn, nil), do: Conn.halt(conn)

  defp allow_shop_or_halt(conn, shop) do
    conn
    |> Conn.put_private(:shop, shop)
    |> Conn.put_resp_header("x-frame-options", "ALLOW-FROM https://#{shop.shopify_domain}")
  end
end