defmodule HubIdentityElixir.Authentication do
  import Plug.Conn
  import Phoenix.Controller

  def fetch_current_user(conn, _opts) do
    current_user = get_session(conn, :current_user)
    assign(conn, :current_user, current_user)
  end

  def log_in_user(conn, current_user) do
    user_return_to = get_session(conn, :user_return_to)

    conn
    |> renew_session()
    |> put_session(:current_user, current_user)
    |> assign(:current_user, current_user)
    |> redirect(to: user_return_to || signed_in_path(conn))
  end

  @doc """
  Logs the user out.

  It clears all session data for safety. See renew_session.
  """
  def log_out_user(conn) do
    conn
    |> renew_session()
    |> redirect(to: "/")
  end

  @doc """
  Used for routes that require the user to be authenticated.

  If you want to enforce the user email is confirmed before
  they use the application at all, here would be a good place.
  """
  def require_authenticated_user(conn, _opts) do
    if conn.assigns[:current_user] do
      conn
    else
      conn
      |> put_flash(:error, "You must log in to access this page.")
      |> maybe_store_return_to()
      |> redirect(to: "/sessions/new")
      |> halt()
    end
  end

  defp maybe_store_return_to(%{method: "GET"} = conn) do
    put_session(conn, :user_return_to, current_path(conn))
  end

  defp maybe_store_return_to(conn), do: conn

  # This function renews the session ID and erases the whole
  # session to avoid fixation attacks. If there is any data
  # in the session you may want to preserve after log in/log out,
  # you must explicitly fetch the session data before clearing
  # and then immediately set it after clearing, for example:
  #
  #     defp renew_session(conn) do
  #       preferred_locale = get_session(conn, :preferred_locale)
  #
  #       conn
  #       |> configure_session(renew: true)
  #       |> clear_session()
  #       |> put_session(:preferred_locale, preferred_locale)
  #     end
  #
  defp renew_session(conn) do
    conn
    |> configure_session(renew: true)
    |> clear_session()
    |> assign(:current_user, nil)
  end

  defp signed_in_path(_conn), do: "/"
end