admin.ex

def require_admin_user(conn, _opts) do
  current_user = conn.assigns[:current_user]

  if current_user.admin? do
    conn
  else
    conn
    |> put_flash(:error, "You must be an admin to access this page.")
    |> redirect(to: Routes.admin_session_path(conn, :new))
    |> halt()
  end
end

def on_mount(:require_admin_user, _params, session, socket) do
  socket = mount_current_user(session, socket)

  if socket.assigns.current_user.admin? do
    {:cont, socket}
  else
    {:halt, Phoenix.LiveView.redirect(socket, to: Routes.user_session_path(socket, :new))}
  end
end

auth.ex

def require_authenticated_user(conn, _opts) do
  cond do
    conn.assigns[:current_user] && conn.assigns[:current_user].confirmed_at ->
      conn

    conn.assigns[:current_user] && !conn.assigns[:current_user].confirmed_at ->
      conn
      |> put_flash(:error, "You must confirm your email before you can access this page.")
      |> redirect(to: Routes.user_confirm_path(conn, :index))
      |> halt()

    true ->
      conn
      |> put_flash(:error, "You must log in to access this page.")
      |> maybe_store_return_to()
      |> redirect(to: Routes.user_session_path(conn, :new))
      |> halt()
  end
end

def require_unconfirmed_user(conn, _opts) do
  cond do
    conn.assigns[:current_user] && !conn.assigns[:current_user].confirmed_at ->
      conn

    conn.assigns[:current_user] && conn.assigns[:current_user].confirmed_at ->
      conn
      |> put_flash(:error, "Your email address is already confirmed.")
      |> redirect(to: Routes.page_path(conn, :index))
      |> halt()
  end
end