after.ex

defmodule Auth do
  ## IMPERATIVE SHELL
  def login(email, input_password) do
    with {:ok, user} <- UserRepo.find_by_email(email),
    	 {:allowed, true} <- {:allowed, is_allowed(user, input_password)} do
           UserRepo.update_last_login_date(user, DateTime.utc_now())
	   {:ok, user}
    else
      _ -> :error
    end
  end
  
  ## FUNCTIONAL CORE
  defp is_allowed(user, input_password) do
    password_hash = BCrypt.hash(input_password)
    cond do
      user.hash != hash       -> false
      user.active == false    -> false
      user.deleted_at != nil  -> false 
      true                    -> true
    end
  end
end