defmodule Mv.Membership.JoinNotifier do
  @moduledoc """
  Behaviour for sending join-related emails (confirmation, already member, already pending).

  The domain calls this module instead of MvWeb.Emails directly, so the domain layer
  does not depend on the web layer. The default implementation is set in config
  (`config :mv, :join_notifier, MvWeb.JoinNotifierImpl`). Tests can override with a mock.
  """
  @callback send_confirmation(email :: String.t(), token :: String.t(), opts :: keyword()) ::
              {:ok, term()} | {:error, term()}
  @callback send_already_member(email :: String.t()) :: {:ok, term()} | {:error, term()}
  @callback send_already_pending(email :: String.t()) :: {:ok, term()} | {:error, term()}
end