It is a matter of having a custom state to differentiate between which to show…login or signup…you definitely want both to be available so that any user who is not signed up can do so easily and vice versa…also want to have a forgot password button available.

You can check out my template for login signup…it also includes an email redirect system so that a user who requests to reset their password will receive an email to follow for resetting their password and afterward will automatically be redirected back to the page they were on when they first attempted to login.