@abstract
class_name AuthProvider
extends RefCounted
## How the server learns who a client is.
##
## Modelled on Steamworks deliberately, so swapping to it later is one subclass
## and no schema change: the client obtains an opaque ticket, sends it with the
## handshake, and the server validates it into a stable 64-bit account id --
## exactly the shape of GetAuthSessionTicket / BeginAuthSession / SteamID64.
##
## The account id is the only identity anything downstream sees. Nothing stores
## a ticket, and nothing outside a provider interprets one.

## Reserved: never a valid account.
const NO_ACCOUNT := 0


## Client side: a ticket to present at handshake.
@abstract func get_ticket() -> PackedByteArray


## Server side: validate a ticket and return the account it proves, or
## NO_ACCOUNT to reject the connection.
@abstract func validate(ticket: PackedByteArray) -> int


## Human-readable, for logs and for the connect screen.
@abstract func provider_name() -> String