codlet-core 0.14.4

//! Form-token storage trait (RFC-007).

use std::future::Future;

use crate::hashing::{KeyVersion, LookupKey};
use crate::state::TokenConsumeOutcome;

use super::error::StoreError;

/// The subject binding for a form token (RFC-007 §13.3).
///
/// Explicit variants prevent the "empty string for anonymous" anti-pattern
/// identified in RFC-007 §13.3. Bindings are persisted as part of the token
/// record and checked on consume.
#[derive(Debug, Clone, PartialEq, Eq)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
pub enum TokenSubject {
    /// Token issued before authentication (e.g. a join form).
    Anonymous,
    /// Token issued for an authenticated subject.
    Authenticated(crate::secret::SubjectId),
    /// Token bound to a transient flow ID (e.g. a join ticket).
    Flow(crate::secret::CodeId),
}

impl TokenSubject {
    /// A stable string representation persisted in the store. This is not a
    /// security boundary on its own; the store's consume WHERE clause enforces
    /// the binding.
    #[must_use]
    pub fn as_binding_str(&self) -> String {
        match self {
            TokenSubject::Anonymous => "anon".to_string(),
            TokenSubject::Authenticated(s) => format!("auth:{}", s.as_str()),
            TokenSubject::Flow(f) => format!("flow:{}", f.as_str()),
        }
    }
}

/// A consumed token record with an optional replay reference.
#[derive(Debug, Clone)]
pub struct ConsumedTokenRecord {
    /// Whether the token has been consumed.
    pub consumed: bool,
    /// Optional result reference for idempotency replay (RFC-007 §4,
    /// `set_result`). `None` if the result was not yet stored.
    pub result_ref: Option<String>,
    /// Whether the binding checked in the consume WHERE clause matched.
    pub binding_ok: bool,
}

/// Parameters for inserting a new form token.
pub struct FormTokenRecord {
    /// Domain-separated HMAC of the token secret.
    pub lookup_key: LookupKey,
    /// Key version that produced `lookup_key`.
    pub key_version: KeyVersion,
    /// Subject binding (never an empty string).
    pub subject: TokenSubject,
    /// Purpose label, stable across the token's lifetime.
    pub purpose: String,
    /// Optional bound resource (HMAC of a domain object, not plaintext).
    pub bound_resource: Option<String>,
    /// Issuance time as Unix seconds (UTC).
    pub issued_at: u64,
    /// Expiry as Unix seconds (UTC).
    pub expires_at: u64,
}

/// Form-token storage (RFC-007).
///
/// The consume operation must be atomic: a conditional UPDATE sets `consumed_at`
/// only when the token is unconsumed, unexpired, and bindings match. The
/// affected-row count drives [`TokenConsumeOutcome`] via
/// [`crate::state::classify_token_consume`].
pub trait FormTokenStore {
    /// Insert a new form token record.
    fn insert_form_token(
        &self,
        record: FormTokenRecord,
    ) -> impl Future<Output = Result<(), StoreError>>;

    /// Attempt to atomically consume a form token.
    ///
    /// The adapter must:
    /// 1. Run the conditional UPDATE (sets `consumed_at`).
    /// 2. If `changed == 0`, run a follow-up SELECT to classify why.
    /// 3. Call [`crate::state::classify_token_consume`] with the results.
    /// 4. Return the outcome plus any stored `result_ref` for replays.
    fn consume_form_token(
        &self,
        lookup_key: &LookupKey,
        subject: &TokenSubject,
        purpose: &str,
        bound_resource: Option<&str>,
        now: u64,
    ) -> impl Future<Output = Result<(TokenConsumeOutcome, Option<String>), StoreError>>;

    /// Store a result reference on a consumed token for idempotency replay.
    fn set_token_result(
        &self,
        lookup_key: &LookupKey,
        result_ref: &str,
    ) -> impl Future<Output = Result<(), StoreError>>;
}