//! Token revocation (RFC 7009) with family cascade.
//!
//! `POST /revoke` authenticates the caller (see [`super::client_auth`]),
//! accepts an optional `token_type_hint`, and invalidates the presented
//! token. Revoking a refresh token cascades to its grant family, so every
//! token minted from the same authorization grant dies with it.
//!
//! # Ownership and non-oracle semantics
//!
//! A client may revoke only a token it owns. The lookup is performed before
//! the ownership decision, and a token that is unknown, already gone, or
//! **owned by another client** collapses to the same `200` no-op response —
//! the endpoint never reveals whether a token exists and never cross-revokes.
//!
//! Well-formed requests always answer `200 OK` (RFC 7009 §2.2): unknown and
//! invalid tokens are not an error. Client authentication failure is the only
//! failure for an otherwise valid request (`invalid_client`); a token-type
//! hint naming an unsupported type is `unsupported_token_type`.

use std::collections::HashMap;

use axum::{
  Extension, Form, Json,
  extract::State,
  http::{HeaderMap, StatusCode, header},
  response::{IntoResponse, Response},
};
use secrecy::SecretString;
use serde::Serialize;
use sqlx::PgPool;
use time::OffsetDateTime;

use super::{
  client_auth::{AuthContext, AuthStores, ClientAuthRequest, authenticate_client},
  token::TokenService,
};
use crate::{
  error::AppError,
  jose::jwt_access::{JwtAccessSigner, is_jwt_shape, jti_hash},
  middleware::{
    audit::AuditEvent,
    request_id::{REQUEST_ID_HEADER, RequestId},
  },
  state::{AppState, RedisConn},
  store::{Store, StoreError, durability_barrier},
  tls::PeerCertificates,
};

/// Supported `token_type_hint` value for access tokens (RFC 7009 §2.1).
const HINT_ACCESS: &str = "access_token";

/// Supported `token_type_hint` value for refresh tokens (RFC 7009 §2.1).
const HINT_REFRESH: &str = "refresh_token";

/// Client-safe description for `unsupported_token_type`.
const UNSUPPORTED_TOKEN_TYPE: &str =
  "The authorization server does not support the revocation of the presented token type.";

/// Datastore handles needed by [`revoke_tokens`].
pub struct RevokeStores<'a> {
  /// Postgres pool for client authentication.
  pub pool: &'a PgPool,
  /// Versioned PII keys for the encrypted client lookup.
  pub keys: &'a crate::keys::KeyRing,
  /// Redis connection for the token and grant stores.
  pub conn: &'a mut RedisConn,
  /// Key layout plus retry/durability knobs.
  pub store: &'a Store,
  /// Token lookup and revocation primitives.
  pub service: &'a TokenService,
}

/// Request-scoped authentication and audit inputs for [`revoke_tokens`].
pub struct RevokeContext<'a> {
  /// Canonical token endpoint URL used as the `private_key_jwt` audience.
  pub token_endpoint: &'a str,
  /// Current time for client-secret expiry enforcement.
  pub now: OffsetDateTime,
  /// CIMD resolution settings for a registration-free fallback; `None` when
  /// `config.cimd_enabled` is off (RFC 7009 §2.1: a registration-free
  /// client revokes its own token through this same path).
  pub cimd: Option<crate::protocol::cimd::CimdSettings<'a>>,
  /// Correlating request id for the audit event, when present.
  pub request_id: Option<&'a str>,
}

/// One revocation request: the token, its optional hint, and credentials.
pub struct RevokeRequest<'a> {
  /// The token the client wants revoked (required, never empty).
  pub token: &'a str,
  /// Optional RFC 7009 `token_type_hint`.
  pub token_type_hint: Option<&'a str>,
  /// Client credentials from the `Authorization` header and the form body.
  pub auth: &'a ClientAuthRequest<'a>,
}

/// Outcome of a well-formed revocation request.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum RevokeOutcome {
  /// The caller owned the token; it (and its family for a refresh) is gone.
  Revoked,
  /// Unknown, already revoked, or owned by another client — no-op `200`.
  NoOp,
  /// The `token_type_hint` names no supported token type.
  UnsupportedHint,
}

/// The token to revoke plus the authenticated owner that must match its record.
struct OwnedToken<'a> {
  /// Client that authenticated this request.
  owner_client_id: &'a str,
  /// Presented token value.
  token: &'a str,
  /// Optional type hint (used only to reject unsupported values).
  token_type_hint: Option<&'a str>,
}

/// Authenticate the caller, then revoke the token if (and only if) the caller
/// owns it.
///
/// A completely unauthenticated request (no `Authorization` header, body
/// secret, client assertion, or `client_id`) is `401` + `WWW-Authenticate`,
/// because the endpoint is a protected resource (RFC 7009 §2.1).
///
/// `jwt_signer` carries the AS access-token signer for the JWT allowlist path
/// (built from the config by the handler only when the presented token has
/// JWT shape and the operator switch is on); `None` leaves a JWT-shaped token
/// as a silent no-op. It is never consulted on the opaque path.
///
/// # Errors
///
/// Returns `invalid_request` for a missing token, `invalid_client` for failed
/// authentication, and a masked store failure otherwise.
pub async fn revoke_tokens(
  stores: &mut RevokeStores<'_>,
  ctx: &RevokeContext<'_>,
  request: &RevokeRequest<'_>,
  jwt_signer: Option<&JwtAccessSigner>,
) -> Result<RevokeOutcome, AppError> {
  if request.token.is_empty() {
    return Err(AppError::invalid_request("token is required"));
  }
  if is_unauthenticated(request.auth) {
    return Err(AppError::invalid_client_basic());
  }
  let authenticated = {
    let mut auth_stores = AuthStores {
      pool: stores.pool,
      keys: stores.keys,
      conn: stores.conn,
      store: stores.store,
    };
    let auth_ctx = AuthContext {
      token_endpoint: ctx.token_endpoint,
      now: ctx.now,
      cimd: ctx.cimd,
    };
    authenticate_client(&mut auth_stores, &auth_ctx, request.auth).await?
  };

  let owned = OwnedToken {
    owner_client_id: &authenticated.client.client_id,
    token: request.token,
    token_type_hint: request.token_type_hint,
  };
  let outcome = revoke_owned(
    stores.conn,
    stores.store,
    stores.service,
    &owned,
    jwt_signer,
  )
  .await?;
  if matches!(outcome, RevokeOutcome::Revoked) {
    AuditEvent::TokenRevoke {
      request_id: ctx.request_id,
      client_id: &authenticated.client.client_id,
    }
    .emit();
  }
  Ok(outcome)
}

/// Whether no client credential of any style was presented.
fn is_unauthenticated(auth: &ClientAuthRequest<'_>) -> bool {
  auth.basic_header.is_none()
    && auth.body_secret.is_none()
    && auth.assertion.is_none()
    && auth.client_id.is_none()
}

/// Revoke a token owned by `owner_client_id`.
///
/// Both record slots are probed before the ownership decision so the existence
/// lookup is uniform; a foreign owner returns [`RevokeOutcome::NoOp`] without
/// touching the store. A refresh token revokes the whole grant chain; an access
/// token revokes only itself.
///
/// A JWT-shaped token (RFC 9068 §4 allowlist) misses both opaque slots by
/// construction and falls through to [`revoke_jwt_owned`]: signature plus
/// `iss` are verified, ownership is enforced from the verified `client_id`
/// (and the marker's own `client_id` field), and only then are the marker and
/// the access record/member deleted. Every miss — malformed, foreign-key,
/// expired, wrong-issuer, foreign-owner, or already revoked — collapses to
/// [`RevokeOutcome::NoOp`] (uniform HTTP 200 per RFC 7009 §2.2); a foreign
/// token is never revoked.
async fn revoke_owned(
  conn: &mut RedisConn,
  store: &Store,
  service: &TokenService,
  owned: &OwnedToken<'_>,
  jwt_signer: Option<&JwtAccessSigner>,
) -> Result<RevokeOutcome, AppError> {
  match owned.token_type_hint.filter(|hint| !hint.is_empty()) {
    None | Some(HINT_ACCESS | HINT_REFRESH) => {}
    Some(_) => return Ok(RevokeOutcome::UnsupportedHint),
  }

  let access = service.find_access(conn, store, owned.token).await?;
  let refresh = service.find_refresh(conn, store, owned.token).await?;

  if let Some(found) = access {
    if found.record.client_id != owned.owner_client_id {
      return Ok(RevokeOutcome::NoOp);
    }
    service.revoke_token(conn, store, owned.token).await?;
    return Ok(RevokeOutcome::Revoked);
  }
  if let Some(found) = refresh {
    if found.record.client_id != owned.owner_client_id {
      return Ok(RevokeOutcome::NoOp);
    }
    service
      .revoke_grant(conn, store, &found.record.grant_id)
      .await?;
    return Ok(RevokeOutcome::Revoked);
  }
  if is_jwt_shape(owned.token) {
    return revoke_jwt_owned(conn, store, owned, jwt_signer).await;
  }
  Ok(RevokeOutcome::NoOp)
}

/// Revoke a JWT access token owned by `owner_client_id` (RFC 7009 §2.1).
///
/// The token must verify under the AS signer (header `typ`/`alg`/`kid`,
/// signature, `iss`, `exp`; `expected_aud` is `None` because revocation is
/// audience-agnostic) and the verified `client_id` must equal the caller. The
/// `jwt:<jti-hash>` marker is then read: an absent marker means the token is
/// already revoked (`NoOp`), and a marker whose `client_id` names another
/// client is never touched (`NoOp`). Otherwise the marker hash, the
/// `access:jwt:<jti-hash>` record, and the grant-set member are deleted — the
/// honest equivalent of [`TokenService::revoke_token`] for the member identity
/// `jwt:<jti-hash>` (a `SREM` from the grant set plus `DEL` of the record
/// key), barriered before returning.
async fn revoke_jwt_owned(
  conn: &mut RedisConn,
  store: &Store,
  owned: &OwnedToken<'_>,
  jwt_signer: Option<&JwtAccessSigner>,
) -> Result<RevokeOutcome, AppError> {
  let signer = match jwt_signer {
    Some(signer) => signer,
    None => return Ok(RevokeOutcome::NoOp),
  };
  let verified = match signer.verify(owned.token, None) {
    Ok(verified) => verified,
    Err(_) => return Ok(RevokeOutcome::NoOp),
  };
  if verified.claims.client_id != owned.owner_client_id {
    return Ok(RevokeOutcome::NoOp);
  }
  let hash = jti_hash(&verified.claims.jti);
  let marker_key = store.jwt_marker_key(&hash);
  let fields: HashMap<String, String> = redis::cmd("HGETALL")
    .arg(&marker_key)
    .query_async(conn)
    .await
    .map_err(StoreError::Redis)?;
  if fields.is_empty() {
    return Ok(RevokeOutcome::NoOp);
  }
  if fields.get("client_id").map(String::as_str) != Some(owned.owner_client_id) {
    return Ok(RevokeOutcome::NoOp);
  }
  let member = format!("jwt:{hash}");
  let record_key = store.access_key(&member);
  let grant_id = fields.get("grant_id").cloned().unwrap_or_default();
  let set_key = store.grant_tokens_key(&grant_id);
  let _: () = redis::cmd("DEL")
    .arg(&record_key)
    .arg(&marker_key)
    .query_async(conn)
    .await
    .map_err(StoreError::Redis)?;
  if !grant_id.is_empty() {
    let _: () = redis::cmd("SREM")
      .arg(&set_key)
      .arg(&member)
      .query_async(conn)
      .await
      .map_err(StoreError::Redis)?;
  }
  durability_barrier(conn, store)
    .await
    .map_err(AppError::from)?;
  Ok(RevokeOutcome::Revoked)
}

/// Render a revocation outcome: `200 OK` with an empty body for success and
/// no-ops, `400` with `unsupported_token_type` for a rejected hint.
fn outcome_response(outcome: RevokeOutcome) -> Response {
  match outcome {
    RevokeOutcome::Revoked | RevokeOutcome::NoOp => StatusCode::OK.into_response(),
    RevokeOutcome::UnsupportedHint => (
      StatusCode::BAD_REQUEST,
      Json(ErrorBody {
        error: "unsupported_token_type",
        error_description: UNSUPPORTED_TOKEN_TYPE,
      }),
    )
      .into_response(),
  }
}

/// The JSON body for a locally-owned revocation error code.
#[derive(Debug, Serialize)]
struct ErrorBody {
  /// The wire error code.
  error: &'static str,
  /// A client-safe description.
  error_description: &'static str,
}

/// `POST /revoke` (RFC 7009 §2.1).
///
/// Credentials come from the `Authorization` header and the form body only; a
/// secret in the query string is never consulted. mTLS-registered clients
/// (RFC 8705 §2) authenticate with `client_id` plus the verified peer chain
/// injected by the TLS accept loop, exactly as the token and introspection
/// endpoints do; a missing or unregistered chain fails closed as
/// `invalid_client`. No forwarded header is ever trusted: only the in-process
/// [`PeerCertificates`] extension counts as mTLS evidence.
///
/// Certificate revocation story: client certificates are expected to be
/// short-lived, so expiry bounds exposure without any revocation list; a
/// CRL/OCSP check at authentication time is the hook point if deployments
/// later need explicit revocation (verify freshness there, fail closed on
/// outage, never cache a good verdict past the response's validity window).
/// All well-formed requests answer `200 OK`, including unknown or foreign
/// tokens.
///
/// # Errors
///
/// Returns the [`revoke_tokens`] failure: `invalid_client` for failed
/// authentication and a masked `server_error` when storage fails. A rejected
/// `token_type_hint` is rendered as `400 unsupported_token_type`.
pub async fn revoke_handler(
  State(state): State<AppState>,
  peer_certs: Option<Extension<PeerCertificates>>,
  headers: HeaderMap,
  Form(form): Form<HashMap<String, String>>,
) -> Result<Response, AppError> {
  let service = TokenService::new(&state.config.ttl, &state.keys)?;
  let auth = ClientAuthRequest {
    basic_header: headers
      .get(header::AUTHORIZATION)
      .and_then(|value| value.to_str().ok()),
    client_id: form.get("client_id").map(String::as_str),
    body_secret: form
      .get("client_secret")
      .map(|secret| SecretString::from(secret.as_str())),
    assertion_type: form.get("client_assertion_type").map(String::as_str),
    assertion: form.get("client_assertion").map(String::as_str),
    peer_certs: peer_certs.as_deref(),
  };
  let mut redis = state.redis.clone();
  let store = Store::from_config(&state.config.redis);
  let mut stores = RevokeStores {
    pool: &state.pool,
    keys: &state.keys,
    conn: &mut redis,
    store: &store,
    service: &service,
  };
  let token_endpoint = super::client_auth::token_endpoint(&state.config.issuer);
  let request_id = headers
    .get(REQUEST_ID_HEADER)
    .and_then(|value| value.to_str().ok())
    .and_then(RequestId::parse);
  let ctx = RevokeContext {
    token_endpoint: &token_endpoint,
    now: state.clock.now(),
    cimd: state
      .config
      .cimd_enabled
      .then(|| crate::protocol::cimd::CimdSettings {
        token_prefix: &state.config.redis.token_key_prefix,
        max_bytes: state.config.cimd_max_bytes,
        timeout: state.config.cimd_fetch_timeout,
        allow_localhost: state.config.allow_localhost_redirect,
      }),
    request_id: request_id.as_ref().map(RequestId::as_str),
  };
  let request = RevokeRequest {
    token: form.get("token").map(String::as_str).unwrap_or_default(),
    token_type_hint: form.get("token_type_hint").map(String::as_str),
    auth: &auth,
  };
  // The signer is built only on the JWT-shaped path: opaque revocations never
  // touch the signing config. A missing key or a disabled switch leaves a
  // JWT-shaped token as a silent no-op.
  let jwt_signer = if is_jwt_shape(request.token) && state.config.jwt_access_tokens_enabled {
    JwtAccessSigner::from_config(&state.config).ok()
  } else {
    None
  };
  let outcome = revoke_tokens(&mut stores, &ctx, &request, jwt_signer.as_ref()).await?;
  Ok(outcome_response(outcome))
}

#[cfg(test)]
mod tests;