secrets-core 0.1.1

use std::sync::Arc;
use std::time::Duration;

use chrono::Utc;
use thiserror::Error;

use crate::engine::EngineError;
use crate::lease::{self, Lease};
use crate::router::Router;
use crate::storage::{StorageBackend, StorageError};

#[derive(Debug, Error)]
pub enum ReaperError {
    #[error("storage error: {0}")]
    Storage(#[from] StorageError),
    #[error("engine error: {0}")]
    Engine(#[from] EngineError),
}

/// Revokes one lease by asking its owning engine mount to `revoke()` it,
/// then removing the lease record. Best-effort: engine failures are
/// reported to the caller but the lease record is only deleted on success,
/// so a failed revoke is retried on the next pass rather than silently lost.
pub async fn revoke_lease(
    storage: &dyn StorageBackend,
    router: &Router,
    lease: &Lease,
) -> Result<(), ReaperError> {
    if let Some((mount, _)) = router.resolve(&lease.engine_mount) {
        mount.engine.revoke(storage, lease).await?;
    }
    lease::delete_lease(storage, lease.id).await?;
    Ok(())
}

/// Revokes every lease owned by `token_id_hash` — called when a token is
/// revoked so its dynamic credentials don't outlive it.
pub async fn revoke_leases_for_token(
    storage: &dyn StorageBackend,
    router: &Router,
    token_id_hash: &str,
) -> Result<(), ReaperError> {
    for lease in lease::list_leases(storage).await? {
        if lease.token_id_hash == token_id_hash {
            revoke_lease(storage, router, &lease).await?;
        }
    }
    Ok(())
}

/// Scans all leases once and revokes any that have expired. Returns the
/// number successfully reaped; individual failures are logged and skipped
/// (they'll be retried on the next pass).
pub async fn reap_once(storage: &dyn StorageBackend, router: &Router) -> Result<usize, ReaperError> {
    let now = Utc::now();
    let mut reaped = 0;
    for lease in lease::list_leases(storage).await? {
        if lease.expires_at <= now {
            match revoke_lease(storage, router, &lease).await {
                Ok(()) => reaped += 1,
                Err(e) => tracing::warn!(lease_id = %lease.id, error = %e, "failed to reap lease"),
            }
        }
    }
    Ok(reaped)
}

/// Spawns a background task that calls `reap_once` on a fixed interval for
/// the lifetime of the process. Single-node only: a multi-node deployment
/// would need a Postgres advisory lock here so only one instance reaps at a
/// time.
pub fn spawn_reaper(
    storage: Arc<dyn StorageBackend>,
    router: Arc<Router>,
    interval: Duration,
) -> tokio::task::JoinHandle<()> {
    tokio::spawn(async move {
        let mut ticker = tokio::time::interval(interval);
        loop {
            ticker.tick().await;
            match reap_once(storage.as_ref(), router.as_ref()).await {
                Ok(count) if count > 0 => tracing::info!(count, "reaped expired leases"),
                Ok(_) => {}
                Err(e) => tracing::warn!(error = %e, "lease reaper pass failed"),
            }
        }
    })
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::engine::{EngineResult, SecretsEngine};
    use crate::router::EngineMount;
    use crate::storage::{StorageEntry, StorageResult};
    use async_trait::async_trait;
    use std::collections::HashMap;
    use std::sync::atomic::{AtomicUsize, Ordering};
    use std::sync::Mutex;
    use uuid::Uuid;

    #[derive(Default)]
    struct MemStorage(Mutex<HashMap<String, StorageEntry>>);

    #[async_trait]
    impl StorageBackend for MemStorage {
        async fn get(&self, path: &str) -> StorageResult<Option<StorageEntry>> {
            Ok(self.0.lock().unwrap().get(path).cloned())
        }
        async fn put(&self, path: &str, entry: StorageEntry) -> StorageResult<()> {
            self.0.lock().unwrap().insert(path.to_string(), entry);
            Ok(())
        }
        async fn delete(&self, path: &str) -> StorageResult<()> {
            self.0.lock().unwrap().remove(path);
            Ok(())
        }
        async fn list(&self, prefix: &str) -> StorageResult<Vec<String>> {
            Ok(self
                .0
                .lock()
                .unwrap()
                .keys()
                .filter(|k| k.starts_with(prefix))
                .cloned()
                .collect())
        }
    }

    #[derive(Default)]
    struct FakeEngine {
        revoked: AtomicUsize,
    }

    #[async_trait]
    impl SecretsEngine for FakeEngine {
        async fn read(&self, _storage: &dyn StorageBackend, _path: &str) -> EngineResult<serde_json::Value> {
            unimplemented!()
        }
        async fn write(
            &self,
            _storage: &dyn StorageBackend,
            _path: &str,
            _data: serde_json::Value,
        ) -> EngineResult<()> {
            unimplemented!()
        }
        async fn delete(&self, _storage: &dyn StorageBackend, _path: &str) -> EngineResult<()> {
            unimplemented!()
        }
        async fn list(&self, _storage: &dyn StorageBackend, _prefix: &str) -> EngineResult<Vec<String>> {
            unimplemented!()
        }
        async fn revoke(&self, _storage: &dyn StorageBackend, _lease: &Lease) -> EngineResult<()> {
            self.revoked.fetch_add(1, Ordering::SeqCst);
            Ok(())
        }
    }

    fn lease(token_id_hash: &str, expires_at: chrono::DateTime<Utc>) -> Lease {
        Lease {
            id: Uuid::new_v4(),
            token_id_hash: token_id_hash.to_string(),
            engine_mount: "database/creds/".to_string(),
            internal_data: serde_json::json!({}),
            issued_at: Utc::now(),
            expires_at,
        }
    }

    #[tokio::test]
    async fn reap_once_revokes_only_expired_leases() {
        let storage = MemStorage::default();
        let engine: Arc<dyn SecretsEngine> = Arc::new(FakeEngine::default());
        let router = Router::new(vec![EngineMount {
            prefix: "database/creds/".to_string(),
            engine: engine.clone(),
        }]);

        let expired = lease("tok", Utc::now() - chrono::Duration::seconds(10));
        let active = lease("tok", Utc::now() + chrono::Duration::seconds(3600));
        lease::store_lease(&storage, &expired).await.unwrap();
        lease::store_lease(&storage, &active).await.unwrap();

        let reaped = reap_once(&storage, &router).await.unwrap();
        assert_eq!(reaped, 1);
        assert_eq!(lease::list_leases(&storage).await.unwrap().len(), 1);
    }

    #[tokio::test]
    async fn revoke_leases_for_token_cascades() {
        let storage = MemStorage::default();
        let engine: Arc<dyn SecretsEngine> = Arc::new(FakeEngine::default());
        let router = Router::new(vec![EngineMount {
            prefix: "database/creds/".to_string(),
            engine,
        }]);

        let mine = lease("tok-a", Utc::now() + chrono::Duration::seconds(3600));
        let theirs = lease("tok-b", Utc::now() + chrono::Duration::seconds(3600));
        lease::store_lease(&storage, &mine).await.unwrap();
        lease::store_lease(&storage, &theirs).await.unwrap();

        revoke_leases_for_token(&storage, &router, "tok-a").await.unwrap();

        let remaining = lease::list_leases(&storage).await.unwrap();
        assert_eq!(remaining.len(), 1);
        assert_eq!(remaining[0].token_id_hash, "tok-b");
    }
}