use std::{
    sync::{
        Arc,
        atomic::{AtomicU64, Ordering},
    },
    time::Duration,
};

use litellm_cache::ExactCacheContext;
use litellm_cache_memory::InMemoryCache;
use litellm_cache_response::{
    CacheEntry, CacheKeyInput, ResponseCache, ResponseCacheConfig, ResponseCacheRequest,
    ResponseCacheService,
};
use rstest::rstest;
use serde_json::json;

#[rstest]
#[tokio::test]
async fn service_honors_per_call_expiry_and_freshness() {
    let clock = Arc::new(AtomicU64::new(0));
    let cache_clock = clock.clone();
    let cache: Arc<dyn ResponseCacheService> = Arc::new(ResponseCache::new(Arc::new(
        InMemoryCache::with_clock(Some(100), Some(Duration::from_secs(60)), move || {
            Duration::from_secs(cache_clock.load(Ordering::SeqCst))
        }),
    )));
    let request = ResponseCacheRequest {
        context: ExactCacheContext {
            ttl: Some(Duration::from_secs(5)),
        },
        ..ResponseCacheRequest::new(CacheKeyInput {
            preset: Some("entry".into()),
            ..Default::default()
        })
    };
    cache
        .store(&request, json!({"answer":7}), Duration::ZERO)
        .await
        .unwrap();
    assert_eq!(
        cache.lookup(&request, Duration::ZERO).await.unwrap(),
        Some(json!({"answer":7}))
    );
    let stale_request = ResponseCacheRequest {
        max_age: Some(Duration::from_secs(1)),
        ..request.clone()
    };
    clock.store(2, Ordering::SeqCst);
    assert_eq!(
        cache
            .lookup(&stale_request, Duration::from_secs(2))
            .await
            .unwrap(),
        None
    );
    assert!(
        cache
            .lookup(&request, Duration::from_secs(2))
            .await
            .unwrap()
            .is_some()
    );
    clock.store(6, Ordering::SeqCst);
    assert_eq!(
        cache
            .lookup(&request, Duration::from_secs(6))
            .await
            .unwrap(),
        None
    );
}

#[rstest]
#[tokio::test]
async fn entry_limit_applies_to_sync_async_and_batch_writes() {
    let storage = Arc::new(InMemoryCache::<CacheEntry>::default());
    let cache = ResponseCache::new(storage.clone()).with_config(ResponseCacheConfig {
        namespace: "service-test".into(),
        max_entry_bytes: json!({"answer":7}).to_string().len(),
    });
    let small = json!({"answer":7});
    let large = json!({"answer":"too large"});
    let request = |key: &str| {
        ResponseCacheRequest::new(CacheKeyInput {
            preset: Some(key.into()),
            ..Default::default()
        })
    };
    cache
        .store(&request("sync"), large.clone(), Duration::ZERO)
        .unwrap();
    cache
        .async_store(&request("async"), large.clone(), Duration::ZERO)
        .await
        .unwrap();
    cache
        .async_store_batch(
            vec![
                (request("batch-large"), large),
                (request("batch-small"), small.clone()),
            ],
            Duration::ZERO,
        )
        .await
        .unwrap();
    let service: Arc<dyn ResponseCacheService> = Arc::new(cache);
    service
        .store(&request("service"), small.clone(), Duration::ZERO)
        .await
        .unwrap();
    for key in ["sync", "async", "batch-large"] {
        assert!(storage.get_cache(key).unwrap().is_none());
    }
    for key in ["batch-small", "service"] {
        assert_eq!(
            service.lookup(&request(key), Duration::ZERO).await.unwrap(),
            Some(small.clone())
        );
    }
}

#[rstest]
#[case::same_scope("tenant-a", "tenant-a", true)]
#[case::different_scope("tenant-a", "tenant-b", false)]
#[case::empty_isolated_scope("", "", true)]
#[tokio::test]
async fn isolated_policy_controls_actual_entry_reuse(
    #[case] first: &str,
    #[case] second: &str,
    #[case] hit: bool,
    #[values(false, true)] override_policy: bool,
) {
    use litellm_cache_response::{CachePolicy, CacheScope, ScopedCache};
    let service = Arc::new(ResponseCache::new(Arc::new(
        InMemoryCache::<CacheEntry>::default(),
    )));
    let request = |scope| {
        ScopedCache::new(service.clone(), scope)
            .options(override_policy.then_some(CachePolicy {
                ttl: Some(Duration::from_secs(30)),
                ..CachePolicy::default()
            }))
            .request("test", "messages", json!({"prompt":"hello"}))
    };
    service
        .async_store(
            &request(CacheScope::Isolated(first.into())),
            json!({"answer":7}),
            Duration::ZERO,
        )
        .await
        .unwrap();
    assert_eq!(
        service
            .async_lookup(
                &request(CacheScope::Isolated(second.into())),
                Duration::ZERO
            )
            .await
            .unwrap(),
        hit.then(|| json!({"answer":7}))
    );
    assert_eq!(
        service
            .async_lookup(&request(CacheScope::Shared), Duration::ZERO)
            .await
            .unwrap(),
        None
    );
}

#[rstest]
#[case::valid(1, "messages", Some(7))]
#[case::unknown_version(2, "messages", None)]
#[case::another_surface(1, "responses", None)]
fn envelopes_require_a_matching_surface_and_version(
    #[case] version: u32,
    #[case] surface: &str,
    #[case] expected: Option<u32>,
) {
    let envelope: litellm_cache_response::ResponseEnvelope<u32> =
        serde_json::from_value(json!({"version":version,"surface":surface,"output":7})).unwrap();
    assert_eq!(envelope.decode("messages"), expected);
}