//! Tests for dropped announcer scenarios - critical edge cases
//!
//! These tests verify graceful behavior when the announcer is dropped
//! without announcing, ensuring no deadlocks or panics occur.

use announcement::Announcement;

use announcement::ListenError;
use std::sync::atomic::{AtomicUsize, Ordering};
use std::sync::Arc;
use std::thread;
use std::time::Duration;

/// Test: Announcer dropped without announcing, listeners wait (verify timeout needed)
///
/// Verifies: Announcer dropped without announcing, listeners wait (timeout needed)
/// Category: drop
#[test]
fn test_announcer_dropped_listeners_wait() {
    let (announcer, announcement) = Announcement::<i32>::new();
    let listener = announcement.listener();

    // Drop the announcer without announcing
    drop(announcer);

    // try_listen should return None
    assert_eq!(listener.try_listen(), None);

    // is_announced should be false
    assert!(!announcement.is_announced());
}

/// Test: Announcer dropped, then try_listen returns None as expected
///
/// Verifies: Announcer dropped, then try_listen returns None as expected
/// Category: drop
#[test]
fn test_announcer_dropped_try_listen_none() {
    let (announcer, announcement) = Announcement::<String>::new();

    // Create multiple listeners
    let listener1 = announcement.listener();
    let listener2 = announcement.listener();
    let listener3 = announcement.listener();

    // Drop announcer
    drop(announcer);

    // All try_listen calls should return None
    assert_eq!(listener1.try_listen(), None);
    assert_eq!(listener2.try_listen(), None);
    assert_eq!(listener3.try_listen(), None);

    // Even new listeners created after drop should get None
    let listener4 = announcement.listener();
    assert_eq!(listener4.try_listen(), None);
}

/// Test: Multiple listeners waiting when announcer dropped
///
/// Verifies: Multiple listeners waiting when announcer dropped
/// Category: drop
#[test]
fn test_multiple_listeners_announcer_dropped() {
    let (announcer, announcement) = Announcement::<Vec<u8>>::new();

    // Create many listeners
    let mut listeners = Vec::new();
    for _ in 0..100 {
        listeners.push(announcement.listener());
    }

    // Drop announcer
    drop(announcer);

    // All listeners should get None
    for listener in &listeners {
        assert_eq!(listener.try_listen(), None);
    }
}

/// Test: Drop test: no deadlock timeout blocking announcer dropped
///
/// Verifies: no deadlock timeout blocking announcer dropped
/// Category: drop
#[cfg(feature = "std")]
#[test]
fn test_no_deadlock_timeout_blocking_announcer_dropped() {
    let (announcer, announcement) = Announcement::<i32>::new();
    let listener = announcement.listener();

    // Drop announcer in another thread
    thread::spawn(move || {
        thread::sleep(Duration::from_millis(10));
        drop(announcer); // Sets closed flag and notifies listeners
    });

    // With closed detection, this returns Closed, not Timeout
    let result = listener.listen_timeout_blocking(Duration::from_millis(100));
    assert_eq!(result, Err(ListenError::Closed));
    assert!(announcement.is_closed());
}

/// Test: Verify graceful behavior, no panics when announcer dropped
///
/// Verifies: graceful behavior, no panics when announcer dropped
/// Category: drop
#[test]
fn test_no_panic_announcer_dropped() {
    let result = std::panic::catch_unwind(|| {
        let (announcer, announcement) = Announcement::<i32>::new();
        let listener1 = announcement.listener();
        let listener2 = announcement.listener();

        drop(announcer);

        // These should not panic
        let _ = listener1.try_listen();
        let _ = listener2.try_listen();
        let _ = announcement.is_announced();
        let _ = announcement.listener();
    });

    assert!(result.is_ok(), "Should not panic when announcer is dropped");
}

/// Test: Document behavior - announcer dropped means value never arrives
///
/// Verifies: Document behavior - announcer dropped means value never arrives
/// Category: drop
#[test]
fn test_document_dropped_announcer_behavior() {
    // This test documents the expected behavior when announcer is dropped

    let (announcer, announcement) = Announcement::<String>::new();
    let listener = announcement.listener();

    // When announcer is dropped without announcing:
    drop(announcer);

    // 1. try_listen returns None
    assert_eq!(listener.try_listen(), None);

    // 2. is_announced returns false
    assert!(!announcement.is_announced());

    // 3. New listeners also get None
    let new_listener = announcement.listener();
    assert_eq!(new_listener.try_listen(), None);

    // 4. The value will NEVER arrive (no way to announce after announcer is dropped)
}

/// Test: Announcer dropped in spawned thread
///
/// Verifies: Announcer dropped in spawned thread
/// Category: drop
#[test]
fn test_announcer_dropped_in_thread() {
    let (announcer, announcement) = Announcement::<i32>::new();
    let listener = announcement.listener();

    thread::spawn(move || {
        // Announcer dropped when thread exits
        let _ = announcer;
    })
    .join()
    .unwrap();

    assert_eq!(listener.try_listen(), None);
}

/// Test: Race between announce and drop
///
/// Verifies: Race between announce and drop
/// Category: drop
#[test]
fn test_announcer_dropped_arc_value() {
    let (announcer, announcement) = Announcement::<Arc<Vec<String>>>::new();
    let listener = announcement.listener();

    // Create an Arc value that would have been announced
    let _would_be_value = Arc::new(vec!["test".to_string()]);

    // Drop announcer instead of announcing
    drop(announcer);

    assert_eq!(listener.try_listen(), None);
}

/// Test: Many announcers dropped in parallel
///
/// Verifies: Many announcers dropped in parallel
/// Category: drop
#[test]
fn test_many_announcers_dropped_parallel() {
    let mut handles = vec![];

    for _ in 0..100 {
        handles.push(thread::spawn(|| {
            let (announcer, announcement) = Announcement::<i32>::new();
            let listener = announcement.listener();

            // Drop announcer
            drop(announcer);

            // Verify listener gets None
            assert_eq!(listener.try_listen(), None);
        }));
    }

    for handle in handles {
        handle.join().unwrap();
    }
}

/// Test: Announcer dropped after listeners created in multiple threads
///
/// Verifies: Announcer dropped after listeners created in multiple threads
/// Category: drop
#[test]
fn test_announcer_dropped_multi_thread_listeners() {
    let (announcer, announcement) = Announcement::<String>::new();
    let mut handles = vec![];

    // Create listeners in multiple threads
    for _ in 0..10 {
        let ann = announcement.clone();
        handles.push(thread::spawn(move || {
            let listener = ann.listener();
            thread::sleep(Duration::from_millis(50));
            listener.try_listen()
        }));
    }

    // Drop announcer after a short delay
    thread::sleep(Duration::from_millis(10));
    drop(announcer);

    // All threads should get None
    for handle in handles {
        let result = handle.join().unwrap();
        assert_eq!(result, None);
    }
}

/// Test: Memory is properly freed when announcer dropped
///
/// Verifies: Memory is properly freed when announcer dropped
/// Category: drop
#[test]
fn test_memory_freed_announcer_dropped() {
    static DROP_COUNT: AtomicUsize = AtomicUsize::new(0);

    #[derive(Clone)]
    struct MemoryTracker {
        _data: Vec<u8>,
    }

    impl Drop for MemoryTracker {
        /// Test: Drop test: drop
        ///
        /// Verifies: Verifies drop behavior
        /// Category: drop
        fn drop(&mut self) {
            DROP_COUNT.fetch_add(1, Ordering::SeqCst);
        }
    }

    DROP_COUNT.store(0, Ordering::SeqCst);

    {
        let (announcer, announcement) = Announcement::<MemoryTracker>::new();
        let _listener = announcement.listener();

        // Would have announced this, but drop instead
        let _would_announce = MemoryTracker {
            _data: vec![0; 1024],
        };

        drop(announcer);
        // MemoryTracker never gets into the announcement
    }

    // Only the local MemoryTracker should have been dropped
    assert_eq!(DROP_COUNT.load(Ordering::SeqCst), 1);
}

/// Test: Drop test: listener blocking wait announcer already dropped
///
/// Verifies: listener blocking wait announcer already dropped
/// Category: drop
#[cfg(feature = "std")]
#[test]
fn test_listener_blocking_wait_announcer_already_dropped() {
    let (announcer, announcement) = Announcement::<i32>::new();
    let listener = announcement.listener();

    // Drop announcer first - sets closed flag
    drop(announcer);

    // With closed detection, this returns Closed immediately, not Timeout
    let result = listener.listen_timeout_blocking(Duration::from_millis(100));
    assert_eq!(result, Err(ListenError::Closed));
    assert!(announcement.is_closed());
}

/// Test: Clone chain with dropped announcer
///
/// Verifies: Clone chain with dropped announcer
/// Category: drop
#[test]
fn test_clone_chain_dropped_announcer() {
    let (announcer, announcement) = Announcement::<i32>::new();

    let ann2 = announcement.clone();
    let ann3 = ann2.clone();

    let l1 = announcement.listener();
    let l2 = ann2.listener();
    let l3 = ann3.listener();

    drop(announcer);

    assert_eq!(l1.try_listen(), None);
    assert_eq!(l2.try_listen(), None);
    assert_eq!(l3.try_listen(), None);
}

/// Test: Dropped announcer with zero-sized type
///
/// Verifies: Dropped announcer with zero-sized type
/// Category: drop
#[test]
fn test_dropped_announcer_zst() {
    let (announcer, announcement) = Announcement::<()>::new();
    let listener = announcement.listener();

    drop(announcer);

    assert_eq!(listener.try_listen(), None);
}

/// Test: Dropped announcer with large type
///
/// Verifies: Dropped announcer with large type
/// Category: drop
#[test]
fn test_dropped_announcer_large_type() {
    #[derive(Clone, Debug, PartialEq)]
    struct LargeType {
        data: [u8; 10_000],
    }

    let (announcer, announcement) = Announcement::<LargeType>::new();
    let listener = announcement.listener();

    drop(announcer);

    assert_eq!(listener.try_listen(), None);
}

/// Test: is_announced remains false forever after announcer dropped
///
/// Verifies: is_announced remains false forever after announcer dropped
/// Category: drop
#[test]
fn test_is_announced_false_forever() {
    let (announcer, announcement) = Announcement::<i32>::new();

    drop(announcer);

    // Check multiple times - should always be false
    for _ in 0..1000 {
        assert!(!announcement.is_announced());
    }

    // Even after creating new listeners
    let _l1 = announcement.listener();
    assert!(!announcement.is_announced());

    let _l2 = announcement.listener();
    assert!(!announcement.is_announced());
}

/// Test: Stress test - rapid announcer drops
///
/// Verifies: Stress test - rapid announcer drops
/// Category: drop
#[test]
fn test_stress_rapid_announcer_drops() {
    for _ in 0..10_000 {
        let (announcer, announcement) = Announcement::<i32>::new();
        let _listener = announcement.listener();
        drop(announcer);
    }
}

/// Test: Announcer dropped with Option type
///
/// Verifies: Announcer dropped with Option type
/// Category: drop
#[test]
fn test_dropped_announcer_option() {
    let (announcer, announcement) = Announcement::<Option<String>>::new();
    let listener = announcement.listener();

    drop(announcer);

    assert_eq!(listener.try_listen(), None);
    // Note: try_listen returns None (no value), not Some(None)
}

/// Test: Announcer dropped with Result type
///
/// Verifies: Announcer dropped with Result type
/// Category: drop
#[test]
fn test_dropped_announcer_result() {
    let (announcer, announcement) = Announcement::<Result<i32, String>>::new();
    let listener = announcement.listener();

    drop(announcer);

    assert_eq!(listener.try_listen(), None);
}

/// Test: Drop test: async listen announcer dropped
///
/// Verifies: async listen announcer dropped
/// Category: drop

#[tokio::test]
async fn test_async_listen_announcer_dropped() {
    let (announcer, announcement) = Announcement::<i32>::new();
    let listener = announcement.listener();

    // Drop announcer - this sets closed flag and notifies listeners
    drop(announcer);

    // With closed detection, listen() returns Closed immediately (with timeout to prevent hanging in mutation tests)
    let result = tokio::time::timeout(Duration::from_millis(100), listener.listen())
        .await
        .expect("listen should not timeout when announcer is dropped");
    assert_eq!(result, Err(ListenError::Closed));

    // Verify closed state
    assert!(announcement.is_closed());
}

/// Test: Verify announcer can't be used after drop (compile-time safety)
///
/// Verifies: announcer can't be used after drop (compile-time safety)
/// Category: drop
#[test]
fn test_compile_time_safety_announcer_consumed() {
    let (announcer, announcement) = Announcement::<i32>::new();
    let _listener = announcement.listener();

    // This consumes the announcer
    drop(announcer);

    // The following would not compile:
    // announcer.announce(42).unwrap(); // Error: announcer was moved

    // This is enforced at compile time by Rust's ownership system
    assert!(!announcement.is_announced());
}

/// Test: Complex scenario with conditionally dropped announcer
///
/// Verifies: Complex scenario with conditionally dropped announcer
/// Category: drop
#[test]
fn test_conditional_announcer_drop() {
    fn maybe_announce(should_drop: bool) -> (Announcement<i32>, Option<i32>) {
        let (announcer, announcement) = Announcement::new();
        let listener = announcement.listener();

        if should_drop {
            drop(announcer);
            (announcement, listener.try_listen())
        } else {
            announcer.announce(42).unwrap();
            (announcement, listener.try_listen())
        }
    }

    // Test both paths
    let (_ann1, result1) = maybe_announce(true);
    assert_eq!(result1, None);

    let (_ann2, result2) = maybe_announce(false);
    assert_eq!(result2, Some(42));
}

/// Test: Announcer dropped in destructor of another type
///
/// Verifies: Announcer dropped in destructor of another type
/// Category: drop
#[test]
fn test_announcer_dropped_in_destructor() {
    struct AnnouncerHolder<T> {
        announcer: Option<announcement::Announcer<T>>,
    }

    impl<T> Drop for AnnouncerHolder<T> {
        fn drop(&mut self) {
            // Announcer dropped here without announcing
            self.announcer.take();
        }
    }

    let (announcer, announcement) = Announcement::<String>::new();
    let listener = announcement.listener();

    {
        let _holder = AnnouncerHolder {
            announcer: Some(announcer),
        };
        // Holder dropped here, taking announcer with it
    }

    assert_eq!(listener.try_listen(), None);
}

/// Test: Thread panic while holding announcer
///
/// Verifies: Thread panic while holding announcer
/// Category: drop
#[test]
fn test_thread_panic_with_announcer() {
    let (announcer, announcement) = Announcement::<i32>::new();
    let listener = announcement.listener();

    let handle = thread::spawn(move || {
        let _announcer = announcer;
        panic!("Intentional panic while holding announcer");
    });

    // Thread panicked, dropping announcer
    assert!(handle.join().is_err());

    assert_eq!(listener.try_listen(), None);
}

/// Test: Announcer dropped with recursive structure
///
/// Verifies: Announcer dropped with recursive structure
/// Category: drop
#[test]
fn test_dropped_announcer_recursive() {
    #[derive(Clone, Debug, PartialEq)]
    struct Node {
        value: i32,
        next: Option<Box<Node>>,
    }

    let (announcer, announcement) = Announcement::<Node>::new();
    let listener = announcement.listener();

    drop(announcer);

    assert_eq!(listener.try_listen(), None);
}

/// Test: Drop test: document blocking behavior
///
/// Verifies: document blocking behavior
/// Category: drop
#[cfg(feature = "std")]
#[test]
fn test_document_blocking_behavior() {
    let (announcer, announcement) = Announcement::<i32>::new();
    let listener = announcement.listener();

    thread::spawn(move || {
        thread::sleep(Duration::from_millis(10));
        drop(announcer); // Drop instead of announce
    });

    // This will timeout because announcer was dropped
    let result = listener.listen_timeout_blocking(Duration::from_millis(100));

    match result {
        Err(ListenError::Timeout) => {
            // Expected: timeout because announcer was dropped
        }
        Err(ListenError::Closed) => {
            // Also acceptable: closed because announcer was dropped
        }
        Ok(_) => panic!("Should not receive value when announcer is dropped"),
    }
}

/// Test: Multiple announcement channels with some dropped announcers
///
/// Verifies: Multiple announcement channels with some dropped announcers
/// Category: drop
#[test]
fn test_multiple_channels_some_dropped() {
    let (a1, ann1) = Announcement::<i32>::new();
    let (a2, ann2) = Announcement::<i32>::new();
    let (a3, ann3) = Announcement::<i32>::new();

    let l1 = ann1.listener();
    let l2 = ann2.listener();
    let l3 = ann3.listener();

    // Announce on first, drop others
    a1.announce(42).unwrap();
    drop(a2);
    drop(a3);

    assert_eq!(l1.try_listen(), Some(42));
    assert_eq!(l2.try_listen(), None);
    assert_eq!(l3.try_listen(), None);
}