use std::{sync::Arc, time::Duration};

use robotnik::{event::Event, event_manager::EventManager};
use rstest::rstest;
use tokio::{
    io::{AsyncBufReadExt, BufReader},
    net::UnixStream,
    time::timeout,
};

const TEST_SOCKET_BASE: &str = "/tmp/robotnik_test";

/// Helper to create unique socket paths for parallel tests
fn test_socket_path(name: &str) -> String {
    format!("{}_{}_{}", TEST_SOCKET_BASE, name, std::process::id())
}

/// Helper to read one JSON event from a stream
async fn read_event(
    reader: &mut BufReader<UnixStream>,
) -> Result<Event, Box<dyn std::error::Error>> {
    let mut line = String::new();
    reader.read_line(&mut line).await?;
    let event: Event = serde_json::from_str(&line)?;
    Ok(event)
}

/// Helper to read all available events with a timeout
async fn read_events_with_timeout(
    reader: &mut BufReader<UnixStream>,
    max_count: usize,
    timeout_ms: u64,
) -> Vec<String> {
    let mut events = Vec::new();
    for _ in 0..max_count {
        let mut line = String::new();
        match timeout(
            Duration::from_millis(timeout_ms),
            reader.read_line(&mut line),
        )
        .await
        {
            Ok(Ok(0)) => break, // EOF
            Ok(Ok(_)) => events.push(line),
            Ok(Err(_)) => break, // Read error
            Err(_) => break,     // Timeout
        }
    }
    events
}

#[tokio::test]
async fn test_client_connects_and_receives_event() {
    let socket_path = test_socket_path("basic_connect");
    let manager = Arc::new(EventManager::new().unwrap());

    // Start the listener
    let listener_manager = Arc::clone(&manager);
    let socket_path_clone = socket_path.clone();
    tokio::spawn(async move {
        listener_manager.start_listening(socket_path_clone).await;
    });

    // Give the listener time to start
    tokio::time::sleep(Duration::from_millis(50)).await;

    // Broadcast an event
    let event = Event::new("test message");
    manager.broadcast(&event).await.unwrap();

    // Connect as a client
    let stream = UnixStream::connect(&socket_path).await.unwrap();
    let mut reader = BufReader::new(stream);

    // Read the event
    let mut line = String::new();
    reader.read_line(&mut line).await.unwrap();

    assert!(line.contains("test message"));
    assert!(line.ends_with('\n'));

    // Cleanup
    let _ = std::fs::remove_file(&socket_path);
}

#[tokio::test]
async fn test_client_receives_event_history() {
    let socket_path = test_socket_path("event_history");
    let manager = Arc::new(EventManager::new().unwrap());

    // Broadcast events BEFORE starting the listener
    for i in 0..5 {
        let event = Event::new(format!("historical event {}", i));
        manager.broadcast(&event).await.unwrap();
    }

    // Start the listener
    let listener_manager = Arc::clone(&manager);
    let socket_path_clone = socket_path.clone();
    tokio::spawn(async move {
        listener_manager.start_listening(socket_path_clone).await;
    });

    tokio::time::sleep(Duration::from_millis(50)).await;

    // Connect as a client
    let stream = UnixStream::connect(&socket_path).await.unwrap();
    let mut reader = BufReader::new(stream);

    // Should receive all 5 historical events
    let events = read_events_with_timeout(&mut reader, 5, 100).await;

    assert_eq!(events.len(), 5);
    assert!(events[0].contains("historical event 0"));
    assert!(events[4].contains("historical event 4"));

    // Cleanup
    let _ = std::fs::remove_file(&socket_path);
}

#[tokio::test]
async fn test_multiple_clients_receive_same_events() {
    let socket_path = test_socket_path("multiple_clients");
    let manager = Arc::new(EventManager::new().unwrap());

    // Start the listener
    let listener_manager = Arc::clone(&manager);
    let socket_path_clone = socket_path.clone();
    tokio::spawn(async move {
        listener_manager.start_listening(socket_path_clone).await;
    });

    tokio::time::sleep(Duration::from_millis(50)).await;

    // Connect 3 clients
    let stream1 = UnixStream::connect(&socket_path).await.unwrap();
    let stream2 = UnixStream::connect(&socket_path).await.unwrap();
    let stream3 = UnixStream::connect(&socket_path).await.unwrap();

    let mut reader1 = BufReader::new(stream1);
    let mut reader2 = BufReader::new(stream2);
    let mut reader3 = BufReader::new(stream3);

    // Broadcast a new event
    let event = Event::new("broadcast to all");
    manager.broadcast(&event).await.unwrap();

    // All clients should receive the event
    let mut line1 = String::new();
    let mut line2 = String::new();
    let mut line3 = String::new();

    timeout(Duration::from_millis(100), reader1.read_line(&mut line1))
        .await
        .unwrap()
        .unwrap();
    timeout(Duration::from_millis(100), reader2.read_line(&mut line2))
        .await
        .unwrap()
        .unwrap();
    timeout(Duration::from_millis(100), reader3.read_line(&mut line3))
        .await
        .unwrap()
        .unwrap();

    assert!(line1.contains("broadcast to all"));
    assert!(line2.contains("broadcast to all"));
    assert!(line3.contains("broadcast to all"));

    // Cleanup
    let _ = std::fs::remove_file(&socket_path);
}

#[tokio::test]
async fn test_late_joiner_receives_full_history() {
    let socket_path = test_socket_path("late_joiner");
    let manager = Arc::new(EventManager::new().unwrap());

    // Start the listener
    let listener_manager = Arc::clone(&manager);
    let socket_path_clone = socket_path.clone();
    tokio::spawn(async move {
        listener_manager.start_listening(socket_path_clone).await;
    });

    tokio::time::sleep(Duration::from_millis(50)).await;

    // First client connects
    let stream1 = UnixStream::connect(&socket_path).await.unwrap();
    let mut reader1 = BufReader::new(stream1);

    // Broadcast several events
    for i in 0..10 {
        let event = Event::new(format!("event {}", i));
        manager.broadcast(&event).await.unwrap();
    }

    // Consume events from first client
    let _ = read_events_with_timeout(&mut reader1, 10, 100).await;

    // Late joiner connects
    let stream2 = UnixStream::connect(&socket_path).await.unwrap();
    let mut reader2 = BufReader::new(stream2);

    // Late joiner should receive all 10 events from history
    let events = read_events_with_timeout(&mut reader2, 10, 100).await;

    assert_eq!(events.len(), 10);
    assert!(events[0].contains("event 0"));
    assert!(events[9].contains("event 9"));

    // Cleanup
    let _ = std::fs::remove_file(&socket_path);
}

#[tokio::test]
async fn test_client_receives_events_in_order() {
    let socket_path = test_socket_path("event_order");
    let manager = Arc::new(EventManager::new().unwrap());

    // Start the listener
    let listener_manager = Arc::clone(&manager);
    let socket_path_clone = socket_path.clone();
    tokio::spawn(async move {
        listener_manager.start_listening(socket_path_clone).await;
    });

    tokio::time::sleep(Duration::from_millis(50)).await;

    // Connect client
    let stream = UnixStream::connect(&socket_path).await.unwrap();
    let mut reader = BufReader::new(stream);

    // Broadcast events rapidly
    let count = 50;
    for i in 0..count {
        let event = Event::new(format!("sequence {}", i));
        manager.broadcast(&event).await.unwrap();
    }

    // Read all events
    let events = read_events_with_timeout(&mut reader, count, 500).await;

    assert_eq!(events.len(), count);

    // Verify order
    for (i, event) in events.iter().enumerate() {
        assert!(
            event.contains(&format!("sequence {}", i)),
            "Event {} out of order: {}",
            i,
            event
        );
    }

    // Cleanup
    let _ = std::fs::remove_file(&socket_path);
}

#[tokio::test]
async fn test_concurrent_broadcasts_during_client_connections() {
    let socket_path = test_socket_path("concurrent_ops");
    let manager = Arc::new(EventManager::new().unwrap());

    // Start the listener
    let listener_manager = Arc::clone(&manager);
    let socket_path_clone = socket_path.clone();
    tokio::spawn(async move {
        listener_manager.start_listening(socket_path_clone).await;
    });

    tokio::time::sleep(Duration::from_millis(50)).await;

    // Connect client 1 BEFORE any broadcasts
    let stream1 = UnixStream::connect(&socket_path).await.unwrap();
    let mut reader1 = BufReader::new(stream1);

    // Spawn a task that continuously broadcasts
    let broadcast_manager = Arc::clone(&manager);
    let broadcast_handle = tokio::spawn(async move {
        for i in 0..100 {
            let event = Event::new(format!("concurrent event {}", i));
            broadcast_manager.broadcast(&event).await.unwrap();
            tokio::time::sleep(Duration::from_millis(5)).await;
        }
    });

    // While broadcasting, connect more clients at different times
    tokio::time::sleep(Duration::from_millis(100)).await;
    let stream2 = UnixStream::connect(&socket_path).await.unwrap();
    let mut reader2 = BufReader::new(stream2);

    tokio::time::sleep(Duration::from_millis(150)).await;
    let stream3 = UnixStream::connect(&socket_path).await.unwrap();
    let mut reader3 = BufReader::new(stream3);

    // Wait for broadcasts to complete
    broadcast_handle.await.unwrap();

    // All clients should have received events
    let events1 = read_events_with_timeout(&mut reader1, 100, 200).await;
    let events2 = read_events_with_timeout(&mut reader2, 100, 200).await;
    let events3 = read_events_with_timeout(&mut reader3, 100, 200).await;

    // Client 1 connected first (before any broadcasts), should get all 100
    assert_eq!(events1.len(), 100);

    // Client 2 connected after ~20 events were broadcast
    // Gets ~20 from history + ~80 live = 100
    assert_eq!(events2.len(), 100);

    // Client 3 connected after ~50 events were broadcast
    // Gets ~50 from history + ~50 live = 100
    assert_eq!(events3.len(), 100);

    // Verify they all received events in order
    assert!(events1[0].contains("concurrent event 0"));
    assert!(events2[0].contains("concurrent event 0"));
    assert!(events3[0].contains("concurrent event 0"));

    // Cleanup
    let _ = std::fs::remove_file(&socket_path);
}

#[tokio::test]
async fn test_buffer_overflow_affects_new_clients() {
    let socket_path = test_socket_path("buffer_overflow");
    let manager = Arc::new(EventManager::new().unwrap());

    // Broadcast more than buffer max (1000)
    for i in 0..1100 {
        let event = Event::new(format!("overflow event {}", i));
        manager.broadcast(&event).await.unwrap();
    }

    // Start the listener
    let listener_manager = Arc::clone(&manager);
    let socket_path_clone = socket_path.clone();
    tokio::spawn(async move {
        listener_manager.start_listening(socket_path_clone).await;
    });

    tokio::time::sleep(Duration::from_millis(50)).await;

    // New client connects
    let stream = UnixStream::connect(&socket_path).await.unwrap();
    let mut reader = BufReader::new(stream);

    // Should receive exactly 1000 events (buffer max)
    let events = read_events_with_timeout(&mut reader, 1100, 500).await;

    assert_eq!(events.len(), 1000);

    // First event should be 100 (oldest 100 were evicted)
    assert!(events[0].contains("overflow event 100"));

    // Last event should be 1099
    assert!(events[999].contains("overflow event 1099"));

    // Cleanup
    let _ = std::fs::remove_file(&socket_path);
}

#[rstest]
#[case(10, 1)]
#[case(50, 5)]
#[tokio::test]
async fn test_client_count_scaling(#[case] num_clients: usize, #[case] events_per_client: usize) {
    let socket_path = test_socket_path(&format!("scaling_{}_{}", num_clients, events_per_client));
    let manager = Arc::new(EventManager::new().unwrap());

    // Start the listener
    let listener_manager = Arc::clone(&manager);
    let socket_path_clone = socket_path.clone();
    tokio::spawn(async move {
        listener_manager.start_listening(socket_path_clone).await;
    });

    tokio::time::sleep(Duration::from_millis(50)).await;

    // Connect many clients
    let mut readers = Vec::new();
    for _ in 0..num_clients {
        let stream = UnixStream::connect(&socket_path).await.unwrap();
        readers.push(BufReader::new(stream));
    }

    // Broadcast events
    for i in 0..events_per_client {
        let event = Event::new(format!("scale event {}", i));
        manager.broadcast(&event).await.unwrap();
    }

    // Verify all clients received all events
    for reader in &mut readers {
        let events = read_events_with_timeout(reader, events_per_client, 200).await;
        assert_eq!(events.len(), events_per_client);
    }

    // Cleanup
    let _ = std::fs::remove_file(&socket_path);
}

#[tokio::test]
async fn test_client_disconnect_doesnt_affect_others() {
    let socket_path = test_socket_path("disconnect");
    let manager = Arc::new(EventManager::new().unwrap());

    // Start the listener
    let listener_manager = Arc::clone(&manager);
    let socket_path_clone = socket_path.clone();
    tokio::spawn(async move {
        listener_manager.start_listening(socket_path_clone).await;
    });

    tokio::time::sleep(Duration::from_millis(50)).await;

    // Connect 3 clients
    let stream1 = UnixStream::connect(&socket_path).await.unwrap();
    let stream2 = UnixStream::connect(&socket_path).await.unwrap();
    let stream3 = UnixStream::connect(&socket_path).await.unwrap();

    let mut reader1 = BufReader::new(stream1);
    let mut reader2 = BufReader::new(stream2);
    let mut reader3 = BufReader::new(stream3);

    // Broadcast initial event
    manager
        .broadcast(&Event::new("before disconnect"))
        .await
        .unwrap();

    // All receive it
    let _ = read_events_with_timeout(&mut reader1, 1, 100).await;
    let _ = read_events_with_timeout(&mut reader2, 1, 100).await;
    let _ = read_events_with_timeout(&mut reader3, 1, 100).await;

    // Drop client 2 (simulates disconnect)
    drop(reader2);

    // Broadcast another event
    manager
        .broadcast(&Event::new("after disconnect"))
        .await
        .unwrap();

    // Clients 1 and 3 should still receive it
    let events1 = read_events_with_timeout(&mut reader1, 1, 100).await;
    let events3 = read_events_with_timeout(&mut reader3, 1, 100).await;

    assert_eq!(events1.len(), 1);
    assert_eq!(events3.len(), 1);
    assert!(events1[0].contains("after disconnect"));
    assert!(events3[0].contains("after disconnect"));

    // Cleanup
    let _ = std::fs::remove_file(&socket_path);
}

#[tokio::test]
async fn test_json_deserialization_of_received_events() {
    let socket_path = test_socket_path("json_deser");
    let manager = Arc::new(EventManager::new().unwrap());

    // Start the listener
    let listener_manager = Arc::clone(&manager);
    let socket_path_clone = socket_path.clone();
    tokio::spawn(async move {
        listener_manager.start_listening(socket_path_clone).await;
    });

    tokio::time::sleep(Duration::from_millis(50)).await;

    // Broadcast an event with special characters
    let test_message = "special chars: @#$% newline\\n tab\\t quotes \"test\"";
    manager.broadcast(&Event::new(test_message)).await.unwrap();

    // Connect and deserialize
    let stream = UnixStream::connect(&socket_path).await.unwrap();
    let mut reader = BufReader::new(stream);

    let mut line = String::new();
    reader.read_line(&mut line).await.unwrap();

    // Should be valid JSON
    let parsed: serde_json::Value = serde_json::from_str(&line.trim()).unwrap();

    assert_eq!(parsed["message"], test_message);

    // Cleanup
    let _ = std::fs::remove_file(&socket_path);
}