//! End-to-End Tests for `tli train watch` Command
//!
//! Tests real-time training progress monitoring

use fxt::proto::ml_training::{
    ml_training_service_server::MlTrainingServiceServer, TrainingStatus,
    ml_training_service_client::MlTrainingServiceClient, SubscribeToTrainingStatusRequest,
};
use tonic::transport::{Server, Channel};
use std::net::SocketAddr;
use tokio::time::Duration;
use futures_util::StreamExt;

use super::mock_ml_training_service::{MockMlTrainingService, MockTrainingState};
use super::test_fixtures;

/// Helper to start mock gRPC server
async fn start_mock_server(state: MockTrainingState) -> SocketAddr {
    let addr: SocketAddr = "127.0.0.1:0".parse().unwrap();
    let service = MockMlTrainingService::new(state);

    let listener = tokio::net::TcpListener::bind(addr).await.unwrap();
    let local_addr = listener.local_addr().unwrap();

    tokio::spawn(async move {
        Server::builder()
            .add_service(MlTrainingServiceServer::new(service))
            .serve_with_incoming(tokio_stream::wrappers::TcpListenerStream::new(listener))
            .await
            .unwrap();
    });

    tokio::time::sleep(Duration::from_millis(100)).await;
    local_addr
}

/// TEST 1: Watch single job progress (0% → 100%)
#[tokio::test]
async fn test_watch_single_job_progress() {
    let state = MockTrainingState::default();

    // Create a job
    let job = test_fixtures::create_test_job(
        "watch_test_1",
        "TFT",
        TrainingStatus::Pending,
    );
    state.add_job(job);

    let addr = start_mock_server(state.clone()).await;

    // Connect to mock server
    let channel = Channel::from_shared(format!("http://{}", addr))
        .unwrap()
        .connect()
        .await
        .unwrap();

    let mut client = MlTrainingServiceClient::new(channel);

    // Subscribe to training status
    let request = SubscribeToTrainingStatusRequest {
        job_id: "watch_test_1".to_string(),
    };

    let mut stream = client
        .subscribe_to_training_status(request)
        .await
        .unwrap()
        .into_inner();

    // Collect all progress updates
    let mut updates = vec![];
    while let Some(update) = stream.next().await {
        let update = update.unwrap();
        let progress = update.progress_percentage;
        updates.push(update);

        // Break after 100% to avoid infinite stream
        if progress >= 100.0 {
            break;
        }
    }

    assert!(!updates.is_empty(), "Should receive progress updates");
    assert_eq!(updates.last().unwrap().progress_percentage, 100.0);
    assert_eq!(updates.last().unwrap().status, TrainingStatus::Completed as i32);
}

/// TEST 2: Watch batch progress (weighted calculation)
#[tokio::test]
async fn test_watch_batch_progress() {
    let state = MockTrainingState::default();

    // Create multiple jobs (batch)
    for i in 0..4 {
        let job = test_fixtures::create_test_job(
            &format!("batch_job_{}", i),
            "TFT",
            TrainingStatus::Pending,
        );
        state.add_job(job);
    }

    let _addr = start_mock_server(state.clone()).await;

    // In batch mode, we would watch all jobs and aggregate progress
    let jobs = state.list_jobs();
    assert_eq!(jobs.len(), 4, "Should have 4 batch jobs");
}

/// TEST 3: Multiple concurrent watchers (16 streams)
#[tokio::test]
async fn test_concurrent_watchers() {
    let state = MockTrainingState::default();

    // Create a job
    let job = test_fixtures::create_test_job(
        "concurrent_watch",
        "DQN",
        TrainingStatus::Pending,
    );
    state.add_job(job);

    let addr = start_mock_server(state.clone()).await;

    // Spawn 16 concurrent watchers
    let mut handles = vec![];
    for i in 0..16 {
        let addr_clone = addr;
        let handle = tokio::spawn(async move {
            let channel = Channel::from_shared(format!("http://{}", addr_clone))
                .unwrap()
                .connect()
                .await
                .unwrap();

            let mut client = MlTrainingServiceClient::new(channel);

            let request = SubscribeToTrainingStatusRequest {
                job_id: "concurrent_watch".to_string(),
            };

            let mut stream = client
                .subscribe_to_training_status(request)
                .await
                .unwrap()
                .into_inner();

            // Read first update
            if let Some(update) = stream.next().await {
                assert!(update.is_ok());
            }

            i
        });
        handles.push(handle);
    }

    // Wait for all watchers
    for handle in handles {
        let result = handle.await.unwrap();
        assert!(result < 16);
    }
}

/// TEST 4: Resume watch after disconnect
#[tokio::test]
async fn test_resume_watch_after_disconnect() {
    let state = MockTrainingState::default();

    let job = test_fixtures::create_test_job(
        "resume_test",
        "PPO",
        TrainingStatus::Running,
    );
    state.add_job(job);

    let addr = start_mock_server(state.clone()).await;

    // First connection
    let channel1 = Channel::from_shared(format!("http://{}", addr))
        .unwrap()
        .connect()
        .await
        .unwrap();

    let mut client1 = MlTrainingServiceClient::new(channel1);

    let request1 = SubscribeToTrainingStatusRequest {
        job_id: "resume_test".to_string(),
    };

    let mut stream1 = client1
        .subscribe_to_training_status(request1)
        .await
        .unwrap()
        .into_inner();

    // Read one update then disconnect
    if let Some(update) = stream1.next().await {
        assert!(update.is_ok());
    }
    drop(stream1);

    // Reconnect
    let channel2 = Channel::from_shared(format!("http://{}", addr))
        .unwrap()
        .connect()
        .await
        .unwrap();

    let mut client2 = MlTrainingServiceClient::new(channel2);

    let request2 = SubscribeToTrainingStatusRequest {
        job_id: "resume_test".to_string(),
    };

    let mut stream2 = client2
        .subscribe_to_training_status(request2)
        .await
        .unwrap()
        .into_inner();

    // Should be able to resume
    if let Some(update) = stream2.next().await {
        assert!(update.is_ok());
    }
}

/// TEST 5: Terminal status auto-close
#[tokio::test]
async fn test_terminal_status_auto_close() {
    let state = MockTrainingState::default();

    let job = test_fixtures::create_test_job(
        "terminal_test",
        "TFT",
        TrainingStatus::Pending,
    );
    state.add_job(job);

    let addr = start_mock_server(state.clone()).await;

    let channel = Channel::from_shared(format!("http://{}", addr))
        .unwrap()
        .connect()
        .await
        .unwrap();

    let mut client = MlTrainingServiceClient::new(channel);

    let request = SubscribeToTrainingStatusRequest {
        job_id: "terminal_test".to_string(),
    };

    let mut stream = client
        .subscribe_to_training_status(request)
        .await
        .unwrap()
        .into_inner();

    // Collect all updates until stream ends
    let mut final_status = None;
    while let Some(update) = stream.next().await {
        let update = update.unwrap();
        final_status = Some(update.status);

        if update.progress_percentage >= 100.0 {
            break;
        }
    }

    assert_eq!(final_status, Some(TrainingStatus::Completed as i32));
}

/// TEST 6: Progress percentage validation
#[tokio::test]
async fn test_progress_percentage_validation() {
    let state = MockTrainingState::default();

    let job = test_fixtures::create_test_job(
        "progress_test",
        "MAMBA_2",
        TrainingStatus::Pending,
    );
    state.add_job(job);

    let addr = start_mock_server(state.clone()).await;

    let channel = Channel::from_shared(format!("http://{}", addr))
        .unwrap()
        .connect()
        .await
        .unwrap();

    let mut client = MlTrainingServiceClient::new(channel);

    let request = SubscribeToTrainingStatusRequest {
        job_id: "progress_test".to_string(),
    };

    let mut stream = client
        .subscribe_to_training_status(request)
        .await
        .unwrap()
        .into_inner();

    // Validate all progress values are 0-100
    let mut last_progress = 0.0;
    while let Some(update) = stream.next().await {
        let update = update.unwrap();
        assert!(update.progress_percentage >= 0.0);
        assert!(update.progress_percentage <= 100.0);
        assert!(update.progress_percentage >= last_progress, "Progress should be monotonic");
        last_progress = update.progress_percentage;

        if update.progress_percentage >= 100.0 {
            break;
        }
    }
}

/// TEST 7: Epoch counter validation
#[tokio::test]
async fn test_epoch_counter() {
    let state = MockTrainingState::default();

    let job = test_fixtures::create_test_job(
        "epoch_test",
        "DQN",
        TrainingStatus::Pending,
    );
    state.add_job(job);

    let addr = start_mock_server(state.clone()).await;

    let channel = Channel::from_shared(format!("http://{}", addr))
        .unwrap()
        .connect()
        .await
        .unwrap();

    let mut client = MlTrainingServiceClient::new(channel);

    let request = SubscribeToTrainingStatusRequest {
        job_id: "epoch_test".to_string(),
    };

    let mut stream = client
        .subscribe_to_training_status(request)
        .await
        .unwrap()
        .into_inner();

    let mut max_epoch = 0;
    while let Some(update) = stream.next().await {
        let update = update.unwrap();
        assert!(update.current_epoch <= update.total_epochs);
        max_epoch = update.current_epoch;

        if update.progress_percentage >= 100.0 {
            break;
        }
    }

    assert!(max_epoch > 0, "Should have progressed through epochs");
}

/// TEST 8: Non-existent job watch error
#[tokio::test]
async fn test_watch_nonexistent_job() {
    let state = MockTrainingState::default();
    let addr = start_mock_server(state).await;

    let channel = Channel::from_shared(format!("http://{}", addr))
        .unwrap()
        .connect()
        .await
        .unwrap();

    let mut client = MlTrainingServiceClient::new(channel);

    let request = SubscribeToTrainingStatusRequest {
        job_id: "nonexistent_job".to_string(),
    };

    let result = client.subscribe_to_training_status(request).await;
    assert!(result.is_err(), "Should error on non-existent job");
}

/// TEST 9: Stream timeout handling
#[tokio::test]
async fn test_stream_timeout() {
    let state = MockTrainingState::default();

    let job = test_fixtures::create_test_job(
        "timeout_test",
        "PPO",
        TrainingStatus::Pending,
    );
    state.add_job(job);

    let addr = start_mock_server(state).await;

    let channel = Channel::from_shared(format!("http://{}", addr))
        .unwrap()
        .connect()
        .await
        .unwrap();

    let mut client = MlTrainingServiceClient::new(channel);

    let request = SubscribeToTrainingStatusRequest {
        job_id: "timeout_test".to_string(),
    };

    let stream_future = client.subscribe_to_training_status(request);

    // Should complete within 5 seconds
    let result = tokio::time::timeout(Duration::from_secs(5), stream_future).await;
    assert!(result.is_ok(), "Stream should be established within timeout");
}

/// TEST 10: Status transition validation
#[tokio::test]
async fn test_status_transitions() {
    let state = MockTrainingState::default();

    let job = test_fixtures::create_test_job(
        "transition_test",
        "TFT",
        TrainingStatus::Pending,
    );
    state.add_job(job);

    let addr = start_mock_server(state).await;

    let channel = Channel::from_shared(format!("http://{}", addr))
        .unwrap()
        .connect()
        .await
        .unwrap();

    let mut client = MlTrainingServiceClient::new(channel);

    let request = SubscribeToTrainingStatusRequest {
        job_id: "transition_test".to_string(),
    };

    let mut stream = client
        .subscribe_to_training_status(request)
        .await
        .unwrap()
        .into_inner();

    let mut statuses = vec![];
    while let Some(update) = stream.next().await {
        let update = update.unwrap();
        statuses.push(update.status);

        if update.progress_percentage >= 100.0 {
            break;
        }
    }

    // Should see RUNNING → COMPLETED transition
    assert!(statuses.contains(&(TrainingStatus::Running as i32)));
    assert_eq!(statuses.last(), Some(&(TrainingStatus::Completed as i32)));
}