//! FlareDB 3-Node Region Failover Test
//!
//! Verifies Raft consensus, region leader election, and data persistence under node failures.

use flaredb_proto::kvrpc::kv_cas_client::KvCasClient;
use flaredb_proto::kvrpc::{CasRequest, GetRequest};
use std::time::Duration;
use tokio::time::sleep;
use tonic::transport::Channel;

/// Helper to start a FlareDB node (placeholder - would need actual Server struct)
/// NOTE: This test requires FlareDB server infrastructure to be refactored
/// to support programmatic multi-instance startup similar to Chainfire.
///
/// Current limitation: FlareDB main.rs doesn't expose Server struct for testing.
/// This is a skeleton showing the intended test structure.

#[tokio::test]
#[ignore] // Run with: cargo test --test region_failover -- --ignored
async fn test_3node_region_leader_election() {
    println!("\n=== Test: 3-Node FlareDB Region Leader Election ===");
    println!("NOTE: Test skeleton - requires FlareDB server refactoring for multi-instance support");

    // TODO: Start 3 FlareDB instances
    // - Node 1 (store_id=1): API 127.0.0.1:2479, Raft 127.0.0.1:2480
    // - Node 2 (store_id=2): API 127.0.0.1:2579, Raft 127.0.0.1:2580
    // - Node 3 (store_id=3): API 127.0.0.1:2679, Raft 127.0.0.1:2680
    //
    // All nodes configured with:
    // - Same region (id=1, start_key=[], end_key=[])
    // - Peer list: [1, 2, 3]
    // - Optional PD at localhost:9999

    // Wait for Raft leader election
    sleep(Duration::from_secs(2)).await;
    println!("Would verify Raft leader elected");

    // TODO: Connect to each node and verify one is leader
    // Expected: One node has raft_leader=1 metric
}

#[tokio::test]
#[ignore]
async fn test_3node_data_replication() {
    println!("\n=== Test: 3-Node Data Replication ===");
    println!("NOTE: Test skeleton - requires server infrastructure");

    // TODO: Start 3-node cluster (as above)

    // Connect to leader and write data
    println!("Would write data to region leader");
    // let channel = Channel::from_static("http://127.0.0.1:2479").connect().await?;
    // let mut client = KvCasClient::new(channel);
    //
    // let req = CasRequest {
    //     key: b"test-key".to_vec(),
    //     value: b"test-value".to_vec(),
    //     expected_version: 0,
    //     namespace: "default".to_string(),
    // };
    // client.compare_and_swap(req).await?;

    sleep(Duration::from_millis(500)).await;

    // Read from followers
    println!("Would read from follower nodes");
    // Verify data replicated to all nodes

    println!("✓ Data replication would be verified");
}

#[tokio::test]
#[ignore]
async fn test_3node_leader_crash_failover() {
    println!("\n=== Test: Region Leader Crash & Failover ===");
    println!("NOTE: Test skeleton - requires server infrastructure");

    // TODO: Start 3-node cluster

    // Write data to region
    println!("Would write test data");

    // Identify and kill region leader
    println!("Would kill region leader");

    // Wait for re-election
    sleep(Duration::from_secs(1)).await;

    // Verify new leader elected and data readable
    println!("Would verify new leader elected");
    println!("Would verify data still accessible");

    println!("✓ Leader failover would be verified");
}

#[tokio::test]
#[ignore]
async fn test_3node_quorum_maintenance() {
    println!("\n=== Test: Quorum Maintenance (2/3 Survives) ===");
    println!("NOTE: Test skeleton - requires server infrastructure");

    // TODO: Start 3-node cluster

    // Write initial data
    println!("Would write initial data");

    // Kill one node (non-leader)
    println!("Would kill one follower node");

    // Cluster should maintain 2/3 quorum
    println!("Would verify writes still succeed with 2/3 quorum");

    // Verify data readable from remaining nodes
    println!("Would verify data accessible from remaining nodes");

    println!("✓ Quorum maintenance would be verified");
}

// ============================================================================
// Working Example Test (using flaredb-client pattern from examples/test_cluster.rs)
// ============================================================================

#[tokio::test]
#[ignore]
async fn test_2node_basic_connectivity() {
    println!("\n=== Test: 2-Node Basic Connectivity ===");
    println!("Prerequisites: Two FlareDB servers must be running:");
    println!("  Node 1: http://127.0.0.1:50051");
    println!("  Node 2: http://127.0.0.1:50052");
    println!();

    // Connect to node 1
    let result1 = Channel::from_static("http://127.0.0.1:50051")
        .connect()
        .await;

    match result1 {
        Ok(channel) => {
            let mut client = KvCasClient::new(channel);

            // Write key
            println!("Writing key to node 1...");
            let req = CasRequest {
                key: b"integration-test-key".to_vec(),
                value: b"integration-test-value".to_vec(),
                expected_version: 0,
                namespace: "default".to_string(),
            };

            match client.compare_and_swap(req).await {
                Ok(resp) => {
                    let inner = resp.into_inner();
                    println!("✓ Write successful: version={}", inner.new_version);
                    assert!(inner.success);
                }
                Err(e) => {
                    println!("✗ Write failed: {}", e);
                    panic!("Write operation failed");
                }
            }

            // Read back
            println!("Reading key from node 1...");
            let req = GetRequest {
                key: b"integration-test-key".to_vec(),
                namespace: "default".to_string(),
            };

            match client.get(req).await {
                Ok(resp) => {
                    let inner = resp.into_inner();
                    println!(
                        "✓ Read successful: found={}, value={:?}",
                        inner.found,
                        String::from_utf8_lossy(&inner.value)
                    );
                    assert!(inner.found);
                    assert_eq!(&inner.value, b"integration-test-value");
                }
                Err(e) => {
                    println!("✗ Read failed: {}", e);
                    panic!("Read operation failed");
                }
            }
        }
        Err(e) => {
            println!("✗ Cannot connect to node 1: {}", e);
            println!("Skipping test - servers not running");
            return;
        }
    }

    // Try node 2 connectivity
    println!("\nTesting node 2 connectivity...");
    let result2 = Channel::from_static("http://127.0.0.1:50052")
        .connect()
        .await;

    match result2 {
        Ok(channel) => {
            let mut client2 = KvCasClient::new(channel);
            let req = GetRequest {
                key: b"integration-test-key".to_vec(),
                namespace: "default".to_string(),
            };

            match client2.get(req).await {
                Ok(resp) => {
                    let inner = resp.into_inner();
                    if inner.found {
                        println!(
                            "✓ Node 2 has replicated data: {:?}",
                            String::from_utf8_lossy(&inner.value)
                        );
                    } else {
                        println!("⚠ Node 2 doesn't have data yet (leader-only reads?)");
                    }
                }
                Err(e) => {
                    println!("⚠ Node 2 read error (expected if not leader): {}", e);
                }
            }
        }
        Err(e) => {
            println!("⚠ Cannot connect to node 2: {}", e);
        }
    }

    println!("\n✓ Basic connectivity test complete");
}