//! Transport trait contract tests for `GrpcTransport`.
//!
//! Mirrors the test patterns from `InProcessTransport` but over gRPC on localhost.

use std::collections::HashMap;
use std::net::SocketAddr;
use std::thread;
use std::time::Duration;

use tidaldb::replication::WalSegmentId;
use tidaldb::replication::shard::{RegionId, ShardId};
use tidaldb::replication::transport::{Transport, TransportError, WalSegmentPayload};

use tidal_net::GrpcTransport;
use tidal_net::config::GrpcTransportConfig;

/// Get a unique listen address using port 0 (OS-assigned).
/// Since tonic doesn't support port 0, we bind a TcpListener to find a free port.
fn free_addr() -> SocketAddr {
    let listener = std::net::TcpListener::bind("127.0.0.1:0").unwrap();
    listener.local_addr().unwrap()
}

fn make_config(
    shard: ShardId,
    listen: SocketAddr,
    peers: HashMap<ShardId, SocketAddr>,
) -> GrpcTransportConfig {
    GrpcTransportConfig {
        local_shard: shard,
        listen_addr: listen,
        peers,
        insecure: true,
        ..Default::default()
    }
}

fn make_payload(shard: ShardId, seqno: u64) -> WalSegmentPayload {
    WalSegmentPayload {
        id: WalSegmentId::new(RegionId::SINGLE, shard, seqno),
        bytes: vec![0xAB; 100],
        event_count: 5,
    }
}

/// Build two GrpcTransports on localhost that can talk to each other.
fn build_pair() -> (GrpcTransport, GrpcTransport) {
    let addr0 = free_addr();
    let addr1 = free_addr();

    let config0 = make_config(ShardId(0), addr0, HashMap::from([(ShardId(1), addr1)]));
    let config1 = make_config(ShardId(1), addr1, HashMap::from([(ShardId(0), addr0)]));

    let t0 = GrpcTransport::new(config0).expect("transport 0");
    let t1 = GrpcTransport::new(config1).expect("transport 1");

    // Give servers a moment to start.
    thread::sleep(Duration::from_millis(100));

    (t0, t1)
}

#[test]
fn send_and_receive_between_shards() {
    let (t0, t1) = build_pair();

    // Shard 0 sends to Shard 1.
    let payload = make_payload(ShardId(0), 42);
    t0.send_segment(ShardId(1), payload).unwrap();

    // Shard 1 receives it.
    let received = t1.recv_segment().unwrap();
    assert_eq!(received.id.seqno, 42);
    assert_eq!(received.event_count, 5);
    assert_eq!(received.bytes.len(), 100);
}

#[test]
fn send_to_unknown_peer_fails() {
    let addr0 = free_addr();
    let config0 = make_config(ShardId(0), addr0, HashMap::new());
    let t0 = GrpcTransport::new(config0).expect("transport 0");
    thread::sleep(Duration::from_millis(50));

    let result = t0.send_segment(ShardId(99), make_payload(ShardId(0), 1));
    assert!(result.is_err());
    assert!(matches!(
        result.unwrap_err(),
        TransportError::UnknownPeer(_)
    ));
}

#[test]
fn payload_too_large_rejected() {
    let addr0 = free_addr();
    let addr1 = free_addr();
    let config0 = make_config(ShardId(0), addr0, HashMap::from([(ShardId(1), addr1)]));
    let t0 = GrpcTransport::new(config0).expect("transport 0");
    thread::sleep(Duration::from_millis(50));

    let payload = WalSegmentPayload {
        id: WalSegmentId::new(RegionId::SINGLE, ShardId(0), 1),
        bytes: vec![0u8; 64 * 1024 * 1024 + 1],
        event_count: 0,
    };
    let result = t0.send_segment(ShardId(1), payload);
    assert!(result.is_err());
    assert!(matches!(
        result.unwrap_err(),
        TransportError::PayloadTooLarge { .. }
    ));
}

#[test]
fn local_shard_returns_correct_id() {
    let addr = free_addr();
    let config = make_config(ShardId(7), addr, HashMap::new());
    let t = GrpcTransport::new(config).expect("transport");
    assert_eq!(t.local_shard(), ShardId(7));
}

#[test]
fn multiple_segments_fifo_order() {
    let (t0, t1) = build_pair();

    for seq in 1..=5u64 {
        t0.send_segment(ShardId(1), make_payload(ShardId(0), seq))
            .unwrap();
    }

    // Brief pause to let segments flow through gRPC.
    thread::sleep(Duration::from_millis(50));

    for expected_seq in 1..=5u64 {
        let received = t1.recv_segment().unwrap();
        assert_eq!(received.id.seqno, expected_seq);
    }
}