// file: crates/common/game-realtime-websocket-lib/tests/robustness.rs
// version: 1

//! Negative and bounded lifecycle tests for the WebSocket transport backend.

use futures_util::SinkExt; // rust-rules: trait-import
use game_realtime_transport_lib::RealtimeConnection; // rust-rules: trait-import
use game_realtime_transport_lib::RealtimeReceiver; // rust-rules: trait-import
use game_realtime_transport_lib::RealtimeSender; // rust-rules: trait-import

const SMALL_MESSAGE_LIMIT: usize = 32;
const TEST_TIMEOUT: std::time::Duration = std::time::Duration::from_secs(3);

type RawClient = tokio_tungstenite::WebSocketStream<tokio_tungstenite::MaybeTlsStream<tokio::net::TcpStream>>;

#[tokio::test(flavor = "current_thread")]
async fn outbound_payload_over_the_configured_limit_is_rejected_before_write() {
    let config = small_message_config();
    let (server_connection, client_connection) = establish_backend_pair(config).await;
    let (_server_sender, _server_receiver) = server_connection.split();
    let (mut client_sender, _client_receiver) = client_connection.split();
    let oversized = game_realtime_transport_lib::TransportMessage::new(vec![7; SMALL_MESSAGE_LIMIT + 1]);
    let result = client_sender.send(oversized).await;
    match result {
        Ok(()) => panic!("oversized outbound payload was accepted"),
        Err(error) => assert_eq!(error.kind(), game_realtime_transport_lib::TransportErrorKind::MessageTooLarge),
    }
}

#[tokio::test(flavor = "current_thread")]
async fn inbound_payload_over_the_configured_limit_is_rejected_by_tungstenite() {
    let config = small_message_config();
    let (server_connection, mut raw_client) = establish_backend_server_with_raw_client(config).await;
    let (_server_sender, mut server_receiver) = server_connection.split();
    let send = raw_client.send(tokio_tungstenite::tungstenite::Message::binary(vec![3; SMALL_MESSAGE_LIMIT + 1])).await;
    assert!(send.is_ok());
    let receive = tokio::time::timeout(TEST_TIMEOUT, server_receiver.receive()).await;
    match receive {
        Ok(Ok(value)) => panic!("oversized inbound payload produced a successful receive: {value:?}"),
        Ok(Err(error)) => assert_eq!(error.kind(), game_realtime_transport_lib::TransportErrorKind::MessageTooLarge),
        Err(_) => panic!("oversized inbound payload did not complete within the test timeout"),
    }
}

#[tokio::test(flavor = "current_thread")]
async fn text_message_is_rejected_by_the_binary_transport_contract() {
    let (server_connection, mut raw_client) = establish_backend_server_with_raw_client(game_realtime_websocket_lib::WebSocketConfig::default()).await;
    let (_server_sender, mut server_receiver) = server_connection.split();
    let send = raw_client.send(tokio_tungstenite::tungstenite::Message::text("text is outside the transport contract")).await;
    assert!(send.is_ok());
    let receive = tokio::time::timeout(TEST_TIMEOUT, server_receiver.receive()).await;
    match receive {
        Ok(Ok(value)) => panic!("text message produced a successful receive: {value:?}"),
        Ok(Err(error)) => assert_eq!(error.kind(), game_realtime_transport_lib::TransportErrorKind::Protocol),
        Err(_) => panic!("text-message rejection did not complete within the test timeout"),
    }
}

#[tokio::test(flavor = "current_thread")]
async fn peer_drop_without_close_handshake_is_reported_as_protocol_failure() {
    let (server_connection, raw_client) = establish_backend_server_with_raw_client(game_realtime_websocket_lib::WebSocketConfig::default()).await;
    let (_server_sender, mut server_receiver) = server_connection.split();
    drop(raw_client);
    let receive = tokio::time::timeout(TEST_TIMEOUT, server_receiver.receive()).await;
    match receive {
        Ok(Ok(value)) => panic!("abrupt peer drop was reported as a successful receive: {value:?}"),
        Ok(Err(error)) => assert_eq!(error.kind(), game_realtime_transport_lib::TransportErrorKind::Protocol),
        Err(_) => panic!("abrupt peer drop was not observed within the test timeout"),
    }
}

#[tokio::test(flavor = "current_thread")]
async fn silent_tcp_peer_hits_the_server_handshake_deadline() {
    let config = game_realtime_websocket_lib::WebSocketConfig::default().with_connect_timeout(std::time::Duration::from_millis(50));
    let bind_address = std::net::SocketAddr::from(([127, 0, 0, 1], 0));
    let listener = match game_realtime_websocket_lib::WebSocketListener::bind_with_config(bind_address, config).await {
        Ok(value) => value,
        Err(error) => panic!("bounded listener bind failed: {error}"),
    };
    let _silent_peer = match tokio::net::TcpStream::connect(listener.local_addr()).await {
        Ok(value) => value,
        Err(error) => panic!("silent TCP peer connection failed: {error}"),
    };
    let accept = tokio::time::timeout(TEST_TIMEOUT, listener.accept()).await;
    match accept {
        Ok(Ok(_connection)) => panic!("silent TCP peer unexpectedly completed a WebSocket handshake"),
        Ok(Err(error)) => assert_eq!(error.kind(), game_realtime_transport_lib::TransportErrorKind::Timeout),
        Err(_) => panic!("server handshake timeout did not fire within the outer test timeout"),
    }
}

fn small_message_config() -> game_realtime_websocket_lib::WebSocketConfig {
    return game_realtime_websocket_lib::WebSocketConfig::default().with_max_message_size(SMALL_MESSAGE_LIMIT).with_max_frame_size(SMALL_MESSAGE_LIMIT);
}

async fn establish_backend_pair(
    config: game_realtime_websocket_lib::WebSocketConfig,
) -> (game_realtime_websocket_lib::WebSocketConnection, game_realtime_websocket_lib::WebSocketConnection) {
    let bind_address = std::net::SocketAddr::from(([127, 0, 0, 1], 0));
    let listener = match game_realtime_websocket_lib::WebSocketListener::bind_with_config(bind_address, config).await {
        Ok(value) => value,
        Err(error) => panic!("loopback listener bind failed: {error}"),
    };
    let endpoint = format!("ws://{}/", listener.local_addr());
    let pair = tokio::time::timeout(TEST_TIMEOUT, async {
        return tokio::join!(listener.accept(), game_realtime_websocket_lib::connect_with_config(endpoint.as_str(), config));
    })
    .await;
    return match pair {
        Ok((Ok(server), Ok(client))) => (server, client),
        Ok((_server, _client)) => panic!("loopback connection establishment failed"),
        Err(_) => panic!("loopback connection establishment timed out"),
    };
}

async fn establish_backend_server_with_raw_client(
    config: game_realtime_websocket_lib::WebSocketConfig,
) -> (game_realtime_websocket_lib::WebSocketConnection, RawClient) {
    let bind_address = std::net::SocketAddr::from(([127, 0, 0, 1], 0));
    let listener = match game_realtime_websocket_lib::WebSocketListener::bind_with_config(bind_address, config).await {
        Ok(value) => value,
        Err(error) => panic!("loopback listener bind failed: {error}"),
    };
    let endpoint = format!("ws://{}/", listener.local_addr());
    let pair = tokio::time::timeout(TEST_TIMEOUT, async {
        return tokio::join!(listener.accept(), tokio_tungstenite::connect_async(endpoint.as_str()));
    })
    .await;
    return match pair {
        Ok((Ok(server), Ok((client, _response)))) => (server, client),
        Ok((_server, _client)) => panic!("raw-client loopback connection establishment failed"),
        Err(_) => panic!("raw-client loopback connection establishment timed out"),
    };
}