settled-reach/server/tests/game_loop.rs

//! E2E integration test: full game loop with input processing and snapshot generation
//! Tests the complete pipeline: client sends input → server processes → server sends snapshot

use bevy_app::prelude::*;
use settled_reach_server::bridge::framing::{read_framed, write_framed};
use settled_reach_server::bridge::tcp::TcpBridge;
use settled_reach_server::bridge::types::*;
use settled_reach_server::bridge::{BridgePlugin, BridgeResource};
use settled_reach_server::simulation::movement::{PlayerCharacter, TilePosition, WalkabilityMap};
use settled_reach_server::simulation::SimulationPlugin;
use std::io::{BufReader, BufWriter};
use std::net::{TcpListener, TcpStream};
use std::sync::mpsc;
use std::thread;
use std::time::Duration;

#[test]
fn player_moves_north_through_full_pipeline() {
    // Pre-bind listener to discover the port
    let listener = TcpListener::bind("127.0.0.1:0").expect("bind listener");
    let server_addr = listener.local_addr().expect("get local addr");
    let addr_str = server_addr.to_string();

    // Channel to signal when server is ready to accept
    let (ready_tx, ready_rx) = mpsc::channel();

    // Spawn server thread
    let server_handle = thread::spawn(move || {
        // Drop the pre-bound listener since TcpBridge::accept will bind its own
        drop(listener);

        // Signal we're about to accept
        ready_tx.send(()).expect("send ready signal");

        // Accept connection
        let bridge = TcpBridge::accept(&addr_str).expect("accept connection");
        eprintln!("Test server accepted connection");

        // Build app
        let mut app = App::new();
        app.add_plugins(SimulationPlugin);
        app.add_plugins(BridgePlugin);
        app.insert_resource(BridgeResource::new(bridge));
        app.insert_resource(WalkabilityMap::new(32, 32, 1));
        app.world_mut()
            .spawn((PlayerCharacter, TilePosition::new(16, 16, 0)));

        // Run one tick: receive input, process, validate movement, generate snapshot, send
        app.update();

        eprintln!("Server completed one update cycle");
    });

    // Wait for server thread to start
    ready_rx
        .recv_timeout(Duration::from_secs(2))
        .expect("server did not become ready");

    // Give server time to bind and call accept()
    thread::sleep(Duration::from_millis(100));

    // Client: connect and send input
    {
        let stream = TcpStream::connect(server_addr).expect("client connect");
        let mut reader = BufReader::new(stream.try_clone().expect("clone for reader"));
        let mut writer = BufWriter::new(stream);

        // Send PlayerInput: MoveNorth at tick 0
        let inputs = vec![PlayerInput {
            tick: 0,
            action: PlayerAction::MoveNorth,
        }];
        let payload = rmp_serde::to_vec_named(&inputs).expect("serialize inputs");
        write_framed(&mut writer, &payload).expect("send inputs");
        eprintln!("Client sent MoveNorth input");

        // Receive ObserverSnapshot
        let response = read_framed(&mut reader)
            .expect("read snapshot")
            .expect("not EOF");
        let snapshot: ObserverSnapshot =
            rmp_serde::from_slice(&response).expect("deserialize snapshot");

        eprintln!(
            "Client received snapshot: tick={}, entities={}",
            snapshot.tick,
            snapshot.entities.len()
        );

        // Verify snapshot
        assert_eq!(snapshot.tick, 1); // After one tick
        assert_eq!(snapshot.entities.len(), 1); // One entity (player)

        let player_entity = &snapshot.entities[0];
        // Player started at (16, 16, 0), moved north (y-1) to (16, 15, 0)
        // Render coords: (16.5, 15.5, 0)
        assert_eq!(player_entity.x, 16.5);
        assert_eq!(player_entity.y, 15.5);
        assert_eq!(player_entity.z, 0);
        assert!(matches!(player_entity.kind, EntityKind::Player));

        eprintln!(
            "Client verified player moved to ({}, {}, {})",
            player_entity.x, player_entity.y, player_entity.z
        );
    }

    // Wait for server thread
    server_handle.join().expect("server thread panicked");
}