1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
//! LAN matchmaking and socket implementation.
//!
//! ## Matchmaking
//!
//! The LAN matchmaker works by allowing the player to start a match and wait for people to join it,
//! or to join player's started match.
//!
//! Communication happens directly between LAN peers over the QUIC protocol.

// TODO
#![allow(missing_docs)]

use std::{net::IpAddr, time::Duration};

use iroh_net::{endpoint::get_remote_node_id, NodeAddr};
use mdns_sd::{ServiceDaemon, ServiceInfo};
use smallvec::SmallVec;
use tracing::warn;

use crate::networking::socket::establish_peer_connections;
use crate::utils::BiChannelServer;

use super::socket::Socket;
use super::*;

/// Service discover info and ping.
#[derive(Clone)]
pub struct ServerInfo {
    /// mutli-cast dns service discover info.
    pub service: ServiceInfo,
    /// The ping in milliseconds
    pub ping: Option<u16>,
}

/// Receiver for LAN service discovery channel.
#[derive(Clone)]
pub struct ServiceDiscoveryReceiver(mdns_sd::Receiver<mdns_sd::ServiceEvent>);

/// Channel used to do matchmaking over LAN.
///
/// Spawns a task to handle the actual matchmaking.
static LAN_MATCHMAKER: Lazy<LanMatchmaker> = Lazy::new(|| {
    let (client, server) = bi_channel();

    RUNTIME.spawn(async move {
        if let Err(err) = lan_matchmaker(server).await {
            warn!("lan matchmaker failed: {err:?}");
        }
    });

    LanMatchmaker(client)
});

static MDNS: Lazy<ServiceDaemon> =
    Lazy::new(|| ServiceDaemon::new().expect("Couldn't start MDNS service discovery thread."));

const MDNS_SERVICE_TYPE: &str = "_jumpy._udp.local.";

#[derive(DerefMut, Deref)]
struct Pinger(BiChannelClient<PingerRequest, PingerResponse>);

type PingerRequest = SmallVec<[IpAddr; 10]>;
type PingerResponse = SmallVec<[(IpAddr, Option<u16>); 10]>;

static PINGER: Lazy<Pinger> = Lazy::new(|| {
    let (client, server) = bi_channel();

    std::thread::spawn(move || pinger(server));

    Pinger(client)
});

/// Host a server.
///
/// The number of players is limited to `u32::MAX`.
pub fn start_server(server: ServerInfo, player_count: u32) {
    MDNS.register(server.service)
        .expect("Could not register MDNS service.");
    LAN_MATCHMAKER
        .try_send(LanMatchmakerRequest::StartServer { player_count })
        .unwrap();
}

/// Stop hosting a server.
pub fn stop_server(server: &ServerInfo) {
    if let Err(err) = stop_server_by_name(server.service.get_fullname()) {
        warn!("Lan: failed to stop server: {err:?}");
    }
}

/// Stop hosting a server specified by name. (Use [`ServiceInfo::get_fullname()`].)
fn stop_server_by_name(name: &str) -> anyhow::Result<()> {
    loop {
        match MDNS.unregister(name) {
            Ok(_) => break,
            Err(mdns_sd::Error::Again) => (),
            Err(e) => {
                anyhow::bail!("Error unregistering MDNS service: {e}")
            }
        }
    }
    Ok(())
}

/// Wait for players to join a hosted server.
pub fn wait_players(joined_players: &mut usize, server: &ServerInfo) -> Option<NetworkMatchSocket> {
    while let Ok(response) = LAN_MATCHMAKER.try_recv() {
        match response {
            LanMatchmakerResponse::ServerStarted => {}
            LanMatchmakerResponse::PlayerCount(count) => {
                *joined_players = count;
            }
            LanMatchmakerResponse::GameStarting {
                socket,
                player_idx,
                player_count: _,
            } => {
                info!(?player_idx, "Starting network game");
                if let Err(err) = stop_server_by_name(server.service.get_fullname()) {
                    warn!("Lan: failed to stop server: {err:?}");
                }
                return Some(NetworkMatchSocket(Arc::new(socket)));
            }
        }
    }
    None
}

/// Join a server hosted by someone else.
pub fn join_server(server: &ServerInfo) -> anyhow::Result<()> {
    let addr_raw = server
        .service
        .get_properties()
        .get_property_val_str("node-addr")
        .ok_or_else(|| anyhow::anyhow!("missing node-addr property from discovery"))?;
    let addr_raw = hex::decode(addr_raw)?;
    let addr: NodeAddr = postcard::from_bytes(&addr_raw)?;
    LAN_MATCHMAKER
        .try_send(lan::LanMatchmakerRequest::JoinServer { addr })
        .unwrap();
    Ok(())
}

/// Leave a joined server.
pub fn leave_server() {
    LAN_MATCHMAKER
        .try_send(LanMatchmakerRequest::StopJoin)
        .unwrap();
}

/// Wait for a joined game to start.
pub fn wait_game_start() -> Option<NetworkMatchSocket> {
    while let Ok(message) = LAN_MATCHMAKER.try_recv() {
        match message {
            LanMatchmakerResponse::ServerStarted | LanMatchmakerResponse::PlayerCount(_) => {}
            LanMatchmakerResponse::GameStarting {
                socket,
                player_idx,
                player_count: _,
            } => {
                info!(?player_idx, "Starting network game");
                return Some(NetworkMatchSocket(Arc::new(socket)));
            }
        }
    }
    None
}

/// Update server pings and turn on service discovery.
pub fn prepare_to_join(
    servers: &mut Vec<ServerInfo>,
    service_discovery_recv: &mut Option<ServiceDiscoveryReceiver>,
    ping_update_timer: &Timer,
) {
    // Update server pings
    if ping_update_timer.finished() {
        PINGER
            .try_send(
                servers
                    .iter()
                    .map(|x| *x.service.get_addresses().iter().next().unwrap())
                    .collect(),
            )
            .ok();
    }
    if let Ok(pings) = PINGER.try_recv() {
        for (server, ping) in pings {
            for info in servers.iter_mut() {
                if info.service.get_addresses().contains(&server) {
                    info.ping = ping;
                }
            }
        }
    }

    let events = service_discovery_recv.get_or_insert_with(|| {
        ServiceDiscoveryReceiver(
            MDNS.browse(MDNS_SERVICE_TYPE)
                .expect("Couldn't start service discovery"),
        )
    });

    while let Ok(event) = events.0.try_recv() {
        match event {
            mdns_sd::ServiceEvent::ServiceResolved(info) => {
                info!("Found lan service!");
                servers.push(lan::ServerInfo {
                    service: info,
                    ping: None,
                })
            }
            mdns_sd::ServiceEvent::ServiceRemoved(_, full_name) => {
                servers.retain(|server| server.service.get_fullname() != full_name);
            }
            _ => (),
        }
    }
}

/// Get the current host info or create a new one. When there's an existing
/// service but its `service_name` is different, the service is recreated and
/// only then the returned `bool` is `true`.
pub async fn prepare_to_host<'a>(
    host_info: &'a mut Option<ServerInfo>,
    service_name: &str,
) -> (bool, &'a mut ServerInfo) {
    let create_service_info = || async {
        info!("New service hosting");
        let ep = get_network_endpoint().await;
        let mut my_addr = ep.node_addr().await.expect("network endpoint dead");
        my_addr
            .info
            .direct_addresses
            .retain(std::net::SocketAddr::is_ipv4);
        let port = my_addr.info.direct_addresses.first().unwrap().port();
        let mut props = std::collections::HashMap::default();
        let addr_encoded = hex::encode(postcard::to_stdvec(&my_addr).unwrap());
        props.insert("node-addr".to_string(), addr_encoded);
        let service = mdns_sd::ServiceInfo::new(
            MDNS_SERVICE_TYPE,
            service_name,
            service_name,
            "",
            port,
            props,
        )
        .unwrap()
        .enable_addr_auto();
        ServerInfo {
            service,
            ping: None,
        }
    };

    if host_info.is_none() {
        let info = create_service_info().await;
        host_info.replace(info);
    }
    let service_info = host_info.as_mut().unwrap();

    let mut is_recreated = false;
    if service_info.service.get_hostname() != service_name {
        stop_server_by_name(service_info.service.get_fullname()).unwrap();
        is_recreated = true;
        *service_info = create_service_info().await;
    }
    (is_recreated, service_info)
}

/// Implementation of the lan matchmaker task.
///
/// This is a long-running tasks that listens for messages sent through the `LAN_MATCHMAKER`
/// channel.
async fn lan_matchmaker(
    matchmaker_channel: BiChannelServer<LanMatchmakerRequest, LanMatchmakerResponse>,
) -> anyhow::Result<()> {
    while let Ok(request) = matchmaker_channel.recv().await {
        match request {
            // Start server
            LanMatchmakerRequest::StartServer { player_count } => {
                if let Err(err) = lan_start_server(&matchmaker_channel, player_count).await {
                    warn!("lan server failed: {err:?}");
                }
                // Once we are done with server matchmaking
            }
            // Server not running or joining so do nothing
            LanMatchmakerRequest::StopServer => (),
            LanMatchmakerRequest::StopJoin => (),

            // Join a hosted match
            LanMatchmakerRequest::JoinServer { addr } => {
                if let Err(err) = lan_join_server(&matchmaker_channel, addr).await {
                    warn!("failed to join server: {err:?}");
                }
            }
        }
    }

    Ok(())
}

async fn lan_start_server(
    matchmaker_channel: &BiChannelServer<LanMatchmakerRequest, LanMatchmakerResponse>,
    mut player_count: u32,
) -> anyhow::Result<()> {
    info!("Starting LAN server");
    matchmaker_channel
        .send(LanMatchmakerResponse::ServerStarted)
        .await?;

    let mut connections = Vec::new();
    let ep = get_network_endpoint().await;

    loop {
        tokio::select! {
            next_request = matchmaker_channel.recv() => {
                match next_request? {
                    LanMatchmakerRequest::StartServer {
                        player_count: new_player_count,
                    } => {
                        connections.clear();
                        player_count = new_player_count;
                    }
                    LanMatchmakerRequest::StopServer => {
                        break;
                    }
                    LanMatchmakerRequest::StopJoin => {} // Not joining, so don't do anything
                    LanMatchmakerRequest::JoinServer { .. } => {
                        anyhow::bail!("Cannot join server while hosting server");
                    }
                }
            }

            // Handle new connections
            incomming = ep.accept() => {
                let Some(incomming) = incomming else {
                    anyhow::bail!("unable to accept new connections");
                };
                let result = async move {
                    let mut connecting = incomming.accept()?;
                    let alpn = connecting.alpn().await?;
                    anyhow::ensure!(alpn == PLAY_ALPN, "unexpected ALPN");
                    let conn = connecting.await?;
                    anyhow::Ok(conn)
                };

                match result.await {
                    Ok(conn) => {
                        connections.push(conn);
                        let current_players = connections.len() + 1;
                        info!(%current_players, "New player connection");
                    }
                    Err(err) => {
                        warn!("failed to accept connection: {:?}", err);
                        continue;
                    }
                }
            }
        }

        // Discard closed connections
        connections.retain(|conn| {
            if conn.close_reason().is_some() {
                info!("Player closed connection");
                false
            } else {
                true
            }
        });

        let current_players = connections.len();
        let target_players = player_count;
        info!(%current_players, %target_players);

        // If we're ready to start a match
        if connections.len() == (player_count - 1) as usize {
            info!("All players joined.");

            let endpoint = get_network_endpoint().await;

            // Tell all clients we're ready
            for (i, conn) in connections.iter().enumerate() {
                let mut peers = Vec::new();
                connections
                    .iter()
                    .enumerate()
                    .filter(|x| x.0 != i)
                    .for_each(|(i, conn)| {
                        let id = get_remote_node_id(conn).expect("invalid connection");
                        let mut addr = NodeAddr::new(id);
                        if let Some(info) = endpoint.remote_info(id) {
                            if let Some(relay_url) = info.relay_url {
                                addr = addr.with_relay_url(relay_url.relay_url);
                            }
                            addr = addr.with_direct_addresses(
                                info.addrs.into_iter().map(|addr| addr.addr),
                            );
                        }

                        peers.push((u32::try_from(i + 1).unwrap(), addr));
                    });

                let mut uni = conn.open_uni().await?;
                uni.write_all(&postcard::to_vec::<_, 20>(&MatchmakerNetMsg::MatchReady {
                    player_idx: (i + 1).try_into()?,
                    peers,
                    player_count,
                })?)
                .await?;
                uni.finish()?;
                uni.stopped().await?;
            }

            let connections = connections
                .into_iter()
                .enumerate()
                .map(|(i, c)| (u32::try_from(i + 1).unwrap(), c))
                .collect();

            // Send the connections to the game so that it can start the network match.
            matchmaker_channel
                .send(LanMatchmakerResponse::GameStarting {
                    socket: Socket::new(0, connections),
                    player_idx: 0,
                    player_count,
                })
                .await?;
            info!(player_idx=0, %player_count, "Matchmaking finished");

            // Break out of the server loop
            break;

            // If we don't have enough players yet, send the updated player count to the game.
        } else {
            matchmaker_channel
                .send(LanMatchmakerResponse::PlayerCount(current_players))
                .await?;
        }
    }

    Ok(())
}

async fn lan_join_server(
    matchmaker_channel: &BiChannelServer<LanMatchmakerRequest, LanMatchmakerResponse>,
    addr: NodeAddr,
) -> anyhow::Result<()> {
    let ep = get_network_endpoint().await;
    let conn = ep.connect(addr, PLAY_ALPN).await?;

    // Wait for match to start
    let mut uni = conn.accept_uni().await?;
    let bytes = uni.read_to_end(20).await?;
    let message: MatchmakerNetMsg = postcard::from_bytes(&bytes)?;

    match message {
        MatchmakerNetMsg::MatchReady {
            peers: peer_addrs,
            player_idx,
            player_count,
        } => {
            info!(%player_count, %player_idx, ?peer_addrs, "Matchmaking finished");

            let peer_connections =
                establish_peer_connections(player_idx, player_count, peer_addrs, Some(conn))
                    .await?;

            let socket = Socket::new(player_idx, peer_connections);
            info!("Connections established.");

            matchmaker_channel
                .send(LanMatchmakerResponse::GameStarting {
                    socket,
                    player_idx,
                    player_count,
                })
                .await?;
        }
    }
    Ok(())
}

#[derive(Serialize, Deserialize)]
enum MatchmakerNetMsg {
    MatchReady {
        /// The peers they have for the match, with the index in the array being the player index of the peer.
        peers: Vec<(u32, NodeAddr)>,
        /// The player index of the player getting the message.
        player_idx: u32,
        player_count: u32,
    },
}

/// The type of the `LAN_MATCHMAKER` channel.
#[derive(DerefMut, Deref)]
pub struct LanMatchmaker(BiChannelClient<LanMatchmakerRequest, LanMatchmakerResponse>);

/// A request that may be sent to the `LAN_MATCHMAKER`.
#[derive(Debug)]
pub enum LanMatchmakerRequest {
    /// Start matchmaker server
    StartServer {
        /// match player count
        player_count: u32,
    },
    /// Join server
    JoinServer {
        /// Node Addr
        addr: NodeAddr,
    },
    /// Stop matchmaking server
    StopServer,
    /// Stop joining match
    StopJoin,
}

/// A response that may come from the `LAN_MATCHMAKER`.
pub enum LanMatchmakerResponse {
    /// Server started
    ServerStarted,
    /// Server player count
    PlayerCount(usize),
    /// Game is starting
    GameStarting {
        /// Lan socket to game
        socket: Socket,
        /// Local player index
        player_idx: u32,
        /// Game player count
        player_count: u32,
    },
}

fn pinger(server: BiChannelServer<PingerRequest, PingerResponse>) {
    while let Ok(servers) = server.recv_blocking() {
        let mut pings = SmallVec::new();
        for server in servers {
            let start = Instant::now();
            let ping_result =
                ping_rs::send_ping(&server, Duration::from_secs(2), &[1, 2, 3, 4], None);

            let ping = if let Err(e) = ping_result {
                warn!("Error pinging {server}: {e:?}");
                None
            } else {
                Some((Instant::now() - start).as_millis() as u16)
            };

            pings.push((server, ping));
        }
        if server.send_blocking(pings).is_err() {
            break;
        }
    }
}