1 files changed, 272 insertions, 0 deletions
diff --git a/planetwars-server/src/modules/bot_api.rs b/planetwars-server/src/modules/bot_api.rs
new file mode 100644
index 0000000..0ecbf71
--- /dev/null
+++ b/planetwars-server/src/modules/bot_api.rs
@@ -0,0 +1,272 @@
+pub mod pb {
+    tonic::include_proto!("grpc.planetwars.bot_api");
+}
+
+use std::collections::HashMap;
+use std::net::SocketAddr;
+use std::sync::{Arc, Mutex};
+use std::time::Duration;
+
+use runner::match_context::{EventBus, PlayerHandle, RequestError, RequestMessage};
+use runner::match_log::MatchLogger;
+use tokio::sync::{mpsc, oneshot};
+use tokio_stream::wrappers::UnboundedReceiverStream;
+use tonic;
+use tonic::transport::Server;
+use tonic::{Request, Response, Status, Streaming};
+
+use planetwars_matchrunner as runner;
+
+use crate::db;
+use crate::util::gen_alphanumeric;
+use crate::ConnectionPool;
+
+use super::matches::{MatchPlayer, RunMatch};
+
+pub struct BotApiServer {
+    conn_pool: ConnectionPool,
+    router: PlayerRouter,
+}
+
+/// Routes players to their handler
+#[derive(Clone)]
+struct PlayerRouter {
+    routing_table: Arc<Mutex<HashMap<String, SyncThingData>>>,
+}
+
+impl PlayerRouter {
+    pub fn new() -> Self {
+        PlayerRouter {
+            routing_table: Arc::new(Mutex::new(HashMap::new())),
+        }
+    }
+}
+
+impl Default for PlayerRouter {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+// TODO: implement a way to expire entries
+impl PlayerRouter {
+    fn put(&self, player_key: String, entry: SyncThingData) {
+        let mut routing_table = self.routing_table.lock().unwrap();
+        routing_table.insert(player_key, entry);
+    }
+
+    fn take(&self, player_key: &str) -> Option<SyncThingData> {
+        // TODO: this design does not allow for reconnects. Is this desired?
+        let mut routing_table = self.routing_table.lock().unwrap();
+        routing_table.remove(player_key)
+    }
+}
+
+#[tonic::async_trait]
+impl pb::bot_api_service_server::BotApiService for BotApiServer {
+    type ConnectBotStream = UnboundedReceiverStream<Result<pb::PlayerRequest, Status>>;
+
+    async fn connect_bot(
+        &self,
+        req: Request<Streaming<pb::PlayerRequestResponse>>,
+    ) -> Result<Response<Self::ConnectBotStream>, Status> {
+        // TODO: clean up errors
+        let player_key = req
+            .metadata()
+            .get("player_key")
+            .ok_or_else(|| Status::unauthenticated("no player_key provided"))?;
+
+        let player_key_str = player_key
+            .to_str()
+            .map_err(|_| Status::invalid_argument("unreadable string"))?;
+
+        let sync_data = self
+            .router
+            .take(player_key_str)
+            .ok_or_else(|| Status::not_found("player_key not found"))?;
+
+        let stream = req.into_inner();
+
+        sync_data.tx.send(stream).unwrap();
+        Ok(Response::new(UnboundedReceiverStream::new(
+            sync_data.server_messages,
+        )))
+    }
+
+    async fn create_match(
+        &self,
+        req: Request<pb::MatchRequest>,
+    ) -> Result<Response<pb::CreatedMatch>, Status> {
+        // TODO: unify with matchrunner module
+        let conn = self.conn_pool.get().await.unwrap();
+
+        let match_request = req.get_ref();
+
+        let opponent = db::bots::find_bot_by_name(&match_request.opponent_name, &conn)
+            .map_err(|_| Status::not_found("opponent not found"))?;
+        let opponent_code_bundle = db::bots::active_code_bundle(opponent.id, &conn)
+            .map_err(|_| Status::not_found("opponent has no code"))?;
+
+        let player_key = gen_alphanumeric(32);
+
+        let remote_bot_spec = Box::new(RemoteBotSpec {
+            player_key: player_key.clone(),
+            router: self.router.clone(),
+        });
+        let mut run_match = RunMatch::from_players(vec![
+            MatchPlayer::from_bot_spec(remote_bot_spec),
+            MatchPlayer::from_code_bundle(&opponent_code_bundle),
+        ]);
+        let created_match = run_match
+            .store_in_database(&conn)
+            .expect("failed to save match");
+        run_match.spawn(self.conn_pool.clone());
+
+        Ok(Response::new(pb::CreatedMatch {
+            match_id: created_match.base.id,
+            player_key,
+        }))
+    }
+}
+
+// TODO: please rename me
+struct SyncThingData {
+    tx: oneshot::Sender<Streaming<pb::PlayerRequestResponse>>,
+    server_messages: mpsc::UnboundedReceiver<Result<pb::PlayerRequest, Status>>,
+}
+
+struct RemoteBotSpec {
+    player_key: String,
+    router: PlayerRouter,
+}
+
+#[tonic::async_trait]
+impl runner::BotSpec for RemoteBotSpec {
+    async fn run_bot(
+        &self,
+        player_id: u32,
+        event_bus: Arc<Mutex<EventBus>>,
+        _match_logger: MatchLogger,
+    ) -> Box<dyn PlayerHandle> {
+        let (tx, rx) = oneshot::channel();
+        let (server_msg_snd, server_msg_recv) = mpsc::unbounded_channel();
+        self.router.put(
+            self.player_key.clone(),
+            SyncThingData {
+                tx,
+                server_messages: server_msg_recv,
+            },
+        );
+
+        let fut = tokio::time::timeout(Duration::from_secs(10), rx);
+        match fut.await {
+            Ok(Ok(client_messages)) => {
+                // let client_messages = rx.await.unwrap();
+                tokio::spawn(handle_bot_messages(
+                    player_id,
+                    event_bus.clone(),
+                    client_messages,
+                ));
+            }
+            _ => {
+                // ensure router cleanup
+                self.router.take(&self.player_key);
+            }
+        };
+
+        // If the player did not connect, the receiving half of `sender`
+        // will be dropped here, resulting in a time-out for every turn.
+        // This is fine for now, but
+        // TODO: provide a formal mechanism for player startup failure
+        Box::new(RemoteBotHandle {
+            sender: server_msg_snd,
+            player_id,
+            event_bus,
+        })
+    }
+}
+
+async fn handle_bot_messages(
+    player_id: u32,
+    event_bus: Arc<Mutex<EventBus>>,
+    mut messages: Streaming<pb::PlayerRequestResponse>,
+) {
+    while let Some(message) = messages.message().await.unwrap() {
+        let request_id = (player_id, message.request_id as u32);
+        event_bus
+            .lock()
+            .unwrap()
+            .resolve_request(request_id, Ok(message.content));
+    }
+}
+
+struct RemoteBotHandle {
+    sender: mpsc::UnboundedSender<Result<pb::PlayerRequest, Status>>,
+    player_id: u32,
+    event_bus: Arc<Mutex<EventBus>>,
+}
+
+impl PlayerHandle for RemoteBotHandle {
+    fn send_request(&mut self, r: RequestMessage) {
+        let res = self.sender.send(Ok(pb::PlayerRequest {
+            request_id: r.request_id as i32,
+            content: r.content,
+        }));
+        match res {
+            Ok(()) => {
+                // schedule a timeout. See comments at method implementation
+                tokio::spawn(schedule_timeout(
+                    (self.player_id, r.request_id),
+                    r.timeout,
+                    self.event_bus.clone(),
+                ));
+            }
+            Err(_send_error) => {
+                // cannot contact the remote bot anymore;
+                // directly mark all requests as timed out.
+                // TODO: create a dedicated error type for this.
+                // should it be logged?
+                println!("send error: {:?}", _send_error);
+                self.event_bus
+                    .lock()
+                    .unwrap()
+                    .resolve_request((self.player_id, r.request_id), Err(RequestError::Timeout));
+            }
+        }
+    }
+}
+
+// TODO: this will spawn a task for every request, which might not be ideal.
+// Some alternatives:
+//  - create a single task that manages all time-outs.
+//  - intersperse timeouts with incoming client messages
+//  - push timeouts upwards, into the matchrunner logic (before we hit the playerhandle).
+//    This was initially not done to allow timer start to be delayed until the message actually arrived
+//    with the player. Is this still needed, or is there a different way to do this?
+//
+async fn schedule_timeout(
+    request_id: (u32, u32),
+    duration: Duration,
+    event_bus: Arc<Mutex<EventBus>>,
+) {
+    tokio::time::sleep(duration).await;
+    event_bus
+        .lock()
+        .unwrap()
+        .resolve_request(request_id, Err(RequestError::Timeout));
+}
+
+pub async fn run_bot_api(pool: ConnectionPool) {
+    let router = PlayerRouter::new();
+    let server = BotApiServer {
+        router,
+        conn_pool: pool.clone(),
+    };
+
+    let addr = SocketAddr::from(([127, 0, 0, 1], 50051));
+    Server::builder()
+        .add_service(pb::bot_api_service_server::BotApiServiceServer::new(server))
+        .serve(addr)
+        .await
+        .unwrap()
+}