lavina/src/core/room.rs

//! Domain of rooms — chats with multiple participants.
use std::{
    collections::HashMap,
    hash::Hash,
    sync::{Arc, RwLock},
};

use prometheus::{IntGauge, Registry as MetricRegistry};
use tokio::sync::RwLock as AsyncRwLock;

use crate::{
    core::player::{PlayerHandle, PlayerId},
    prelude::*,
};

use super::player::ConnectionId;

/// Opaque room id
#[derive(Debug, Clone, PartialEq, Eq, Hash)]
pub struct RoomId(pub ByteVec);

/// Shared datastructure for storing metadata about rooms.
#[derive(Clone)]
pub struct RoomRegistry(Arc<RwLock<RoomRegistryInner>>);
impl RoomRegistry {
    pub fn empty(metrics: &mut MetricRegistry) -> Result<RoomRegistry> {
        let metric_active_rooms =
            IntGauge::new("chat_rooms_active", "Number of alive room actors")?;
        metrics.register(Box::new(metric_active_rooms.clone()))?;
        let inner = RoomRegistryInner {
            rooms: HashMap::new(),
            metric_active_rooms,
        };
        Ok(RoomRegistry(Arc::new(RwLock::new(inner))))
    }

    pub fn get_or_create_room(&mut self, room_id: RoomId) -> RoomHandle {
        let mut inner = self.0.write().unwrap();
        if let Some(room_handle) = inner.rooms.get(&room_id) {
            room_handle.clone()
        } else {
            let room = Room {
                room_id: room_id.clone(),
                subscriptions: HashMap::new(),
            };
            let room_handle = RoomHandle(Arc::new(AsyncRwLock::new(room)));
            inner.rooms.insert(room_id, room_handle.clone());
            inner.metric_active_rooms.inc();
            room_handle
        }
    }

    pub fn get_room(&self, room_id: RoomId) -> Option<RoomHandle> {
        let inner = self.0.read().unwrap();
        let res = inner.rooms.get(&room_id);
        res.map(|r| r.clone())
    }
}

struct RoomRegistryInner {
    rooms: HashMap<RoomId, RoomHandle>,
    metric_active_rooms: IntGauge,
}

#[derive(Clone)]
pub struct RoomHandle(Arc<AsyncRwLock<Room>>);
impl RoomHandle {
    pub async fn subscribe(&mut self, player_id: PlayerId, player_handle: PlayerHandle) {
        let mut lock = self.0.write().await;
        lock.add_subscriber(player_id, player_handle);
    }

    pub async fn send_message(
        &mut self,
        player_id: PlayerId,
        connection_id: ConnectionId,
        body: String,
    ) {
        let lock = self.0.read().await;
        lock.send_message(player_id, connection_id, body).await;
    }
}

struct Room {
    room_id: RoomId,
    subscriptions: HashMap<PlayerId, PlayerHandle>,
}
impl Room {
    fn add_subscriber(&mut self, player_id: PlayerId, player_handle: PlayerHandle) {
        tracing::info!("Adding a subscriber to room");
        self.subscriptions.insert(player_id, player_handle);
    }

    async fn send_message(&self, player_id: PlayerId, connection_id: ConnectionId, body: String) {
        tracing::info!("Adding a message to room");
        for (_, sub) in &self.subscriptions {
            log::info!("Sending a message from room to player");
            sub.receive_message(
                self.room_id.clone(),
                player_id.clone(),
                connection_id.clone(),
                body.clone(),
            )
            .await;
        }
    }
}