Add a leaderboard with Redis

board-server/Cargo.toml

@@ -15,3 +15,5 @@ tungstenite = "0.18.0"
 anyhow = "1.0.69"
 rand = "0.8.5"
 serde_json = "1.0.93"
+redis = { version = "0.22.3", features = ["aio", "async-std-comp"] }
+async-trait = "0.1.66"

board-server/src/leaderboard.rs

@@ -0,0 +1,62 @@
+use async_trait::async_trait;
+use redis::{AsyncCommands, RedisError};
+use std::env;
+
+const LEADERBOARD: &str = "leaderboard";
+type LeaderboardEntry = (String, i32);
+
+#[async_trait]
+trait Leaderboard {
+    async fn add_score(&self, player_name: &str, score: i32) -> Result<(), RedisError>;
+    async fn get_highscores(&self) -> Result<Vec<LeaderboardEntry>, RedisError>;
+}
+
+struct RedisLeaderboard {
+    client: redis::Client,
+}
+
+impl RedisLeaderboard {
+    fn new(client: redis::Client) -> Self {
+        Self { client }
+    }
+}
+
+#[async_trait]
+impl Leaderboard for RedisLeaderboard {
+    async fn add_score(&self, player_name: &str, score: i32) -> Result<(), RedisError> {
+        let mut con = self.client.get_async_connection().await?;
+        con.zadd(LEADERBOARD, player_name, score).await?;
+        Ok(())
+    }
+
+    async fn get_highscores(&self) -> Result<Vec<LeaderboardEntry>, RedisError> {
+        let mut con = self.client.get_async_connection().await?;
+        let count: isize = con.zcard(LEADERBOARD).await?;
+        let leaderboard: Vec<LeaderboardEntry> =
+            con.zrange_withscores(LEADERBOARD, 0, count - 1).await?;
+        Ok(leaderboard)
+    }
+}
+
+struct InMemoryLeaderboard();
+
+#[async_trait]
+impl Leaderboard for InMemoryLeaderboard {
+    async fn add_score(&self, _: &str, _: i32) -> Result<(), RedisError> {
+        Ok(())
+    }
+
+    async fn get_highscores(&self) -> Result<Vec<LeaderboardEntry>, RedisError> {
+        Ok(Vec::new())
+    }
+}
+
+async fn provide_leaderboard() -> Box<dyn Leaderboard> {
+    match env::var("REDIS_HOSTNAME") {
+        Ok(redis_host_name) => match redis::Client::open(format!("redis://{redis_host_name}/")) {
+            Ok(client) => Box::new(RedisLeaderboard::new(client)),
+            Err(_) => Box::new(InMemoryLeaderboard()),
+        },
+        Err(_) => Box::new(InMemoryLeaderboard()),
+    }
+}

board-server/src/main.rs

@@ -1,3 +1,4 @@
+mod leaderboard;
 mod player;
 mod room;