show leaderboard

1 files changed, 34 insertions, 0 deletions

diff --git a/src/state.rs b/src/state.rs
index ff5509b..9ad2f9a 100644
--- a/src/state.rs
+++ b/src/state.rs
@@ -76,6 +76,40 @@ impl Logic {
         state
     }
 
+    pub async fn get_leaderboard(&self) -> anyhow::Result<Vec<(String, u64, f64)>> {
+        let txn = self.database.begin_read()?;
+        let mut d = {
+            let raw = txn.open_table(T_IMPRESSIONS_RAW)?;
+            let weighted = txn.open_table(T_IMPRESSIONS_WEIGHTED)?;
+
+            weighted.iter()?.try_fold(Vec::new(), |mut s, k| {
+                let (k, v) = k?;
+                s.push((
+                    k.value().to_owned(),
+                    raw.get(k.value())?.map(|e| e.value()).unwrap_or_default(),
+                    v.value(),
+                ));
+                Ok::<_, anyhow::Error>(s)
+            })?
+        };
+
+        #[derive(PartialEq, PartialOrd)]
+        struct OrdAnyway(f64);
+        impl Eq for OrdAnyway {}
+        impl Ord for OrdAnyway {
+            fn cmp(&self, other: &Self) -> std::cmp::Ordering {
+                self.partial_cmp(other).unwrap()
+            }
+        }
+
+        d.sort_by_key(|(_, _, w)| OrdAnyway(*w));
+        while d.len() > 16 {
+            d.pop();
+        }
+
+        Ok(d)
+    }
+
     async fn commit_db(&self, mut rx: Receiver<ImpressionEvent>) -> anyhow::Result<()> {
         let mut deadline = None;
         let mut impressions_by_addr = vec![0u16; self.config.bloom_filter_size];