handle personal leaderboards (pivotId)

src/controllers/stats/leaderboardController.ts

@@ -6,7 +6,7 @@ export const leaderboardController: RequestHandler = async (req, res) => {
     logger.debug(`data provided to ${req.path}: ${String(req.body)}`);
     const payload = JSON.parse(String(req.body)) as ILeaderboardRequest;
     res.json({
-        results: await getLeaderboard(payload.field, payload.before, payload.after)
+        results: await getLeaderboard(payload.field, payload.before, payload.after, payload.pivotId)
     });
 };
 
@@ -14,4 +14,5 @@ interface ILeaderboardRequest {
     field: string;
     before: number;
     after: number;
+    pivotId?: string;
 }

src/models/leaderboardModel.ts

@@ -1,4 +1,4 @@
-import { model, Schema } from "mongoose";
+import { Document, model, Schema, Types } from "mongoose";
 import { ILeaderboardEntryDatabase } from "../types/leaderboardTypes";
 
 const leaderboardEntrySchema = new Schema<ILeaderboardEntryDatabase>(
@@ -16,3 +16,9 @@ leaderboardEntrySchema.index({ leaderboard: 1 });
 leaderboardEntrySchema.index({ expiry: 1 }, { expireAfterSeconds: 0 }); // With this, MongoDB will automatically delete expired entries.
 
 export const Leaderboard = model<ILeaderboardEntryDatabase>("Leaderboard", leaderboardEntrySchema);
+
+// eslint-disable-next-line @typescript-eslint/ban-types
+export type TLeaderboardEntryDocument = Document<unknown, {}, ILeaderboardEntryDatabase> & {
+    _id: Types.ObjectId;
+    __v: number;
+} & ILeaderboardEntryDatabase;

src/services/leaderboardService.ts

@@ -1,4 +1,4 @@
-import { Leaderboard } from "../models/leaderboardModel";
+import { Leaderboard, TLeaderboardEntryDocument } from "../models/leaderboardModel";
 import { ILeaderboardEntryClient } from "../types/leaderboardTypes";
 
 export const submitLeaderboardScore = async (
@@ -29,14 +29,42 @@ export const submitLeaderboardScore = async (
 export const getLeaderboard = async (
     leaderboard: string,
     before: number,
-    after: number
+    after: number,
+    pivotId: string | undefined = undefined
 ): Promise<ILeaderboardEntryClient[]> => {
-    const entries = await Leaderboard.find({ leaderboard })
+    let entries: TLeaderboardEntryDocument[];
+    let r: number;
+    if (pivotId) {
+        const pivotDoc = await Leaderboard.findOne({ leaderboard, accountId: pivotId });
+        if (!pivotDoc) {
+            return [];
+        }
+        const beforeDocs = await Leaderboard.find({
+            leaderboard,
+            score: { $gt: pivotDoc.score }
+        })
+            .sort({ score: 1 })
+            .limit(before);
+        const afterDocs = await Leaderboard.find({
+            leaderboard,
+            score: { $lt: pivotDoc.score }
+        })
+            .sort({ score: -1 })
+            .limit(after);
+        entries = [...beforeDocs.reverse(), pivotDoc, ...afterDocs];
+        r =
+            (await Leaderboard.countDocuments({
+                leaderboard,
+                score: { $gt: pivotDoc.score }
+            })) - beforeDocs.length;
+    } else {
+        entries = await Leaderboard.find({ leaderboard })
             .sort({ score: -1 })
             .skip(before)
             .limit(after - before);
+        r = before;
+    }
     const res: ILeaderboardEntryClient[] = [];
-    let r = before;
     for (const entry of entries) {
         res.push({
             _id: entry.accountId.toString(),