leaderboard and ranked systems

src/services/leaderboard.js

@@ -0,0 +1,73 @@
+const db = require('../db');
+
+async function upsertLeaderboardEntry(userId, grade, { elo, bestTime, correctAnswers = 0 } = {}) {
+  const existing = await db.leaderboardEntry.findUnique({
+    where: { userId_grade: { userId, grade } },
+  });
+
+  return db.leaderboardEntry.upsert({
+    where: { userId_grade: { userId, grade } },
+    create: {
+      userId,
+      grade,
+      elo: elo ?? 800,
+      bestTime: bestTime ?? null,
+      gamesPlayed: 1,
+      totalCorrect: correctAnswers,
+    },
+    update: {
+      ...(elo !== undefined && { elo }),
+      ...(bestTime !== undefined && existing?.bestTime == null || bestTime < (existing?.bestTime ?? Infinity)
+        ? { bestTime }
+        : {}),
+      gamesPlayed:  { increment: 1 },
+      totalCorrect: { increment: correctAnswers },
+    },
+  });
+}
+
+async function getLeaderboard(grade, sortBy = 'elo', limit = 10) {
+  const orderBy = sortBy === 'bestTime'
+    ? { bestTime: { sort: 'asc', nulls: 'last' } }
+    : { elo: 'desc' };
+
+  const entries = await db.leaderboardEntry.findMany({
+    where: { grade },
+    orderBy,
+    take: limit,
+    include: {
+      user: { select: { displayName: true, avatarUrl: true } },
+    },
+  });
+
+  return entries.map((entry, index) => ({ ...entry, rank: index + 1 }));
+}
+
+async function getUserRank(userId, grade, sortBy = 'elo') {
+  const entry = await db.leaderboardEntry.findUnique({
+    where: { userId_grade: { userId, grade } },
+  });
+
+  if (!entry) return null;
+
+  if (sortBy === 'bestTime') {
+    if (entry.bestTime === null) return { rank: null, entry };
+    const count = await db.leaderboardEntry.count({
+      where: {
+        grade,
+        AND: [
+          { bestTime: { not: null } },
+          { bestTime: { lt: entry.bestTime } },
+        ],
+      },
+    });
+    return { rank: count + 1, entry };
+  }
+
+  const count = await db.leaderboardEntry.count({
+    where: { grade, elo: { gt: entry.elo } },
+  });
+  return { rank: count + 1, entry };
+}
+
+module.exports = { upsertLeaderboardEntry, getLeaderboard, getUserRank };