Add persistent player leaderboards from game telemetry

src/routes/api/leaderboard/+server.ts

@@ -0,0 +1,26 @@
+import { json } from '@sveltejs/kit';
+import { getLeaderboard, isLeaderboardMetric, MAX_LEADERBOARD_OFFSET } from '$lib/server/fleet/leaderboard.js';
+
+export function GET({ url }: { url: URL }) {
+    const params = url.searchParams;
+    const game = params.get('game');
+    const map = params.get('map');
+    const metric = params.get('metric');
+    const q = params.get('q');
+    const rawLimit = params.get('limit');
+    const rawOffset = params.get('offset');
+    const integer = (value: string | null, fallback: number) => value === null ? fallback
+        : /^\d+$/.test(value) && Number.isSafeInteger(Number(value)) ? Number(value) : NaN;
+    const limit = integer(rawLimit, 50);
+    const offset = integer(rawOffset, 0);
+    if ((game !== null && game !== 't5' && game !== 't6')
+        || (map !== null && map.length > 1024) || (q !== null && q.length > 100)
+        || (metric !== null && !isLeaderboardMetric(metric))
+        || !Number.isFinite(limit) || limit < 1 || limit > 100
+        || !Number.isFinite(offset) || offset < 0 || offset > MAX_LEADERBOARD_OFFSET) {
+        return json({ ok: false, kind: 'bad-request', error: 'Use game t5 or t6, a supported metric, map key up to 1024 characters, q up to 100 characters, limit 1–100, and offset 0–1000000.' }, { status: 400 });
+    }
+    return json(getLeaderboard({ game: game ?? undefined, map: map || undefined,
+        metric: metric !== null && isLeaderboardMetric(metric) ? metric : undefined,
+        q: q ?? undefined, limit, offset }));
+}