feat: implement PNID and NEXToken metrics

src/metrics.ts

@@ -1,10 +1,38 @@
 import { format } from 'node:util';
+import { Gauge } from 'prom-client';
 import expressMetrics from 'express-prom-bundle';
 import express from 'express';
 import { LOG_ERROR, LOG_INFO, LOG_SUCCESS } from '@/logger';
 import { config } from '@/config-manager';
+import { PNID } from '@/models/pnid';
+import { NEXToken } from '@/models/nex-token';
 import type { Express, NextFunction, Request, Response } from 'express';
 
+export const pnidTotalGauge = new Gauge({
+	name: 'pn_account_pnid_total',
+	help: 'Total number of registered PNIDs',
+	async collect(): Promise<void> {
+		// * Aggregations are faster on large collections
+		const [result] = await PNID.aggregate<{ n: number } | undefined>([
+			{ $match: { deleted: false } },
+			{ $count: 'n' }
+		]);
+		this.set(result?.n ?? 0);
+	}
+});
+
+export const nexTokenTotalGauge = new Gauge({
+	name: 'pn_account_nex_token_total',
+	help: 'Total number of NEX tokens',
+	async collect(): Promise<void> {
+		// * Aggregations are faster on large collections
+		const [result] = await NEXToken.aggregate<{ n: number } | undefined>([
+			{ $count: 'n' }
+		]);
+		this.set(result?.n ?? 0);
+	}
+});
+
 export function registerMetrics(app: Express): Express {
 	const metrics = express();
 

src/models/pnid.ts

@@ -144,6 +144,9 @@ PNIDSchema.index({ 'pid': 1, 'username': 1, 'connections.discord.id': 1 });
 
 PNIDSchema.plugin(uniqueValidator, { message: '{PATH} already in use.' });
 
+// * Used by metrics
+PNIDSchema.index({ deleted: 1 });
+
 /*
 	According to http://pf2m.com/tools/rank.php Nintendo PID's start at 1,800,000,000 and count down with each account
 	This means the max PID is 1799999999 and hard-limits the number of potential accounts to 1,800,000,000