Add Metrics tab with historical server utilization and map capacity

src/lib/server/fleet/metrics.ts

@@ -0,0 +1,78 @@
+import { db } from '../db/index.js';
+import { ONLINE_MAX_MS } from '../../server-freshness.js';
+
+export interface MetricSample {
+    server: string;
+    game: string;
+    map: string;
+    players: number | null;
+    capacity: number | null;
+}
+
+export function recordMetrics(samples: MetricSample[], at = Date.now()): void {
+    const handle = db();
+    handle.transaction(() => {
+        const insert = handle.prepare('INSERT OR REPLACE INTO metric_samples (at, server, game, map, players, capacity) VALUES (?, ?, ?, ?, ?, ?)');
+        for (const s of samples) insert.run(at, s.server, s.game, s.map, s.players, s.capacity);
+        handle.prepare('DELETE FROM metric_samples WHERE at < ?').run(at - 31 * 86400_000);
+    })();
+}
+
+export interface Utilization {
+    observed: number;
+    active: number;
+    idle: number;
+    unknown: number;
+    playerHours: number;
+}
+export interface MapMetrics extends Utilization {
+    game: string;
+    map: string;
+    full: number;
+    capacityObserved: number;
+}
+
+/** Treat each observation as valid until the next poll, capped at the freshness limit.
+ * Longer collection gaps are excluded, never interpreted as empty servers. */
+export function readMetrics(days: number, now = Date.now()) {
+    const since = now - days * 86400_000;
+    const bucketMs = days === 1 ? 3600_000 : 86400_000;
+    const handle = db();
+    const cte = `WITH times AS (
+        SELECT at, LEAD(at, 1, @now) OVER (ORDER BY at) AS next_at
+        FROM (SELECT DISTINCT at FROM metric_samples WHERE at >= @since - @fresh AND at <= @now)
+    ), samples AS (
+        SELECT s.*, MAX(0, MIN(t.next_at, s.at + @fresh, @now) - MAX(s.at, @since)) / 3600000.0 AS hours
+        FROM metric_samples s JOIN times t ON t.at = s.at
+    )`;
+    const params = { now, since, fresh: ONLINE_MAX_MS };
+    const totals = `COALESCE(SUM(CASE WHEN players IS NOT NULL THEN hours ELSE 0 END), 0) AS observed,
+        COALESCE(SUM(CASE WHEN players > 0 THEN hours ELSE 0 END), 0) AS active,
+        COALESCE(SUM(CASE WHEN players = 0 THEN hours ELSE 0 END), 0) AS idle,
+        COALESCE(SUM(CASE WHEN players IS NULL THEN hours ELSE 0 END), 0) AS unknown,
+        COALESCE(SUM(players * hours), 0) AS playerHours`;
+    const summary = handle.prepare(`${cte} SELECT ${totals} FROM samples`).get(params) as Utilization;
+    const servers = handle.prepare(`${cte} SELECT server, ${totals} FROM samples GROUP BY server ORDER BY active DESC, server`).all(params) as (Utilization & { server: string })[];
+    const maps = handle.prepare(`${cte}, pressure AS (
+        SELECT game, map, at, MAX(hours) AS hours,
+            MIN(CASE WHEN players IS NOT NULL AND capacity > 0 THEN 1 ELSE 0 END) AS known,
+            MIN(CASE WHEN players >= capacity AND capacity > 0 THEN 1 ELSE 0 END) AS full
+        FROM samples GROUP BY game, map, at
+    ), map_pressure AS (
+        SELECT game, map, SUM(CASE WHEN known = 1 THEN hours ELSE 0 END) AS capacityObserved,
+            SUM(CASE WHEN known = 1 AND full = 1 THEN hours ELSE 0 END) AS full
+        FROM pressure GROUP BY game, map
+    ) SELECT s.game, s.map, ${totals}, p.full, p.capacityObserved
+        FROM samples s JOIN map_pressure p ON p.game = s.game AND p.map = s.map
+        GROUP BY s.game, s.map ORDER BY playerHours DESC, s.map`).all(params) as MapMetrics[];
+    // Split intervals at chart boundaries so a midnight poll cannot shift time into the wrong day.
+    const points: (Utilization & { at: number })[] = [];
+    for (let at = Math.floor(since / bucketMs) * bucketMs; at < now; at += bucketMs) {
+        const end = Math.min(at + bucketMs, now);
+        const start = Math.max(at, since);
+        const point = handle.prepare(`${cte} SELECT ${totals} FROM samples`)
+            .get({ ...params, since: start, now: end }) as Utilization;
+        points.push({ at, ...point });
+    }
+    return { days, since, now, summary, servers, maps, points };
+}