feat: start storing time series data

.gitignore

···
 .env
 *.log
 bun.lock
+data/

package.json

···
   "module": "src/index.ts",
   "type": "module",
   "private": true,
+  "scripts": {
+    "dev": "bun run --watch src/index.ts"
+  },
   "devDependencies": {
     "@types/bun": "latest"
   },

src/index.ts

···
 import sharp from "sharp";
 import { nanoid } from "nanoid";
+import { recordHit } from "./stats";
 
 // Configuration from env
 const R2_PUBLIC_URL = process.env.R2_PUBLIC_URL!;
···
           return new Response("Not found", { status: 404 });
         }
 
-        // Skip exists check - redirect directly, R2 will handle 404s
-        // This saves ~50-100ms per request
+        recordHit(imageKey);
+
         const r2PublicUrl = `${R2_PUBLIC_URL}/${imageKey}`;
         return Response.redirect(r2PublicUrl, 307);
       },

src/stats.ts

···
+import { Database } from "bun:sqlite";
+import { mkdirSync, existsSync } from "node:fs";
+import { dirname } from "node:path";
+
+const DB_PATH = process.env.STATS_DB_PATH || "./data/stats.db";
+
+const dbDir = dirname(DB_PATH);
+if (!existsSync(dbDir)) {
+  mkdirSync(dbDir, { recursive: true });
+}
+
+const db = new Database(DB_PATH, { create: true });
+
+db.exec("PRAGMA journal_mode = WAL");
+db.exec("PRAGMA synchronous = NORMAL"); // Safe with WAL, faster than FULL
+db.exec("PRAGMA busy_timeout = 5000");
+
+db.exec(`
+  CREATE TABLE IF NOT EXISTS image_stats (
+    image_key TEXT NOT NULL,
+    bucket_hour INTEGER NOT NULL,
+    hits INTEGER NOT NULL DEFAULT 1,
+    PRIMARY KEY (image_key, bucket_hour)
+  ) WITHOUT ROWID
+`);
+
+db.exec(`
+  CREATE INDEX IF NOT EXISTS idx_stats_time 
+  ON image_stats(bucket_hour, image_key)
+`);
+
+const incrementStmt = db.prepare(`
+  INSERT INTO image_stats (image_key, bucket_hour, hits)
+  VALUES (?1, ?2, 1)
+  ON CONFLICT(image_key, bucket_hour) DO UPDATE SET hits = hits + 1
+`);
+
+export function recordHit(imageKey: string): void {
+  const now = Math.floor(Date.now() / 1000);
+  const bucketHour = now - (now % 3600);
+  incrementStmt.run(imageKey, bucketHour);
+}
+
+export function getStats(imageKey: string, sinceDays: number = 30) {
+  const since = Math.floor(Date.now() / 1000) - sinceDays * 86400;
+  return db
+    .prepare(
+      `SELECT bucket_hour, hits FROM image_stats 
+       WHERE image_key = ? AND bucket_hour >= ? 
+       ORDER BY bucket_hour`
+    )
+    .all(imageKey, since);
+}
+
+export function getTopImages(sinceDays: number = 7, limit: number = 10) {
+  const since = Math.floor(Date.now() / 1000) - sinceDays * 86400;
+  return db
+    .prepare(
+      `SELECT image_key, SUM(hits) as total 
+       FROM image_stats WHERE bucket_hour >= ? 
+       GROUP BY image_key ORDER BY total DESC LIMIT ?`
+    )
+    .all(since, limit);
+}