Mebbling/lib/rate-limit.ts

import { db } from "@/lib/db";

/** SQLite-backed fixed-window limiter shared by every Web container using this database. */
export function withinRateLimit(bucket: string, limit = 30, windowMs = 60_000) {
  const now = Date.now();
  const transaction = db.transaction(() => {
    const found = db.prepare("SELECT count,reset_at FROM rate_limits WHERE bucket=?").get(bucket) as { count: number; reset_at: number } | undefined;
    if (!found || found.reset_at <= now) {
      db.prepare("INSERT INTO rate_limits(bucket,count,reset_at) VALUES(?,?,?) ON CONFLICT(bucket) DO UPDATE SET count=excluded.count,reset_at=excluded.reset_at").run(bucket, 1, now + windowMs);
      return true;
    }
    if (found.count >= limit) return false;
    db.prepare("UPDATE rate_limits SET count=count+1 WHERE bucket=?").run(bucket);
    return true;
  });
  const allowed = transaction();
  if (Math.random() < 0.01) db.prepare("DELETE FROM rate_limits WHERE reset_at<?").run(now);
  return allowed;
}