import Database from 'better-sqlite3';
interface RateLimitStats {
totalRequests: number;
windowRequests: number;
remaining: number;
resetIn: number; // seconds
}
export class RateLimiter {
public db: Database.Database;
private windowMs: number;
private maxRequests: number;
constructor(dbPath: string = ':memory:', options?: { windowMs?: number; maxRequests?: number }) {
this.windowMs = options?.windowMs ?? 180000; // 3 minutes
this.maxRequests = options?.maxRequests ?? 12;
this.db = new Database(dbPath);
this.initialize();
}
private initialize(): void {
this.db.exec(`
CREATE TABLE IF NOT EXISTS rate_limit_log (
id INTEGER PRIMARY KEY AUTOINCREMENT,
timestamp INTEGER NOT NULL
)
`);
this.db.exec(`
CREATE INDEX IF NOT EXISTS idx_rate_limit_log_timestamp
ON rate_limit_log(timestamp)
`);
}
private cleanupOldEntries(now: number): void {
const cutoff = now - this.windowMs;
this.db.prepare('DELETE FROM rate_limit_log WHERE timestamp < ?').run(cutoff);
}
async checkRateLimit(): Promise<{ allowed: boolean; remaining: number; resetIn: number }> {
const now = Date.now();
// Cleanup first to keep the table small
this.cleanupOldEntries(now);
const windowStart = now - this.windowMs;
const countRow = this.db
.prepare('SELECT COUNT(*) as count FROM rate_limit_log WHERE timestamp > ?')
.get(windowStart) as { count: number };
const currentCount = countRow.count;
const remainingBefore = Math.max(0, this.maxRequests - currentCount);
if (currentCount >= this.maxRequests) {
// Reset in is the remaining time in the current window (approximation)
const resetIn = Math.ceil((this.windowMs - (now - windowStart)) / 1000);
return { allowed: false, remaining: 0, resetIn };
}
// Record this request
this.db.prepare('INSERT INTO rate_limit_log (timestamp) VALUES (?)').run(now);
const remainingAfter = Math.max(0, remainingBefore - 1);
const resetIn = Math.ceil((this.windowMs - (now - windowStart)) / 1000);
return { allowed: true, remaining: remainingAfter, resetIn };
}
getStats(): RateLimitStats {
const now = Date.now();
const windowStart = now - this.windowMs;
const totalRow = this.db
.prepare('SELECT COUNT(*) as count FROM rate_limit_log')
.get() as { count: number };
const windowRow = this.db
.prepare('SELECT COUNT(*) as count FROM rate_limit_log WHERE timestamp > ?')
.get(windowStart) as { count: number };
const windowRequests = windowRow.count;
const remaining = Math.max(0, this.maxRequests - windowRequests);
const resetIn = Math.ceil((this.windowMs - (now - windowStart)) / 1000);
return {
totalRequests: totalRow.count,
windowRequests,
remaining,
resetIn,
};
}
reset(): void {
this.db.exec('DELETE FROM rate_limit_log');
}
close(): void {
this.db.close();
}
}
