/**
* Rate limiting service to prevent abuse
*/
import { logger } from '../utils/logger.js';
import type { RateLimitConfig, RateLimitInfo } from '../types/app-types.js';
import { RATE_LIMITS } from '../config/constants.js';
export class RateLimiter {
private requests = new Map<string, RateLimitInfo>();
constructor(private defaultConfig: RateLimitConfig = {
maxRequests: RATE_LIMITS.DEFAULT_MAX_REQUESTS,
windowMs: RATE_LIMITS.DEFAULT_WINDOW_MS
}) {}
/**
* Check if a request should be allowed based on rate limits
*/
public checkLimit(
identifier: string,
config: RateLimitConfig = this.defaultConfig
): boolean {
const now = Date.now();
const windowStart = now - config.windowMs;
// Get or create request history for this identifier
let info = this.requests.get(identifier);
if (!info) {
info = {
identifier,
requests: [],
lastRequest: 0
};
this.requests.set(identifier, info);
}
// Filter out requests outside the current window
info.requests = info.requests.filter(time => time > windowStart);
// Check if we've exceeded the limit
if (info.requests.length >= config.maxRequests) {
logger.rateLimit(identifier, config.maxRequests, config.windowMs);
return false;
}
// Record this request
info.requests.push(now);
info.lastRequest = now;
return true;
}
/**
* Get current request count for an identifier
*/
public getRequestCount(identifier: string, windowMs: number = this.defaultConfig.windowMs): number {
const info = this.requests.get(identifier);
if (!info) return 0;
const windowStart = Date.now() - windowMs;
return info.requests.filter(time => time > windowStart).length;
}
/**
* Clear old entries to prevent memory leaks
*/
public cleanup(): void {
const cutoff = Date.now() - (this.defaultConfig.windowMs * 2); // Keep double the window
for (const [identifier, info] of this.requests.entries()) {
if (info.lastRequest < cutoff) {
this.requests.delete(identifier);
}
}
logger.debug(`Rate limiter cleanup: ${this.requests.size} identifiers remaining`);
}
/**
* Reset rate limit for a specific identifier (for testing/admin)
*/
public reset(identifier: string): void {
this.requests.delete(identifier);
logger.debug(`Rate limit reset for identifier: ${identifier}`);
}
/**
* Get statistics about current rate limiting
*/
public getStats(): { totalIdentifiers: number; totalRequests: number } {
let totalRequests = 0;
for (const info of this.requests.values()) {
totalRequests += info.requests.length;
}
return {
totalIdentifiers: this.requests.size,
totalRequests
};
}
}
// Create singleton instance
export const rateLimiter = new RateLimiter();
// Cleanup interval to prevent memory leaks
setInterval(() => {
rateLimiter.cleanup();
}, RATE_LIMITS.DEFAULT_WINDOW_MS); // Cleanup every window period
