bedolaga-cabinet/src/utils/rateLimit.ts

/**
 * Client-side rate limiting utilities to prevent spam requests
 */

interface RateLimitEntry {
  count: number;
  resetTime: number;
}

const rateLimitStore = new Map<string, RateLimitEntry>();

/**
 * Check if action is rate limited
 * @param key Unique key for the action (e.g., 'payment', 'ticket-create')
 * @param maxRequests Maximum requests allowed in the time window
 * @param windowMs Time window in milliseconds
 * @returns true if action is allowed, false if rate limited
 */
export function checkRateLimit(
  key: string,
  maxRequests: number = 3,
  windowMs: number = 10000,
): boolean {
  const now = Date.now();
  const entry = rateLimitStore.get(key);

  // Clean up expired entry
  if (entry && now >= entry.resetTime) {
    rateLimitStore.delete(key);
  }

  const currentEntry = rateLimitStore.get(key);

  if (!currentEntry) {
    // First request - allow and start tracking
    rateLimitStore.set(key, {
      count: 1,
      resetTime: now + windowMs,
    });
    return true;
  }

  if (currentEntry.count >= maxRequests) {
    // Rate limit exceeded
    return false;
  }

  // Increment counter and allow
  currentEntry.count++;
  return true;
}

/**
 * Get remaining time until rate limit resets (in seconds)
 */
export function getRateLimitResetTime(key: string): number {
  const entry = rateLimitStore.get(key);
  if (!entry) return 0;
  const remaining = entry.resetTime - Date.now();
  return remaining > 0 ? Math.ceil(remaining / 1000) : 0;
}

/**
 * Reset rate limit for a key (e.g., after successful action)
 */
export function resetRateLimit(key: string): void {
  rateLimitStore.delete(key);
}

/**
 * Debounce function - delays execution until after wait ms have elapsed
 */
export function debounce<T extends (...args: unknown[]) => unknown>(
  func: T,
  wait: number,
): (...args: Parameters<T>) => void {
  let timeoutId: ReturnType<typeof setTimeout> | null = null;

  return (...args: Parameters<T>) => {
    if (timeoutId) {
      clearTimeout(timeoutId);
    }
    timeoutId = setTimeout(() => {
      func(...args);
      timeoutId = null;
    }, wait);
  };
}

/**
 * Throttle function - ensures function is called at most once per limit ms
 */
export function throttle<T extends (...args: unknown[]) => unknown>(
  func: T,
  limit: number,
): (...args: Parameters<T>) => void {
  let inThrottle = false;

  return (...args: Parameters<T>) => {
    if (!inThrottle) {
      func(...args);
      inThrottle = true;
      setTimeout(() => {
        inThrottle = false;
      }, limit);
    }
  };
}

// Rate limit keys for different actions
export const RATE_LIMIT_KEYS = {
  PAYMENT: 'payment',
  TICKET_CREATE: 'ticket-create',
  TICKET_REPLY: 'ticket-reply',
  PROMO_ACTIVATE: 'promo-activate',
  WHEEL_SPIN: 'wheel-spin',
} as const;