smom-dbis-138/services/token-aggregation/src/api/middleware/cache.ts

import { Request, Response, NextFunction } from 'express';

interface CacheEntry {
  data: unknown;
  expiresAt: number;
}

const cache = new Map<string, CacheEntry>();
const DEFAULT_TTL = 60 * 1000; // 1 minute

export function cacheMiddleware(ttl: number = DEFAULT_TTL) {
  return (req: Request, res: Response, next: NextFunction) => {
    const key = `${req.method}:${req.originalUrl}`;
    const cached = cache.get(key);

    if (cached && cached.expiresAt > Date.now()) {
      return res.json(cached.data);
    }

    // Store original json method
    const originalJson = res.json.bind(res);

    // Override json method to cache response
    res.json = function (body: unknown) {
      cache.set(key, {
        data: body,
        expiresAt: Date.now() + ttl,
      });
      return originalJson(body);
    };

    next();
  };
}

export function clearCache(): void {
  cache.clear();
}

export function clearCacheForPattern(pattern: string): void {
  for (const key of cache.keys()) {
    if (key.includes(pattern)) {
      cache.delete(key);
    }
  }
}