class RateLimiter {
  constructor({ windowMs, maxRequests }) {
    // windowMs is the time window in milliseconds (e.g., 15 minutes = 15 * 60 * 1000)
    this.windowMs = windowMs;
    // maxRequests is the number of allowed requests in the given window
    this.maxRequests = maxRequests;
    // in-memory store to keep track of requests per client
    this.clients = new Map();
  }

  handleRequest(clientId) {
    const currentTime = Date.now();

    // Check if the client has made requests in the current window
    if (this.clients.has(clientId)) {
      const clientData = this.clients.get(clientId);
      const { requestCount, startTime } = clientData;

      // If the current time is within the window, check the request count
      if (currentTime - startTime < this.windowMs) {
        if (requestCount >= this.maxRequests) {
          return { allowed: false, remainingTime: (startTime + this.windowMs - currentTime) };
        }
        // If not exceeding the maxRequests, increment the count
        clientData.requestCount += 1;
        this.clients.set(clientId, clientData);
        return { allowed: true, remainingRequests: this.maxRequests - clientData.requestCount };
      }
    }

    // Reset or start a new window for the client
    this.clients.set(clientId, { requestCount: 1, startTime: currentTime });
    return { allowed: true, remainingRequests: this.maxRequests - 1 };
  }

  // Function to clear expired clients from the store (optional for memory optimization)
  clearExpiredClients() {
    const currentTime = Date.now();
    this.clients.forEach((clientData, clientId) => {
      if (currentTime - clientData.startTime > this.windowMs) {
        this.clients.delete(clientId);
      }
    });
  }
}

module.exports = RateLimiter;