const config = require("../config");
const logger = require("./logger");

class RateLimiter {
  constructor() {
    this.sentCount = 0;
    this.startTime = Date.now();
    this.lastSentTime = null;
  }

  // Record a successful send
  recordSuccess() {
    this.sentCount++;
    this.lastSentTime = Date.now();
  }

  // Get randomized delay between min and max
  getRandomDelay() {
    const baseDelay = config.app.delayMinutes * 60 * 1000; // Convert to ms
    const minDelay = baseDelay * 0.8; // 20% less than base
    const maxDelay = baseDelay * 1.2; // 20% more than base

    // Add additional randomization
    const randomFactor = Math.random() * (maxDelay - minDelay) + minDelay;

    // Add jitter to avoid patterns
    const jitter = (Math.random() - 0.5) * 30000; // +/- 30 seconds

    return Math.floor(randomFactor + jitter);
  }

  // Check if we should pause based on sent count
  shouldPause() {
    const hoursSinceStart = (Date.now() - this.startTime) / (1000 * 60 * 60);
    const emailsPerHour = this.sentCount / hoursSinceStart;

    // Gmail limits: ~500/day = ~20/hour
    // Be conservative: pause if exceeding 15/hour
    if (emailsPerHour > 15) {
      return true;
    }

    // Pause every 50 emails for 30 minutes
    if (this.sentCount > 0 && this.sentCount % 50 === 0) {
      return true;
    }

    return false;
  }

  // Get pause duration
  getPauseDuration() {
    // Standard pause: 30 minutes
    const basePause = 30 * 60 * 1000;

    // Add randomization to pause duration
    const randomPause = basePause + Math.random() * 10 * 60 * 1000; // +0-10 minutes

    return randomPause;
  }

  // Calculate next send time
  async getNextSendDelay() {
    if (this.shouldPause()) {
      const pauseDuration = this.getPauseDuration();
      const pauseMinutes = Math.round(pauseDuration / 60000);

      logger.rateLimitPause(
        pauseDuration,
        `Automatic pause after ${this.sentCount} emails`
      );
      console.log(`Rate limit pause: ${pauseMinutes} minutes`);
      return pauseDuration;
    }

    return this.getRandomDelay();
  }

  // Get human-readable time
  formatDelay(ms) {
    const minutes = Math.floor(ms / 60000);
    const seconds = Math.floor((ms % 60000) / 1000);
    return `${minutes}m ${seconds}s`;
  }

  // Reset counters (for testing)
  reset() {
    this.sentCount = 0;
    this.startTime = Date.now();
    this.lastSentTime = null;
  }

  // Get current stats
  getStats() {
    const runtime = (Date.now() - this.startTime) / 1000; // seconds
    const avgRate = this.sentCount / (runtime / 3600); // emails per hour

    return {
      sentCount: this.sentCount,
      runtime: Math.floor(runtime / 60), // minutes
      averageRate: avgRate.toFixed(1),
      nextDelay: this.formatDelay(this.getRandomDelay()),
    };
  }
}

module.exports = new RateLimiter();