"use strict";

const { TooManyRequestsError } = require("../../errors");

function getClientIp(req) {
  return (
    req.ip ||
    req.headers["x-forwarded-for"]?.split(",")[0]?.trim() ||
    req.socket?.remoteAddress ||
    "127.0.0.1"
  );
}

class RateLimiter {
  /**
   * @param {Object} options
   * @param {number} [options.windowMs=900000] - 15 минут
   * @param {number} [options.max=5] - Максимум попыток
   * @param {import('../../logger').Logger} [options.logger]
   */
  constructor({ windowMs = 15 * 60 * 1000, max = 5, logger = null }) {
    this.windowMs = windowMs;
    this.max = max;
    this.logger = logger;
    /** @type {Map<string, number[]>} IP -> array of failure timestamps */
    this.failures = new Map();

    this._cleanupInterval = setInterval(() => this.cleanup(), this.windowMs);
    if (this._cleanupInterval.unref) {
      this._cleanupInterval.unref();
    }
  }

  middleware() {
    return (req, res, next) => {
      const ip = getClientIp(req);
      const now = Date.now();
      const timestamps = this.failures.get(ip) || [];

      // Filter timestamps within current window
      const recent = timestamps.filter((t) => now - t < this.windowMs);
      this.failures.set(ip, recent);

      if (recent.length >= this.max) {
        if (this.logger) {
          this.logger.warn("Превышен лимит попыток входа (rate limit)", {
            ip,
            attempts: recent.length,
          });
        }
        return next(
          new TooManyRequestsError(
            "Слишком много неудачных попыток входа. Подождите 15 минут перед следующей попыткой."
          )
        );
      }

      next();
    };
  }

  recordFailure(req) {
    const ip = getClientIp(req);
    const now = Date.now();
    const timestamps = this.failures.get(ip) || [];
    const recent = timestamps.filter((t) => now - t < this.windowMs);
    recent.push(now);
    this.failures.set(ip, recent);
  }

  recordSuccess(req) {
    const ip = getClientIp(req);
    this.failures.delete(ip);
  }

  cleanup() {
    const now = Date.now();
    for (const [ip, timestamps] of this.failures) {
      const recent = timestamps.filter((t) => now - t < this.windowMs);
      if (recent.length === 0) {
        this.failures.delete(ip);
      } else {
        this.failures.set(ip, recent);
      }
    }
  }

  close() {
    if (this._cleanupInterval) {
      clearInterval(this._cleanupInterval);
      this._cleanupInterval = null;
    }
  }
}

module.exports = {
  RateLimiter,
  getClientIp,
};