UserAgent.ts

import { IncomingHttpHeaders } from "http";

// types
import { RequestExtended } from "../types/Request";
import { TypeUserAgentBrowser, TypeUserAgentDevice, TypeUserAgentSystem } from "../types/Utils";

/**
 * Class for detecting information about the browser and device from the User-Agent header.
 *
 * @class
 */
class UserAgent {
  req: RequestExtended;
  headers: IncomingHttpHeaders;
  accept: IncomingHttpHeaders["accept"];
  userAgent: IncomingHttpHeaders["user-agent"];

  /**
   * Creates an instance of the `UserAgent` class.
   * @param {RequestExtended} req - The request object with headers.
   */
  constructor(req: RequestExtended) {
    this.req = req;
    this.headers = req.headers;
    this.accept = req.headers?.["accept"]?.toLocaleLowerCase();
    this.userAgent = req.headers?.["user-agent"]?.toLocaleLowerCase();
    return;
  }

  /**
   * Detects the browser based on the `User-Agent` header of the request.
   *
   * @returns {TypeUserAgentBrowser} The name of the browser (e.g., "chrome", "firefox", "opera", etc.)
   */
  browser(): TypeUserAgentBrowser {
    let currentBrowser: TypeUserAgentBrowser = "unknown";
    if (!this.userAgent) {
      return currentBrowser;
    }
    if (/opera|opr/i.test(this.userAgent)) {
      currentBrowser = "opera";
    } else if (/edge|edg/i.test(this.userAgent)) {
      currentBrowser = "edge";
    } else if (/chrome/i.test(this.userAgent)) {
      currentBrowser = "chrome";
    } else if (/firefox/i.test(this.userAgent)) {
      currentBrowser = "firefox";
    } else if (/safari/i.test(this.userAgent)) {
      currentBrowser = "safari";
    } else if (/msie|trident/i.test(this.userAgent)) {
      currentBrowser = "internet explorer";
    }
    return currentBrowser;
  }

  /**
   * Detects the type of device based on the `User-Agent` header and `Accept` header of the request.
   *
   * @returns {TypeUserAgentDevice} The type of the device ("mobile", "api", "desktop").
   */
  device(): TypeUserAgentDevice {
    let currentDevice: TypeUserAgentDevice = "desktop";
    if (this.userAgent && /mobile|iphone|android|ipad/.test(this.userAgent)) {
      currentDevice = "mobile";
    }
    if (this.userAgent && /postmanruntime/.test(this.userAgent)) {
      currentDevice = "api";
    }
    if (this.userAgent && /curl/.test(this.userAgent)) {
      currentDevice = "api";
    }
    if ((this.accept && this.accept.includes("application/json")) || !this.userAgent) {
      currentDevice = "api";
    }
    return currentDevice;
  }

  /**
   * Detects the operating system from the user-agent string.
   *
   * @returns {TypeUserAgentSystem} The name of the detected operating system.
   * Possible return values: 'windows', 'macos', 'android', 'ios', 'linux', or 'unknown' if no match is found.
   */
  system(): TypeUserAgentSystem {
    let currentSystem: TypeUserAgentSystem = "unknown";
    if (!this.userAgent) {
      return currentSystem;
    }
    if (/windows nt/.test(this.userAgent)) {
      currentSystem = "windows";
    } else if (/iphone|ipad|ipod/.test(this.userAgent)) {
      currentSystem = "ios";
    } else if (/mac os x|macintosh/.test(this.userAgent)) {
      currentSystem = "macos";
    } else if (/android/.test(this.userAgent)) {
      currentSystem = "android";
    } else if (/linux/.test(this.userAgent)) {
      currentSystem = "linux";
    }
    return currentSystem;
  }

  /**
   * Retrieves the client's IP address from the request headers.
   * It first checks the 'x-forwarded-for' header, which may contain a list of IPs if the request passed through proxies.
   * If unavailable, it falls back to the remote address from the socket.
   *
   * @returns {string} The client's IP address as a string.
   */
  ip(): string {
    const forwardedFor = this.headers?.["x-forwarded-for"];
    if (typeof forwardedFor === "string") {
      return forwardedFor.split(",")[0].trim();
    }
    return this.req.socket?.remoteAddress || "";
  }
}

export default UserAgent;