import { Fingerprinter } from "./fingerprinter.js";
import type { FingerprintAttributes } from "./fingerprinter.js";

const NAVIGATION_API_SUPPORTED = !!window.navigation;

class ActivityTracker {
  static get instance() {
    return (this.#instance ??= new this());
  }

  static #instance: ActivityTracker | undefined;

  private constructor() {}

  #activity: ActivityEvent[] = [];

  #connected = false;
  #fingerprintAttributes?: FingerprintAttributes;

  isImpersonated = false;

  #boundNavigationHandler?: (event: any) => void;

  async connect(init: ActivityTrackerInit) {
    this.isImpersonated = init.isImpersonated;

    if (!this.#fingerprintAttributes) {
      this.#fingerprintAttributes = await Fingerprinter.getAttributes({
        cookieDomain: init.cookieDomain,
        storageTtlDays: 365,
      });
    }

    if (!this.#connected) {
      // add initial navigation event
      this.#activity.push(this.#buildNavigationEvent());
      this.#configureNavigationWatchers();
    }

    this.#connected = true;
  }

  disconnect() {
    this.#activity = [];
    this.#connected = false;
    if (!this.#boundNavigationHandler) {
      return;
    }

    if (NAVIGATION_API_SUPPORTED) {
      window.navigation.removeEventListener("currententrychange", this.#boundNavigationHandler);
    } else {
      window.removeEventListener("zapiPushState", this.#boundNavigationHandler);
      window.removeEventListener("zapiReplaceState", this.#boundNavigationHandler);
    }
  }

  async retrieveActivity() {
    return new Promise<ActivityEvent[]>((resolve) => {
      const result = [...this.#activity];
      this.#activity = [];
      resolve(result);
    });
  }

  #configureNavigationWatchers() {
    if (NAVIGATION_API_SUPPORTED) {
      this.#boundNavigationHandler = this.#onNavigate.bind(this);
      window.navigation.addEventListener("currententrychange", this.#boundNavigationHandler);
    } else {
      window.addEventListener("zapiPushState", this.#onNavigate.bind(this));
      window.addEventListener("zapiReplaceState", this.#onNavigate.bind(this));
    }
  }

  #onNavigate() {
    this.#activity.push(this.#buildNavigationEvent());
  }

  #buildNavigationEvent() {
    return {
      type: "Navigation",
      location: window.location.href,
      eventDateTime: new Date(),
      isImpersonated: this.isImpersonated,
      // bf = browserFingerprint
      bf: this.#fingerprintAttributes?.storage,
      // sw = screenWidth
      sw: this.#fingerprintAttributes?.screenWidth,
      // sh = screenHeight
      sh: this.#fingerprintAttributes?.screenHeight,
      // cf = canvasFingerprint
      cf: this.#fingerprintAttributes?.canvas,
      // tz = timeZone
      tz: this.#fingerprintAttributes?.timeZone,
      // dnt = doNotTrack
      dnt: this.#fingerprintAttributes?.doNotTrack,
      // gpc = globalPrivacyControl
      gpc: this.#fingerprintAttributes?.gpc,
      // prm = prefersReducedMotion
      prm: this.#fingerprintAttributes?.prefersReducedMotion,
      // pcs = prefersColorScheme
      pcs: this.#fingerprintAttributes?.prefersColorScheme,
    };
  }
}

const activityTracker = ActivityTracker.instance;

export { activityTracker as ActivityTracker };

type ActivityTrackerInit = {
  isImpersonated: boolean;
  cookieDomain?: string | null | undefined;
};

type ActivityEvent = {
  type: string;
  location: string;
  eventDateTime: Date;
  isImpersonated: boolean;
};