import { fromEvent, merge, interval, Subject, NEVER, Observable } from 'rxjs';
import { throttle, filter, switchMap } from 'rxjs/operators';

export class MwInactivityService {
  private inactivityInterval = 1000;
  private pauser = new Subject<boolean>();

  getCallback(inactivityTimeoutInSeconds: number): Observable<number> {
    console.log('Inactivity after ' + inactivityTimeoutInSeconds);
    return this.pauser.pipe(
      switchMap((paused) =>
        paused ? NEVER : this.source(inactivityTimeoutInSeconds)
      )
    );
  }

  start(): void {
    this.pauser.next(false);
  }

  stop(): void {
    this.pauser.next(true);
  }

  private source(inactivityTimeoutInSeconds: number): Observable<number> {
    const mouseMove = fromEvent(document, 'mousemove');
    const mouseDown = fromEvent(document, 'mousedown');
    const touchMove = fromEvent(document, 'touchmove');
    const touchEnd = fromEvent(document, 'touchend');
    const keypress = fromEvent(document, 'keypress');
    const wheel = fromEvent(document, 'wheel');

    const mergedEvents = merge(
      wheel,
      mouseMove,
      mouseDown,
      touchMove,
      touchEnd,
      keypress
    ).pipe(throttle((t) => interval(this.inactivityInterval)));

    return mergedEvents.pipe(
      switchMap((t) => interval(1000)),
      filter((t) => t === inactivityTimeoutInSeconds)
    );
  }
}