private _timeoutSeconds: number = 15;
private timerSubscription: Subscription;
private timer: Observable<number>;
private resetOnTrigger: boolean = false;
public timeoutExpired: Subject<number> = new Subject<number>();



constructor(
    public router: Router,
    private cd: ChangeDetectorRef) {

    this.timeoutExpired.subscribe(n => {
        alert("logout");
    });

    this.startTimer();

}

public startTimer() {
    if (this.timerSubscription) {
        this.timerSubscription.unsubscribe();
    }
  this.timer = Observable.timer(this._timeoutSeconds * 1000);
    this.timerSubscription = this.timer.subscribe(n => {
        this.timerComplete(n);
    });
}

public stopTimer() {
    console.log(this.cd + " " + "stop timer");
    this.timerSubscription.unsubscribe();
}

public resetTimer() {
    console.log(this.cd + " " + "reset timer");
    if (this.timerSubscription) {
        this.timerSubscription.unsubscribe();
    }

    this.timer = Observable.timer(this._timeoutSeconds * 1000);
    this.timerSubscription = this.timer.subscribe(n => {
        this.timerComplete(n);
    });
}

private timerComplete(n: number) {
   console.log(this.cd.detectChanges() + " " + "timer complete");
    this.timeoutExpired.next(++this._count);
    this.resetTimer();
    if (this.resetOnTrigger) {
        this.startTimer();
    }
}