import { Injectable } from '@angular/core';
import { Observable } from 'rxjs';
import { PushNotification, Permission } from '../interfaces/push-notification.type';

declare const Notification: any;

@Injectable()
export class PushNotificationsService {

    permission: Permission;

    constructor() {
        this.permission = this.isSupported() ? Notification.permission : 'denied';
    }

    requestPermission() {
        if ('Notification' in window) {
            Notification.requestPermission((status: any) => this.permission = status);
        }
    }

    isSupported() {
        return 'Notification' in window;
    }

    create(title: string, options?: PushNotification): any {

        return new Observable((obs: any) => {

            if (!('Notification' in window)) {
                obs.error('Notifications are not available in this environment');
                obs.complete();
            }

            if (this.permission !== 'granted') {
                obs.error(`The user hasn't granted you permission to send push notifications`);
                obs.complete();
            }

            const n = new Notification(title, options);

            n.onshow = (e: any) => obs.next({ notification: n, event: e });
            n.onclick = (e: any) => obs.next({ notification: n, event: e });
            n.onerror = (e: any) => obs.error({ notification: n, event: e });
            n.onclose = () => obs.complete();
        });
    }

}