import {Injectable} from '@angular/core';
import {Observable} from 'rxjs/Observable';
import {PushNotification, Permission} from './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();
        });
    }

}