feat(messaging): AngularFireMessaing

[davideast]

AngularFireMessaging

This is a WIP, but here is the current API surface.

class AngularFireMessaging {
  messaging: FirebaseMessaging;
  requestPermission: Observable<void>;
  getToken: Observable<string>;
  tokenChanges: Observable<string>;
  messages: Observable<{}>;
  requestToken: Observable<string>;
  deleteToken: (token: string) => Observable<any>;
}

[jamesdaniels]

We should make this a single IMO

[jamesdaniels]

Err, that's a Promise hance a single... nevermind.

[jamesdaniels]

So now that I'm playing with this I'm not sure I like this API. I think I'd prefer:

this.tokenChanges => from(this.messaging.onTokenRefresh);

this.token => this.getToken.pipe(concat(this.tokenChanges))

Thoughts?

[jamesdaniels]

Hmmm... not sure about this API either, how about

this.deleteToken = this.getToken.pipe(
  mergeMap(t => t ? this.messaging.deleteToken(t) : empty() )
)

[jamesdaniels]

Why not inline?

[jamesdaniels]

We should catch the requestPermission exception and complete with null