refactor: use enumeration for the type of an origin

src/core/Thing.ts

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2018 StApps
+ * Copyright (C) 2018, 2019 StApps
  * This program is free software: you can redistribute it and/or modify it
  * under the terms of the GNU General Public License as published by the Free
  * Software Foundation, version 3.
@@ -96,7 +96,13 @@ export interface SCThing {
   url?: string;
 }
 
-export type SCThingOriginType = 'remote' | 'user';
+/**
+ * Possible types of an origin
+ */
+export enum SCThingOriginType {
+  Remote = 'remote',
+  User = 'user',
+}
 
 /**
  * Origin of a thing
@@ -149,7 +155,7 @@ export interface SCThingRemoteOrigin extends SCThingOrigin {
   /**
    * Type of the origin
    */
-  type: 'remote';
+  type: SCThingOriginType.Remote;
 
   /**
    * Main URL of the origin
@@ -174,7 +180,7 @@ export interface SCThingUserOrigin extends SCThingOrigin {
   /**
    * Type of the origin
    */
-  type: 'user';
+  type: SCThingOriginType.User;
 
   /**
    * When the saved thing was last updated with the latest state (e.g. from the backend)

src/core/things/Favorite.ts

@@ -41,6 +41,9 @@ export type SCFavoriteDataTypes = SCAcademicEventWithoutReferences
  * @validatable
  */
 export interface SCFavorite extends SCSaveableThing<SCFavoriteDataTypes> {
+  /**
+   * Type of a favorite
+   */
   type: SCThingType.Favorite;
 }