FIX: do not display used categories as selectable in categories notifications preferences

app/assets/javascripts/discourse/controllers/preferences/categories.js.es6

@@ -1,5 +1,6 @@
 import PreferencesTabController from "discourse/mixins/preferences-tab-controller";
 import { popupAjaxError } from 'discourse/lib/ajax-error';
+import { default as computed } from "ember-addons/ember-computed-decorators";
 
 export default Ember.Controller.extend(PreferencesTabController, {
   saveAttrNames: [
@@ -9,6 +10,11 @@ export default Ember.Controller.extend(PreferencesTabController, {
     'watched_first_post_category_ids'
   ],
 
+  @computed("model.watchedCategories", "model.watchedFirstPostCategories", "model.trackedCategories", "model.mutedCategories")
+  selectedCategories(watched, watchedFirst, tracked, muted) {
+    return [].concat(watched, watchedFirst, tracked, muted);
+  },
+
   canSave: function() {
     return this.get('currentUser.id') === this.get('model.id') ||
       this.get('currentUser.admin');

app/assets/javascripts/discourse/controllers/preferences/notifications.js.es6

@@ -1,5 +1,4 @@
 import PreferencesTabController from "discourse/mixins/preferences-tab-controller";
-import { default as computed } from "ember-addons/ember-computed-decorators";
 import { NotificationLevels } from 'discourse/lib/notification-levels';
 import { popupAjaxError } from 'discourse/lib/ajax-error';
 
@@ -14,11 +13,6 @@ export default Ember.Controller.extend(PreferencesTabController, {
     'allow_private_messages',
   ],
 
-  @computed("model.watchedCategories", "model.trackedCategories", "model.mutedCategories")
-  selectedCategories(watched, tracked, muted) {
-    return [].concat(watched, tracked, muted);
-  },
-
   likeNotificationFrequencies: [{ name: I18n.t('user.like_notification_frequency.always'), value: 0 },
                       { name: I18n.t('user.like_notification_frequency.first_time_and_daily'), value: 1 },
                       { name: I18n.t('user.like_notification_frequency.first_time'), value: 2 },

app/assets/javascripts/discourse/templates/preferences/categories.hbs

@@ -1,5 +1,4 @@
 <div class="control-group category-notifications">
-
   <label class="control-label">{{i18n 'user.categories_settings'}}</label>
 
   <div class="controls category-controls">
@@ -22,7 +21,7 @@
 
   <div class="controls category-controls">
     <label>{{d-icon "d-watching-first"}} {{i18n 'user.watched_first_post_categories'}}</label>
-    {{category-selector categories=model.watchedFirstPostCategories}}
+    {{category-selector categories=model.watchedFirstPostCategories blacklist=selectedCategories}}
   </div>
   <div class="instructions">{{i18n 'user.watched_first_post_categories_instructions'}}</div>
 

app/assets/javascripts/select-kit/components/category-selector.js.es6

@@ -35,6 +35,9 @@ export default MultiSelectComponent.extend({
 
   computeContent() {
     const blacklist = Ember.makeArray(this.get("blacklist"));
-    return Category.list().filter(category => !blacklist.includes(category));
+    return Category.list().filter(category => {
+      return this.get("computedValues").includes(category.id) ||
+             !blacklist.includes(category);
+    });
   }
 });