FEATURE: Warn a user when they have few likes remaining

app/assets/javascripts/discourse/mixins/ajax.js

@@ -66,6 +66,10 @@ Discourse.Ajax = Em.Mixin.create({
           });
         }
 
+        if (args.returnXHR) {
+          data = { result: data, xhr };
+        }
+
         Ember.run(null, resolve, data);
       };
 

app/assets/javascripts/discourse/models/action-summary.js.es6

@@ -18,10 +18,7 @@ export default RestModel.extend({
   },
 
   togglePromise(post) {
-    if (!this.get('acted')) {
-      return this.act(post).then(() => true);
-    }
-    return this.undo(post).then(() => false);
+    return this.get('acted') ? this.undo(post) : this.act(post);
   },
 
   toggle(post) {
@@ -64,11 +61,15 @@ export default RestModel.extend({
         message: opts.message,
         take_action: opts.takeAction,
         flag_topic: this.get('flagTopic') ? true : false
-      }
-    }).then(function(result) {
+      },
+      returnXHR: true,
+    }).then(function(data) {
       if (!self.get('flagTopic')) {
-        return post.updateActionsSummary(result);
+        post.updateActionsSummary(data.result);
       }
+      const remaining = parseInt(data.xhr.getResponseHeader('Discourse-Actions-Remaining') || 0);
+      const max = parseInt(data.xhr.getResponseHeader('Discourse-Actions-Max') || 0);
+      return { acted: true, remaining, max };
     }).catch(function(error) {
       popupAjaxError(error);
       self.removeAction(post);
@@ -83,7 +84,10 @@ export default RestModel.extend({
     return Discourse.ajax("/post_actions/" + post.get('id'), {
       type: 'DELETE',
       data: { post_action_type_id: this.get('id') }
-    }).then(result => post.updateActionsSummary(result));
+    }).then(result => {
+      post.updateActionsSummary(result);
+      return { acted: false };
+    });
   },
 
   deferFlags(post) {

app/assets/javascripts/discourse/widgets/post.js.es6

@@ -423,7 +423,27 @@ export default createWidget('post', {
     const likeAction = post.get('likeAction');
 
     if (likeAction && likeAction.get('canToggle')) {
-      return likeAction.togglePromise(post);
+      return likeAction.togglePromise(post).then(result => this._warnIfClose(result));
+    }
+  },
+
+  _warnIfClose(result) {
+    if (!result || !result.acted) { return; }
+
+    const kvs = this.keyValueStore;
+    const lastWarnedLikes = kvs.get('lastWarnedLikes');
+
+    // only warn once per day
+    const yesterday = new Date().getTime() - 1000 * 60 * 60 * 24;
+    if (lastWarnedLikes && parseInt(lastWarnedLikes) > yesterday) {
+      return;
+    }
+
+    const { remaining, max } = result;
+    const threshold = Math.ceil(max * 0.1);
+    if (remaining === threshold) {
+      bootbox.alert(I18n.t('post.few_likes_left'));
+      kvs.set({ key: 'lastWarnedLikes', value: new Date().getTime() });
     }
   },
 

app/assets/javascripts/discourse/widgets/widget.js.es6

@@ -119,6 +119,7 @@ export default class Widget {
     this.currentUser = container.lookup('current-user:main');
     this.store = container.lookup('store:main');
     this.appEvents = container.lookup('app-events:main');
+    this.keyValueStore = container.lookup('key-value-store:main');
 
     if (this.name) {
       const custom = _customSettings[this.name];