FEATURE: add a message explaining the user why they're being redirected to the top page

app/assets/javascripts/discourse/controllers/top_controller.js

@@ -0,0 +1,35 @@
+/**
+  Controller of the top page
+
+  @class TopController
+  @extends Discourse.ObjectController
+  @namespace Discourse
+  @module Discourse
+**/
+Discourse.TopController = Discourse.ObjectController.extend({
+
+  redirectedToTopPageReason: function() {
+    // no need for a reason if the default homepage is "top"
+    if (Discourse.Utilities.defaultHomepage() === "top") { return null; }
+    // check if the user is authenticated
+    if (Discourse.User.current()) {
+      if (Discourse.User.currentProp("trust_level") === 0) {
+        return I18n.t("filters.top.redirect_reasons.new_user");
+      } else if (!Discourse.User.currentProp("hasBeenSeenInTheLastMonth")) {
+        return I18n.t("filters.top.redirect_reasons.not_seen_in_a_month");
+      }
+    }
+    // no reason detected
+    return null;
+  }.property(),
+
+  showThisYear: function() {
+    if (Discourse.User.current()) {
+      return !Discourse.User.currentProp("hasBeenSeenInTheLastMonth");
+    } else {
+      return true;
+    }
+  }.property(),
+
+
+});

app/assets/javascripts/discourse/templates/top.js.handlebars

@@ -1,5 +1,12 @@
-<h2>{{i18n filters.top.this_year}}</h2>
-{{basic-topic-list topicList=content.yearly}}
+{{#if redirectedToTopPageReason}}
+  <div class="alert alert-info">
+    {{redirectedToTopPageReason}}
+  </div>
+{{/if}}
+{{#if showThisYear}}
+  <h2>{{i18n filters.top.this_year}}</h2>
+  {{basic-topic-list topicList=content.yearly}}
+{{/if}}
 <h2>{{i18n filters.top.this_month}}</h2>
 {{basic-topic-list topicList=content.monthly}}
 <h2>{{i18n filters.top.this_week}}</h2>

config/locales/client.en.yml

@@ -1117,6 +1117,9 @@ en:
         this_month: "This month"
         this_week: "This week"
         today: "Today"
+        redirect_reasons:
+          new_user: "You are a new user. This will be your homepage for a while. If you don't know where to start, here's a summary of the best topics."
+          not_seen_in_a_month: "We have not seen you in more than a month. Here's a summary of the best topics since you were away."
 
     browser_update: 'Unfortunately, <a href="http://www.discourse.org/faq/#browser">your browser is too old to work on this Discourse forum</a>. Please <a href="http://browsehappy.com">upgrade your browser</a>.'