FIX: better handling of no prev30Days (#6301)

app/assets/javascripts/admin/models/report.js.es6

@@ -439,7 +439,7 @@ const Report = Discourse.Model.extend({
       case "high-trending-down":
         return higherIsBetter ? "angle-double-down" : "angle-double-up";
       default:
-        return null;
+        return "minus";
     }
   }
 });

app/assets/javascripts/admin/templates/components/admin-report-counters.hbs

@@ -16,5 +16,9 @@
 </div>
 
 <div class="cell value thirty-days-count {{model.thirtyDaysTrend}}" title={{model.thirtyDaysCountTitle}}>
-  {{number model.lastThirtyDaysCount}} {{d-icon model.thirtyDaysTrendIcon}}
+  {{number model.lastThirtyDaysCount}}
+
+  {{#if model.prev30Days}}
+    {{d-icon model.thirtyDaysTrendIcon}}
+  {{/if}}
 </div>

app/assets/stylesheets/common/admin/admin_report.scss

@@ -59,6 +59,9 @@
 
     &.no-change {
       color: $primary-medium;
+      i {
+        display: none;
+      }
     }
 
     .value {

app/assets/stylesheets/common/admin/admin_report_counters.scss

@@ -34,6 +34,13 @@
         }
       }
 
+      &.no-change {
+        i {
+          color: $primary-medium;
+          font-size: $font-down-3;
+        }
+      }
+
       &.high-trending-up,
       &.trending-up {
         i {

app/models/report.rb

@@ -217,8 +217,9 @@ class Report
     report.icon = 'user'
 
     basic_report_about report, UserVisit, :by_day, report.start_date, report.end_date, report.group_id
-
     add_counts report, UserVisit, 'visited_at'
+
+    report.prev30Days = UserVisit.where(mobile: true).where("visited_at >= ? and visited_at < ?", report.start_date - 30.days, report.start_date).count
   end
 
   def self.report_mobile_visits(report)