Add title tags to dashboard stats to show percent change from previous period

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

@@ -98,7 +98,41 @@ Discourse.Report = Discourse.Model.extend({
     default:
       return null;
     }
-  }.property('type')
+  }.property('type'),
+
+  percentChangeString: function(val1, val2) {
+    var val = ((val1 - val2) / val2) * 100;
+    if( isNaN(val) || !isFinite(val) ) {
+      return null;
+    } else if( val > 0 ) {
+      return '+' + val.toFixed(0) + '%';
+    } else {
+      return val.toFixed(0) + '%';
+    }
+  },
+
+  changeTitle: function(val1, val2, prevPeriodString) {
+    var title = '';
+    var percentChange = this.percentChangeString(val1, val2);
+    if( percentChange ) {
+      title += percentChange + ' change. ';
+    }
+    title += 'Was ' + val2 + ' ' + prevPeriodString + '.';
+    return title;
+  },
+
+  yesterdayCountTitle: function() {
+    return this.changeTitle( this.valueAt(1), this.valueAt(2),'two days ago');
+  }.property('data'),
+
+  sevenDayCountTitle: function() {
+    return this.changeTitle( this.sumDays(1,7), this.sumDays(8,14), 'two weeks ago');
+  }.property('data'),
+
+  thirtyDayCountTitle: function() {
+    return this.changeTitle( this.sumDays(1,30), this.get('prev30Days'), 'in the previous 30 day period');
+  }.property('data')
+
 });
 
 Discourse.Report.reopenClass({