calculate the number of days it takes until the stock might be gone

app/mailers/spree/stock_mailer.rb

@@ -42,8 +42,10 @@ module Spree
         else
             name = "Sku " + var.sku
         end
+	days = var.count_on_hand / mean
 
-        {'weighted_mean' => mean, 'variant' => var, 'product' => var.product, 'name' => name}
+        {'weighted_mean' => mean, 'days' => days, 'variant' => var,
+            'product' => var.product, 'name' => name}
     end
 
     def generate_forecast()

app/views/spree/stock_mailer/stock_report_email.text.erb

@@ -5,7 +5,7 @@ will run low.
 
 Estimates:
 <% @forecast.each do |dict| %>
-<%= dict['name'] %> => <%= dict['weighted_mean'].round(2) %> days until sold out.
+<%= dict['name'] %> => <%= dict['days'].round(2) %> days until sold out.
 <% end %>