Use current, previous and next forms in sales log model

app/models/sales_log.rb

@@ -21,9 +21,10 @@ class SalesLog < Log
   end
 
   def form_name
-    return unless saledate
+    return unless startdate
 
-    "#{collection_start_year}_#{collection_start_year + 1}_sales"
+    form_mappings = { 0 => "current_sales", 1 => "previous_sales", -1 => "next_sales" }
+    form_mappings[FormHandler.instance.current_collection_start_year - collection_start_year] if collection_start_year.present?
   end
 
   def form

spec/models/sales_log_spec.rb

@@ -34,7 +34,7 @@ RSpec.describe SalesLog, type: :model do
     it "has returns the correct form based on the start date" do
       expect(sales_log.form_name).to be_nil
       expect(sales_log.form).to be_a(Form)
-      expect(sales_log_2.form_name).to eq("2022_2023_sales")
+      expect(sales_log_2.form_name).to eq("current_sales")
       expect(sales_log_2.form).to be_a(Form)
     end
   end