Add variable definitions as the first row of csv downloads

app/services/csv/lettings_log_csv_service.rb

@@ -5,10 +5,17 @@ module Csv
       @export_type = export_type
       @year = year
       @attributes = lettings_log_attributes
+      @definitions = lettings_log_definitions
     end
 
     def prepare_csv(logs)
       CSV.generate(headers: true) do |csv|
+        if @year >= 2023
+          csv << @attributes.map do |attribute|
+            record = @definitions.find { |r| r.variable == attribute.downcase }
+            record&.tap { |r| r.update!(last_accessed: Time.zone.now) }&.definition
+          end
+        end
         csv << @attributes
 
         logs.find_each do |log|
@@ -258,6 +265,16 @@ module Csv
       @user.support? ? final_attributes : final_attributes - SUPPORT_ONLY_ATTRIBUTES - soft_validations_attributes
     end
 
+    def lettings_log_definitions
+      CsvVariableDefinition.lettings.group_by { |record| [record.variable, record.definition] }
+                           .map do |_, options|
+        exact_match = options.find { |definition| definition.year == @year }
+        next exact_match if exact_match
+
+        options.max_by(&:year)
+      end
+    end
+
     def insert_derived_and_related_attributes(ordered_questions)
       ordered_questions.flat_map do |question|
         if question.type == "checkbox"

app/services/csv/sales_log_csv_service.rb

@@ -5,11 +5,19 @@ module Csv
       @export_type = export_type
       @year = year
       @attributes = sales_log_attributes
+      @definitions = sales_log_definitions
     end
 
     def prepare_csv(logs)
       CSV.generate(headers: true) do |csv|
-        csv << formatted_attribute_headers
+        formatted_attributes = formatted_attribute_headers
+        if @year >= 2023
+          csv << formatted_attributes.map do |attribute|
+            record = @definitions.find { |r| r.variable == attribute.downcase }
+            record&.tap { |r| r.update!(last_accessed: Time.zone.now) }&.definition
+          end
+        end
+        csv << formatted_attributes
 
         logs.find_each do |log|
           csv << @attributes.map { |attribute| value(attribute, log) }
@@ -161,6 +169,16 @@ module Csv
       @user.support? ? final_attributes : final_attributes - SUPPORT_ONLY_ATTRIBUTES
     end
 
+    def sales_log_definitions
+      CsvVariableDefinition.sales.group_by { |record| [record.variable, record.definition] }
+                           .map do |_, options|
+        exact_match = options.find { |definition| definition.year == @year }
+        next exact_match if exact_match
+
+        options.max_by(&:year)
+      end
+    end
+
     def insert_derived_and_related_attributes(ordered_questions)
       ordered_questions.flat_map do |question|
         if question.type == "checkbox"