check for duplicates and display notification banner on the index page where appropriate

tests to cover the desired behaviour

app/controllers/lettings_logs_controller.rb

@@ -1,4 +1,6 @@
 class LettingsLogsController < LogsController
+  include DuplicateLogsHelper
+
   rescue_from ActiveRecord::RecordNotFound, with: :render_not_found
 
   before_action :find_resource, only: %i[update show]
@@ -11,20 +13,20 @@ class LettingsLogsController < LogsController
   before_action :redirect_if_bulk_upload_resolved, only: [:index]
 
   def index
-    respond_to do |format|
-      format.html do
-        all_logs = current_user.lettings_logs.visible
-        unpaginated_filtered_logs = filter_manager.filtered_logs(all_logs, search_term, session_filters)
-
-        @delete_logs_path = delete_logs_lettings_logs_path(search: search_term)
-        @pagy, @logs = pagy(unpaginated_filtered_logs)
-        @searched = search_term.presence
-        @total_count = all_logs.size
-        @unresolved_count = all_logs.unresolved.created_by(current_user).count
-        @filter_type = "lettings_logs"
-        render "logs/index"
-      end
+    if current_user.data_provider? && (@duplicates = duplicates_for_user(current_user))
+      @duplicate_sets_count = @duplicates[:lettings].count + @duplicates[:sales].count
     end
+
+    all_logs = current_user.lettings_logs.visible
+    unpaginated_filtered_logs = filter_manager.filtered_logs(all_logs, search_term, session_filters)
+
+    @delete_logs_path = delete_logs_lettings_logs_path(search: search_term)
+    @pagy, @logs = pagy(unpaginated_filtered_logs)
+    @searched = search_term.presence
+    @total_count = all_logs.size
+    @unresolved_count = all_logs.unresolved.created_by(current_user).count
+    @filter_type = "lettings_logs"
+    render "logs/index"
   end
 
   def create

app/views/logs/index.html.erb

@@ -8,6 +8,12 @@
   organisation: @organisation,
 ) %>
 
+<% if @duplicates %>
+  <%= govuk_notification_banner(title_text: "Important", text: govuk_link_to("Review logs", href: "#")) do |banner|
+    banner.with_heading(text: I18n.t("notification.duplicate_sets", count: @duplicate_sets_count))
+  end %>
+<% end %>
+
 <% if current_page?(controller: 'lettings_logs', action: 'index') %>
   <% if @unresolved_count > 0 %>
     <%= govuk_notification_banner(

config/locales/en.yml

@@ -189,6 +189,9 @@ en:
       other: "%{log_ids} have been deleted."
     duplicate_logs:
         deduplication_success_banner: "%{log_link} is no longer a duplicate and has been removed from the list.<p class=\"govuk-body govuk-!-margin-top-4\">You changed the %{changed_question_label}.</p>"
+    duplicate_sets:
+      one: "There is %{count} set of duplicate logs"
+      other: "There are %{count} sets of duplicate logs"
 
   validations:
     organisation:

spec/requests/lettings_logs_controller_spec.rb

@@ -238,8 +238,6 @@ RSpec.describe LettingsLogsController, type: :request do
       let(:headers) { { "Accept" => "text/html" } }
 
       context "when you visit the index page" do
-        let(:user) { FactoryBot.create(:user, :support) }
-
         before do
           allow(user).to receive(:need_two_factor_authentication?).and_return(false)
           sign_in user
@@ -308,6 +306,13 @@ RSpec.describe LettingsLogsController, type: :request do
           expect(page).to have_link("Download (CSV, codes only)", href: "/lettings-logs/csv-download?codes_only=true")
         end
 
+        it "does not show a notification banner even if there are duplicate logs for this user" do
+          allow_any_instance_of(DuplicateLogsHelper).to receive(:duplicates_for_user).and_return({ lettings: [[1, 2]], sales: [] }) # rubocop:disable RSpec/AnyInstance
+          get lettings_logs_path
+          expect(page).not_to have_content "duplicate logs"
+          expect(page).not_to have_link "Review logs"
+        end
+
         context "when there are no logs in the database" do
           before do
             LettingsLog.destroy_all
@@ -615,6 +620,12 @@ RSpec.describe LettingsLogsController, type: :request do
           expect(page).not_to have_link("Download (CSV, codes only)")
         end
 
+        it "does not show a notification banner even if there are duplicate logs for this user" do
+          get lettings_logs_path
+          expect(page).not_to have_content "duplicate logs"
+          expect(page).not_to have_link "Review logs"
+        end
+
         context "when using a search query" do
           let(:logs) { FactoryBot.create_list(:lettings_log, 3, :completed, owning_organisation: user.organisation, created_by: user) }
           let(:log_to_search) { FactoryBot.create(:lettings_log, :completed, owning_organisation: user.organisation, created_by: user) }
@@ -871,6 +882,38 @@ RSpec.describe LettingsLogsController, type: :request do
             end
           end
         end
+
+        context "and there are duplicate logs for this user" do
+          let(:duplicates) { { lettings:, sales: } }
+          let(:lettings) { [[1, 2]] }
+          let(:sales) { [] }
+
+          before do
+            allow_any_instance_of(DuplicateLogsHelper).to receive(:duplicates_for_user).and_return duplicates # rubocop:disable RSpec/AnyInstance
+          end
+
+          it "displays a notification banner with a link to review logs" do
+            get lettings_logs_path
+            expect(page).to have_content "duplicate logs"
+            expect(page).to have_link "Review logs" # add an href when routing done
+          end
+
+          context "when there is one set of duplicates" do
+            it "displays the correct copy in the banner" do
+              get lettings_logs_path
+              expect(page).to have_content "There is 1 set of duplicate logs"
+            end
+          end
+
+          context "when there are multiple sets of duplicates" do
+            let(:sales) { [[3, 4]] }
+
+            it "displays the correct copy in the banner" do
+              get lettings_logs_path
+              expect(page).to have_content "There are 2 sets of duplicate logs"
+            end
+          end
+        end
       end
     end