Dynamic back button

app/javascript/styles/_task-list.scss

@@ -81,7 +81,7 @@
   }
 }
 
-// turbo-frame {
-//   display: block;
-//   border: 1px solid blue
-// }
+turbo-frame {
+  display: block;
+  border: 1px solid blue
+}

app/models/form.rb

@@ -36,4 +36,8 @@ class Form < ApplicationRecord
   def self.next_question(previous_question)
     Form::QUESTIONS[previous_question]
   end
+
+  def self.previous_question(current_question)
+    Hash[QUESTIONS.to_a.map(&:reverse)][current_question]
+  end
 end

app/views/form/questions/previous_housing_situation.html.erb

@@ -24,6 +24,11 @@
     OpenStruct.new(id: 22, name: "Lifetime PRP General Needs tenancy"),
 ] %>
 
+<% previous_question = Form.previous_question("previous_housing_situation") %>
+<%= govuk_back_link href: "/case_logs/#{case_log_id}/#{previous_question}" do %>
+  Back
+<% end %>
+
 <%= turbo_frame_tag "case_log_form", target: "_top" do %>
   <%= form_with action: '/case_logs', method: "next_question", builder: GOVUKDesignSystemFormBuilder::FormBuilder do |f| %>
     <%= f.govuk_collection_radio_buttons :previous_housing_situation, situations, :id, :name, legend: { text: "What was the tenant’s housing situation immediately before this letting?", size: "l" } %>

app/views/form/questions/tenant_age.html.erb

@@ -1,7 +1,9 @@
-<%= turbo_frame_tag "case_log_form", target: "_top" do %>
-  <%= govuk_back_link GovukComponent::BackLinkComponent.new href: 'tenant_code' do %>
-    back
+<% previous_question = Form.previous_question("tenant_age") %>
+<%= govuk_back_link href: "/case_logs/#{case_log_id}/#{previous_question}" do %>
+  Back
 <% end %>
+
+<%= turbo_frame_tag "case_log_form", target: "_top" do %>
   <%= form_with action: '/case_logs', method: "next_question", builder: GOVUKDesignSystemFormBuilder::FormBuilder do |f| %>
     <%= f.govuk_number_field :tenant_age,
             hint: { text: "More detail" },

app/views/form/questions/tenant_code.html.erb

@@ -1,7 +1,9 @@
-<%= turbo_frame_tag "case_log_form", target: "_top" do %>
-  <%= govuk_back_link href: "/case_logs/#{case_log_id}" do %>
+<% previous_question = Form.previous_question("tenant_code") %>
+<%= govuk_back_link href: "/case_logs/#{case_log_id}/#{previous_question}" do %>
   Back
 <% end %>
+
+<%= turbo_frame_tag "case_log_form", target: "_top" do %>
   <%= form_with action: '/case_logs', method: "next_question", builder: GOVUKDesignSystemFormBuilder::FormBuilder do |f| %>
      <%= f.govuk_text_field :tenant_code,
           hint: { text: "More detail" },

app/views/form/questions/tenant_gender.html.erb

@@ -5,6 +5,11 @@
     OpenStruct.new(id: 3, name: "Prefer not to say")
 ] %>
 
+<% previous_question = Form.previous_question("tenant_gender") %>
+<%= govuk_back_link href: "/case_logs/#{case_log_id}/#{previous_question}" do %>
+  Back
+<% end %>
+
 <%= turbo_frame_tag "case_log_form", target: "_top" do %>
   <%= form_with action: '/case_logs', method: "next_question", builder: GOVUKDesignSystemFormBuilder::FormBuilder do |f| %>
     <%= f.govuk_collection_radio_buttons :tenant_gender, genders, :id, :name, legend: { text: "Which of these best describes the tenant's gender identity?", size: "l" } %>

spec/models/form_spec.rb

@@ -14,4 +14,20 @@ RSpec.describe Form, type: :model do
       expect(Form.first_question_for_subsection(subsection)).to eq("tenant_code")
     end
   end
+
+  describe ".previous_question" do
+    context "given a question in the middle of a subsection" do
+      let(:current_question) { "tenant_age" }
+      it "returns the previous question given the current" do
+        expect(Form.previous_question(current_question)).to eq("tenant_code")
+      end
+    end
+
+    context "given the first question in a subsection" do
+      let(:current_question) { "tenant_code" }
+      it "returns empty string" do
+        expect(Form.previous_question(current_question)).to be_nil
+      end
+    end
+  end
 end