add download combined pdf button

app/controllers/submissions_debug_controller.rb

@@ -16,13 +16,16 @@ class SubmissionsDebugController < ApplicationController
         render 'submit_form/show'
       end
       f.pdf do
-        if params[:audit]
-          Submissions::GenerateAuditTrail.call(@submitter.submission)
-        else
-          Submissions::GenerateResultAttachments.call(@submitter)
-        end
+        result =
+          if params[:audit]
+            Submissions::GenerateAuditTrail.call(@submitter.submission)
+          elsif params[:combined]
+            Submissions::GenerateCombinedAttachment.call(@submitter)
+          else
+            Submissions::GenerateResultAttachments.call(@submitter)
+          end
 
-        send_data ActiveStorage::Attachment.where(name: params[:audit] ? :audit_trail : :documents).last.download,
+        send_data Array.wrap(result).first.download,
                   filename: 'debug.pdf',
                   disposition: 'inline',
                   type: 'application/pdf'

app/controllers/submissions_download_controller.rb

@@ -33,7 +33,17 @@ class SubmissionsDownloadController < ApplicationController
       return head :not_found
     end
 
-    render json: build_urls(last_submitter)
+    if params[:combined]
+      url = build_combined_url(submitter)
+
+      if url
+        render json: [url]
+      else
+        head :not_found
+      end
+    else
+      render json: build_urls(last_submitter)
+    end
   end
 
   private
@@ -47,4 +57,14 @@ class SubmissionsDownloadController < ApplicationController
       ActiveStorage::Blob.proxy_url(attachment.blob, expires_at: FILES_TTL.from_now.to_i)
     end
   end
+
+  def build_combined_url(submitter)
+    return if submitter.submission.submitters.exists?(completed_at: nil)
+    return if submitter.submission.submitters.order(:completed_at).last != submitter
+
+    attachment = submitter.submission.combined_document_attachment
+    attachment ||= Submissions::GenerateCombinedAttachment.call(submitter)
+
+    ActiveStorage::Blob.proxy_url(attachment.blob, expires_at: FILES_TTL.from_now.to_i)
+  end
 end