implement submission page

lib/templates.rb

@@ -1,4 +1,20 @@
 # frozen_string_literal: true
 
 module Templates
+  module_function
+
+  def build_field_areas_index(template)
+    hash = {}
+
+    template.fields.each do |field|
+      (field['areas'] || []).each do |area|
+        hash[area['attachment_uuid']] ||= {}
+        acc = (hash[area['attachment_uuid']][area['page']] ||= [])
+
+        acc << [area, field]
+      end
+    end
+
+    hash
+  end
 end