Show supporter level ticket URL on the registration page

app/helpers/registration_helper.rb

@@ -0,0 +1,14 @@
+module RegistrationHelper
+  def generate_supporter_level_js(conference)
+    str = ""
+    conference.supporter_levels.map do |t|
+      next if t.url.empty?
+
+      str += "if ($('#registration_supporter_registration_attributes_supporter_level_id option:selected').text() == '#{t.title}') {\n"
+      str += "console.log('#{t.title}');\n"
+      str += "str = 'If you have a confirmation or registration code, enter it here.  Otherwise, you can purchase a <i>#{t.title}</i> ticket <a href=\"#{t.url}\" target=_new>here</a>, if you need to.';\n"
+      str += "}\n\n"
+    end.join("\n")
+    str
+  end
+end

app/views/conference_registration/register.html.haml

@@ -27,10 +27,19 @@
         - if @conference.use_supporter_levels?
           = f.semantic_fields_for :supporter_registration do |reg|
             = reg.input :supporter_level, :as => :select, :collection => @conference.supporter_levels
-            = reg.input :code, :hint => "If you have a confirmation or registration code, enter it here."
+            = reg.input :code, :label => "Confirmation or registration code (if applicable)"
+            %span#supporter-link.help-block
         - if @registered
           = f.action :submit, :button_html => { :value => "Update Registration", :class => "btn btn-primary" }
           = link_to "Unregister", register_conference_path(@conference.short_title),:method => :delete, :class => "btn btn-danger",
                       :confirm => "Are you sure you want to unregister?"
         - else
           = f.action :submit, :button_html => { :value => "Register", :class => "btn btn-primary" }
+
+:javascript
+    $("#registration_supporter_registration_attributes_supporter_level_id").change(function () {
+      var str = "";
+      #{generate_supporter_level_js @conference}
+      $("#supporter-link").html(str);
+    })
+    .trigger('change');