Use Active Storage to render custom images

Just like we did with regular attachments, we're moving the logic to
generate URLs out of the model.

Note we're changing the `image_path_for` helper method in order to
return a `polymorphic_path` because sometimes it's used in combination
with `favicon_link_tag`, and `favicon_link_tag` doesn't automatically
generate a polymorphic URL when given an `ActiveStorage::Attachment`
record.

app/helpers/application_helper.rb

@@ -49,7 +49,13 @@ module ApplicationHelper
   end
 
   def image_path_for(filename)
-    SiteCustomization::Image.image_path_for(filename) || filename
+    image = SiteCustomization::Image.image_for(filename)
+
+    if image
+      polymorphic_path(image)
+    else
+      filename
+    end
   end
 
   def content_block(name, locale = I18n.locale)

app/models/site_customization/image.rb

@@ -23,11 +23,10 @@ class SiteCustomization::Image < ApplicationRecord
     end
   end
 
-  def self.image_path_for(filename)
+  def self.image_for(filename)
     image_name = filename.split(".").first
 
-    imageable = find_by(name: image_name)
-    imageable.present? && imageable.image.exists? ? imageable.image.url : nil
+    find_by(name: image_name)&.persisted_image
   end
 
   def required_width
@@ -38,6 +37,14 @@ class SiteCustomization::Image < ApplicationRecord
     VALID_IMAGES[name]&.second
   end
 
+  def persisted_image
+    storage_image if persisted_attachment?
+  end
+
+  def persisted_attachment?
+    storage_image.attachment&.persisted?
+  end
+
   private
 
     def check_image

app/views/admin/site_customization/images/index.html.erb

@@ -16,12 +16,12 @@
         <td class="small-12 medium-8">
           <%= form_for([:admin, image], html: { id: "edit_#{dom_id(image)}" }) do |f| %>
             <div class="small-12 medium-6 large-6 column">
-              <%= image_tag image.image.url if image.image.exists? %>
+              <%= image_tag image.storage_image if image.persisted_attachment? %>
               <%= f.file_field :image, label: false %>
             </div>
             <div class="small-12 medium-6 large-6 column">
               <%= f.submit(t("admin.site_customization.images.index.update"), class: "button hollow") %>
-              <%= link_to t("admin.site_customization.images.index.delete"), admin_site_customization_image_path(image), method: :delete, class: "button hollow alert" if image.image.exists? %>
+              <%= link_to t("admin.site_customization.images.index.delete"), admin_site_customization_image_path(image), method: :delete, class: "button hollow alert" if image.persisted_attachment? %>
             </div>
           <% end %>
         </td>

spec/system/admin/site_customization/images_spec.rb

@@ -60,6 +60,17 @@ describe "Admin custom images", :admin do
     end
   end
 
+  scenario "Custom apple touch icon is replaced on front views" do
+    create(:site_customization_image,
+           name: "apple-touch-icon-200",
+           image: File.new("spec/fixtures/files/apple-touch-icon-custom-200.png"))
+
+    visit root_path
+
+    expect(page).not_to have_css("link[href*='apple-touch-icon-200']", visible: :all)
+    expect(page).to have_css("link[href*='apple-touch-icon-custom-200']", visible: :hidden)
+  end
+
   scenario "Image is replaced on admin newsletters" do
     newsletter = create(:newsletter, segment_recipient: "all_users")