Extend static-asset cache-busting to the public layout

mtime_busted_path only ever covered the four admin-only static
files. The public layout has the identical exposure -- ccc.css,
glightbox's vendored CSS/JS, and public.js are all served straight
from public/ with no pipeline fingerprinting either -- just never
got the same treatment.

5 files changed, 32 insertions, 20 deletions

diff --git a/app/helpers/admin_helper.rb b/app/helpers/admin_helper.rb
index 6c3cbc6..2684fff 100644
--- a/app/helpers/admin_helper.rb
+++ b/app/helpers/admin_helper.rb
@@ -7,10 +7,4 @@ module AdminHelper
       link_to raw('<span class="inactive">Deutsch</span>'), url_for(params.permit(:locale, :page_path).to_h.merge('locale' => 'de'))
     end
   end
-
-  def mtime_busted_path(path)
-    file = Rails.public_path.join(path.sub(%r{\A/}, ""))
-    raise "Static asset not found for cache-busting: #{path} (looked for #{file})" unless File.exist?(file)
-    "#{path}?v=#{File.mtime(file).to_i}"
-  end
 end
diff --git a/app/helpers/application_helper.rb b/app/helpers/application_helper.rb
index 87aa82c..0d28661 100644
--- a/app/helpers/application_helper.rb
+++ b/app/helpers/application_helper.rb
@@ -15,4 +15,18 @@ module ApplicationHelper
   def resolve_kind_text(value)
     value.respond_to?(:call) ? value.call : value
   end
+
+  # Cache-busts a static file living directly under public/, outside the
+  # asset pipeline -- used by both the admin and public layouts, since
+  # neither loads its static CSS/JS through Sprockets (admin_bundle.js is
+  # the one exception; it already gets pipeline fingerprinting for free).
+  # Raises rather than silently omitting the version param: a missing
+  # file here means the page is already broken, and failing loudly beats
+  # a confusing "why is the browser still showing the old version" report
+  # days later.
+  def mtime_busted_path(path)
+    file = Rails.public_path.join(path.sub(%r{\A/}, ""))
+    raise "Static asset not found for cache-busting: #{path} (looked for #{file})" unless File.exist?(file)
+    "#{path}?v=#{File.mtime(file).to_i}"
+  end
 end
diff --git a/app/views/layouts/application.html.erb b/app/views/layouts/application.html.erb
index 57d12e6..d7681af 100644
--- a/app/views/layouts/application.html.erb
+++ b/app/views/layouts/application.html.erb
@@ -10,10 +10,10 @@
     <meta property="og:description" content="Der Chaos Computer Club ist eine galaktische Gemeinschaft von Lebewesen für Informationsfreiheit und Technikfolgenabschätzung." />
 
     <title><%= page_title %></title>
-    <link rel="stylesheet" href="/stylesheets/ccc.css">
-    <link rel="stylesheet" href="/stylesheets/glightbox.min.css">
-    <script src="/javascripts/glightbox.min.js"></script>
-    <script src="/javascripts/public.js"></script>
+    <link rel="stylesheet" href="<%= mtime_busted_path('/stylesheets/ccc.css') %>">
+    <link rel="stylesheet" href="<%= mtime_busted_path('/stylesheets/glightbox.min.css') %>">
+    <script src="<%= mtime_busted_path('/javascripts/glightbox.min.js') %>"></script>
+    <script src="<%= mtime_busted_path('/javascripts/public.js') %>"></script>
 
     <%= auto_discovery_link_tag(:atom, '/rss/updates.xml', title: "ATOM") %>
     <%= auto_discovery_link_tag(:rss,  '/rss/updates.rdf', title: "RSS") %>
diff --git a/test/models/helpers/admin_helper_test.rb b/test/models/helpers/admin_helper_test.rb
index 94e9861..23d9f40 100644
--- a/test/models/helpers/admin_helper_test.rb
+++ b/test/models/helpers/admin_helper_test.rb
@@ -1,14 +1,4 @@
 require 'test_helper'
 
 class AdminHelperTest < ActionView::TestCase
-  test "mtime_busted_path appends the file's real mtime as a query param" do
-    path = "/stylesheets/admin.css"
-    expected_mtime = File.mtime(Rails.public_path.join("stylesheets/admin.css")).to_i
-
-    assert_equal "#{path}?v=#{expected_mtime}", mtime_busted_path(path)
-  end
-
-  test "mtime_busted_path raises clearly for a missing file rather than silently omitting the version" do
-    assert_raises(RuntimeError) { mtime_busted_path("/stylesheets/does_not_exist.css") }
-  end
 end
diff --git a/test/models/helpers/application_helper_test.rb b/test/models/helpers/application_helper_test.rb
new file mode 100644
index 0000000..56096a5
--- /dev/null
+++ b/test/models/helpers/application_helper_test.rb
@@ -0,0 +1,14 @@
+require 'test_helper'
+
+class ApplicationHelperTest < ActionView::TestCase
+  test "mtime_busted_path appends the file's real mtime as a query param" do
+    path = "/stylesheets/admin.css"
+    expected_mtime = File.mtime(Rails.public_path.join("stylesheets/admin.css")).to_i
+
+    assert_equal "#{path}?v=#{expected_mtime}", mtime_busted_path(path)
+  end
+
+  test "mtime_busted_path raises clearly for a missing file rather than silently omitting the version" do
+    assert_raises(RuntimeError) { mtime_busted_path("/stylesheets/does_not_exist.css") }
+  end
+end