Don't add ActionDispatch::Static middleware continued (#1892)

* Don't add ActionDispatch::Static middleware

In the case that rails do not serve static files is not
necessary to add ActionDispatch::Static middleware. Making
possible to deploy ViewComponenets previews on a production
environment where Nginx or Apache is managing the static files.

* Apply suggestions from code review

Co-authored-by: Joel Hawksley <joelhawksley@github.com>

* Update index.md

* add: prism cdn if no asset precompiler found

* edit: change prism cdn version to 1.28

* Update app/helpers/preview_helper.rb

Co-authored-by: Cameron Dutro <camertron@gmail.com>

* Update app/helpers/preview_helper.rb

Co-authored-by: Cameron Dutro <camertron@gmail.com>

* Update app/helpers/preview_helper.rb

Co-authored-by: Cameron Dutro <camertron@gmail.com>

* Update app/helpers/preview_helper.rb

Co-authored-by: Cameron Dutro <camertron@gmail.com>

* Update lib/view_component/engine.rb

Co-authored-by: Cameron Dutro <camertron@gmail.com>

* edit: fix brocken tests

* edit: refactor tests

* edit: fix for rails > 6.1

* edit: fix lint issues

* Update lib/view_component/engine.rb

Co-authored-by: Hans Lemuet <Spone@users.noreply.github.com>

---------

Co-authored-by: Daniel Gonzalez <danigonza86@gmail.com>
Co-authored-by: Joel Hawksley <joelhawksley@github.com>
Co-authored-by: Cameron Dutro <camertron@gmail.com>
Co-authored-by: Hans Lemuet <Spone@users.noreply.github.com>

app/helpers/preview_helper.rb

@@ -1,6 +1,8 @@
 # frozen_string_literal: true
 
 module PreviewHelper
+  include ActionView::Helpers::AssetUrlHelper if Rails.version.to_f < 6.1
+
   AVAILABLE_PRISM_LANGUAGES = %w[ruby erb haml]
   FALLBACK_LANGUAGE = "ruby"
 
@@ -10,6 +12,14 @@ def preview_source
     render "preview_source"
   end
 
+  def prism_css_source_url
+    serve_static_preview_assets? ? asset_path("prism.css", skip_pipeline: true) : "https://cdn.jsdelivr.net/npm/prismjs@1.28.0/themes/prism.min.css"
+  end
+
+  def prism_js_source_url
+    serve_static_preview_assets? ? asset_path("prism.min.js", skip_pipeline: true) : "https://cdn.jsdelivr.net/npm/prismjs@1.28.0/prism.min.js"
+  end
+
   def find_template_data(lookup_context:, template_identifier:)
     template = lookup_context.find_template(template_identifier)
 
@@ -62,4 +72,8 @@ def prism_language_name_by_template_path(template_file_path:)
 
     language
   end
+
+  def serve_static_preview_assets?
+    ViewComponent::Base.config.show_previews && Rails.application.config.public_file_server.enabled
+  end
 end

app/views/view_components/_preview_source.html.erb

@@ -1,4 +1,4 @@
-<link href="<%= asset_path('prism.css', skip_pipeline: true) %>" media="screen" rel="stylesheet" type="text/css">
+<link href="<%= prism_css_source_url %>" media="screen" rel="stylesheet" type="text/css">
 <div class="view-component-source-example">
   <h2>Source:</h2>
   <pre class="source">
@@ -14,4 +14,4 @@
     <% end %>
   </pre>
 </div>
-<script type="text/javascript" src="<%= asset_path('prism.min.js', skip_pipeline: true) %>"></script>
+<script type="text/javascript" src="<%= prism_js_source_url %>"></script>

docs/CHANGELOG.md

@@ -10,6 +10,11 @@ nav_order: 5
 
 ## main
 
+* Don't add ActionDispatch::Static middleware unless `public_file_server.enabled`.
+
+    *Daniel Gonzalez*
+    *Reegan Viljoen*
+
 * Resolve an issue where slots starting with `call` would cause a `NameError`
 
     *Blake Williams*

docs/index.md

@@ -204,6 +204,7 @@ ViewComponent is built by over a hundred members of the community, including:
 <img src="https://avatars.githubusercontent.com/xronos-i-am?s=64" alt="xronos-i-am" width="32" />
 <img src="https://avatars.githubusercontent.com/yykamei?s=64" alt="yykamei" width="32" />
 <img src="https://avatars.githubusercontent.com/matheuspolicamilo?s=64" alt="matheuspolicamilo" width="32" />
+<img src="https://avatars.githubusercontent.com/danigonza?s=64" alt="danigonza" width="32" />
 <img src="https://avatars.githubusercontent.com/erinnachen?s=64" alt="erinnachen" width="32" />
 <img src="https://avatars.githubusercontent.com/ihollander?s=64" alt="ihollander" width="32" />
 <img src="https://avatars.githubusercontent.com/svetlins?s=64" alt="svetlins" width="32" />

lib/view_component/engine.rb

@@ -110,11 +110,15 @@ class Engine < Rails::Engine # :nodoc:
     end
 
     initializer "static assets" do |app|
-      if app.config.view_component.show_previews
+      if serve_static_preview_assets?(app.config)
         app.middleware.use(::ActionDispatch::Static, "#{root}/app/assets/vendor")
       end
     end
 
+    def serve_static_preview_assets?(app_config)
+      app_config.view_component.show_previews && app_config.public_file_server.enabled
+    end
+
     initializer "compiler mode" do |_app|
       ViewComponent::Compiler.mode = if Rails.env.development? || Rails.env.test?
         ViewComponent::Compiler::DEVELOPMENT_MODE

test/sandbox/test/preview_helper_test.rb

@@ -155,5 +155,37 @@ def test_raises_with_conflict_in_template_resolution
         assert_equal("Found multiple templates for #{template_identifier}.", exception.message)
       end
     end
+
+    def test_prism_css_source_url_with_asset_pipeline
+      Rails.application.config.public_file_server.stub(:enabled, true) do
+        if Rails.version.to_f >= 6.1
+          assert_equal "/assets/prism.css", PreviewHelper.prism_css_source_url
+        else
+          assert_equal "/prism.css", PreviewHelper.prism_css_source_url
+        end
+      end
+    end
+
+    def test_prism_css_source_url_with_no_asset_pipeline
+      Rails.application.config.public_file_server.stub(:enabled, false) do
+        assert_equal "https://cdn.jsdelivr.net/npm/prismjs@1.28.0/themes/prism.min.css", PreviewHelper.prism_css_source_url
+      end
+    end
+
+    def test_prism_js_source_with_asset_pipeline
+      Rails.application.config.public_file_server.stub(:enabled, true) do
+        if Rails.version.to_f >= 6.1
+          assert_equal "/assets/prism.min.js", PreviewHelper.prism_js_source_url
+        else
+          assert_equal "/prism.min.js", PreviewHelper.prism_js_source_url
+        end
+      end
+    end
+
+    def test_prism_js_source_url_with_no_asset_pipeline
+      Rails.application.config.public_file_server.stub(:enabled, false) do
+        assert_equal "https://cdn.jsdelivr.net/npm/prismjs@1.28.0/prism.min.js", PreviewHelper.prism_js_source_url
+      end
+    end
   end
 end

test/view_component/engine_test.rb

@@ -0,0 +1,10 @@
+# frozen_string_literal: true
+
+require "test_helper"
+
+class ViewComponent::EngineTest < ActionDispatch::IntegrationTest
+  def test_serve_static_previews?
+    app.config.public_file_server.enabled = false
+    refute ViewComponent::Engine.instance.serve_static_preview_assets?(app.config)
+  end
+end