Allow registering additional editor packs with stylesheets

Core editor styles are inserted as inline style tags via
`rollup-plugin-postcss` which relies on `style-inject`.

For additional editor packs in the host application, this mechanism
does not work with Shakapacker's default setup. We thus add an option
to also add links to additional stylesheet packs.

REDMINE-20374

entry_types/scrolled/app/helpers/pageflow_scrolled/packs_helper.rb

@@ -22,6 +22,13 @@ def scrolled_editor_javascript_packs_tag(entry)
       )
     end
 
+    def scrolled_editor_stylesheet_packs_tag(entry)
+      stylesheet_pack_tag(
+        *scrolled_editor_stylesheet_packs(entry),
+        media: 'all'
+      )
+    end
+
     def scrolled_frontend_packs(entry, widget_scope:)
       ['pageflow-scrolled-frontend'] +
         scrolled_additional_frontend_packs(entry, widget_scope) +
@@ -34,6 +41,10 @@ def scrolled_editor_packs(entry)
         scrolled_frontend_widget_type_packs(entry, :editor)
     end
 
+    def scrolled_editor_stylesheet_packs(entry)
+      Pageflow.config_for(entry).additional_editor_packs.stylesheet_paths
+    end
+
     private
 
     def scrolled_additional_frontend_packs(entry, widget_scope)

entry_types/scrolled/app/views/pageflow_scrolled/editor/entries/_head.html.erb

@@ -9,3 +9,4 @@
 
 <%= scrolled_webpack_public_path_script_tag %>
 <%= scrolled_editor_javascript_packs_tag(entry) %>
+<%= scrolled_editor_stylesheet_packs_tag(entry) %>

entry_types/scrolled/lib/pageflow_scrolled/additional_packs.rb

@@ -8,8 +8,8 @@ def initialize
 
     # content_element_type_names option only takes effect for frontend
     # packs.
-    def register(path, content_element_type_names: [])
-      @packs << AdditionalPack.new(path, content_element_type_names)
+    def register(path, content_element_type_names: [], stylesheet: false)
+      @packs << AdditionalPack.new(path, content_element_type_names, stylesheet)
     end
 
     # @api private
@@ -24,6 +24,11 @@ def paths
       @packs.map(&:path)
     end
 
+    # @api private
+    def stylesheet_paths
+      @packs.select(&:stylesheet).map(&:path)
+    end
+
     # @api private
     def paths_for_content_element_types(type_names)
       @packs.reject { |pack|
@@ -33,6 +38,6 @@ def paths_for_content_element_types(type_names)
     end
 
     # @api private
-    AdditionalPack = Struct.new(:path, :content_element_type_names)
+    AdditionalPack = Struct.new(:path, :content_element_type_names, :stylesheet)
   end
 end

entry_types/scrolled/spec/helpers/pageflow_scrolled/packs_helper_spec.rb

@@ -247,5 +247,36 @@ module PageflowScrolled
         expect(result).to include('pageflow-scrolled/widgets/customNavigation')
       end
     end
+
+    describe 'scrolled_editor_stylesheet_packs' do
+      it 'empty by default' do
+        entry = create(:published_entry, type_name: 'scrolled')
+
+        result = helper.scrolled_editor_stylesheet_packs(entry)
+
+        expect(result).to eq([])
+      end
+
+      it 'includes additional editor packs in editor with stylesheet option' do
+        pageflow_configure do |config|
+          config.for_entry_type(PageflowScrolled.entry_type) do |entry_type_config|
+            entry_type_config.additional_editor_packs.register(
+              'pageflow-scrolled/only-js'
+            )
+
+            entry_type_config.additional_editor_packs.register(
+              'pageflow-scrolled/extra-editor',
+              stylesheet: true
+            )
+          end
+        end
+
+        entry = create(:published_entry, type_name: 'scrolled')
+
+        result = helper.scrolled_editor_stylesheet_packs(entry)
+
+        expect(result).to eq(['pageflow-scrolled/extra-editor'])
+      end
+    end
   end
 end