Fix LaTeX formatting for AsciiDoc wiki

lib/banzai/filter/ascii_doc_post_processing_filter.rb

+module Banzai
+  module Filter
+    class AsciiDocPostProcessingFilter < HTML::Pipeline::Filter
+      def call
+        doc.search('[data-math-style]').each do |node|
+          node.set_attribute('class', 'code math js-render-math')
+        end
+
+        doc
+      end
+    end
+  end
+end

lib/banzai/filter/sanitization_filter.rb

@@ -31,6 +31,10 @@ module Banzai
         # Allow span elements
         whitelist[:elements].push('span')
 
+        # Allow data-math-style attribute in order to support LaTeX formatting
+        whitelist[:attributes]['code'] = %w(data-math-style)
+        whitelist[:attributes]['pre'] = %w(data-math-style)
+
         # Allow html5 details/summary elements
         whitelist[:elements].push('details')
         whitelist[:elements].push('summary')

lib/banzai/pipeline/ascii_doc_pipeline.rb

+module Banzai
+  module Pipeline
+    class AsciiDocPipeline < BasePipeline
+      def self.filters
+        FilterArray[
+          Filter::SanitizationFilter,
+          Filter::ExternalLinkFilter,
+          Filter::PlantumlFilter,
+          Filter::AsciiDocPostProcessingFilter
+        ]
+      end
+    end
+  end
+end

lib/gitlab/asciidoc.rb

@@ -20,21 +20,20 @@ module Gitlab
                         backend: :gitlab_html5,
                         attributes: DEFAULT_ADOC_ATTRS }
 
-      context[:pipeline] = :markup
+      context[:pipeline] = :ascii_doc
 
       plantuml_setup
 
       html = ::Asciidoctor.convert(input, asciidoc_opts)
       html = Banzai.render(html, context)
-
       html.html_safe
     end
 
     def self.plantuml_setup
       Asciidoctor::PlantUml.configure do |conf|
-        conf.url = ApplicationSetting.current.plantuml_url
-        conf.svg_enable = ApplicationSetting.current.plantuml_enabled
-        conf.png_enable = ApplicationSetting.current.plantuml_enabled
+        conf.url = current_application_settings.plantuml_url
+        conf.svg_enable = current_application_settings.plantuml_enabled
+        conf.png_enable = current_application_settings.plantuml_enabled
         conf.txt_enable = false
       end
     end
@@ -47,13 +46,13 @@ module Gitlab
       def stem(node)
         return super unless node.style.to_sym == :latexmath
 
-        %(<pre#{id_attribute(node)} class="code math js-render-math #{node.role}" data-math-style="display"><code>#{node.content}</code></pre>)
+        %(<pre#{id_attribute(node)} data-math-style="display"><code>#{node.content}</code></pre>)
       end
 
       def inline_quoted(node)
         return super unless node.type.to_sym == :latexmath
 
-        %(<code#{id_attribute(node)} class="code math js-render-math #{node.role}" data-math-style="inline">#{node.text}</code>)
+        %(<code#{id_attribute(node)} data-math-style="inline">#{node.text}</code>)
       end
 
       private

spec/features/projects/wiki/user_creates_wiki_page_spec.rb

@@ -28,6 +28,40 @@ feature 'Projects > Wiki > User creates wiki page', js: true, feature: true do
         expect(page).to have_content("Last edited by #{user.name}")
         expect(page).to have_content('My awesome wiki!')
       end
+
+      scenario 'creates ASCII wiki with LaTeX blocks' do
+        stub_application_setting(plantuml_url: 'http://localhost', plantuml_enabled: true)
+
+        ascii_content = <<~MD
+          :stem: latexmath
+
+          [stem]
+          ++++
+          \sqrt{4} = 2
+          ++++
+
+          another part
+
+          [latexmath]
+          ++++
+          \beta_x \gamma
+          ++++
+
+          stem:[2+2] is 4
+        MD
+
+        find('#wiki_format option[value=asciidoc]').select_option
+        fill_in :wiki_content, with: ascii_content
+
+        page.within '.wiki-form' do
+          click_button 'Create page'
+        end
+
+        page.within '.wiki' do
+          expect(page).to have_selector('.katex', count: 3)
+          expect(page).to have_content('2+2 is 4')
+        end
+      end
     end
 
     context 'when wiki is not empty' do

spec/lib/banzai/filter/ascii_doc_post_processing_filter_spec.rb

+require 'spec_helper'
+
+describe Banzai::Filter::AsciiDocPostProcessingFilter, lib: true do
+  include FilterSpecHelper
+
+  it "adds class for elements with data-math-style" do
+    result = filter('<pre data-math-style="inline">some code</pre><div data-math>and</div>').to_html
+    expect(result).to eq('<pre data-math-style="inline" class="code math js-render-math">some code</pre><div data-math>and</div>')
+  end
+
+  it "keeps content when no data-math-style found" do
+    result = filter('<pre>some code</pre><div data-math>and</div>').to_html
+    expect(result).to eq('<pre>some code</pre><div data-math>and</div>')
+  end
+end

spec/lib/banzai/filter/sanitization_filter_spec.rb

@@ -97,6 +97,22 @@ describe Banzai::Filter::SanitizationFilter, lib: true do
       expect(filter(act).to_html).to eq exp
     end
 
+    it 'allows `data-math-style` attribute on `code` and `pre` elements' do
+      html = <<-HTML
+      <pre class="code" data-math-style="inline">something</pre>
+      <code class="code" data-math-style="inline">something</code>
+      <div class="code" data-math-style="inline">something</div>
+      HTML
+
+      output = <<-HTML
+      <pre data-math-style="inline">something</pre>
+      <code data-math-style="inline">something</code>
+      <div>something</div>
+      HTML
+
+      expect(filter(html).to_html).to eq(output)
+    end
+
     it 'removes `rel` attribute from `a` elements' do
       act = %q{<a href="#" rel="nofollow">Link</a>}
       exp = %q{<a href="#">Link</a>}

spec/lib/gitlab/asciidoc_spec.rb

@@ -70,6 +70,31 @@ module Gitlab
           expect(output).to include('rel="nofollow noreferrer noopener"')
         end
       end
+
+      context 'LaTex code' do
+        it 'adds class js-render-math to the output' do
+          input = <<~MD
+            :stem: latexmath
+
+            [stem]
+            ++++
+            \sqrt{4} = 2
+            ++++
+
+            another part
+
+            [latexmath]
+            ++++
+            \beta_x \gamma
+            ++++
+
+            stem:[2+2] is 4
+            MD
+
+          expect(render(input, context)).to include('<pre data-math-style="display" class="code math js-render-math"><code>eta_x gamma</code></pre>')
+          expect(render(input, context)).to include('<p><code data-math-style="inline" class="code math js-render-math">2+2</code> is 4</p>')
+        end
+      end
     end
 
     def render(*args)