Simplify markdown preview

No need to duplicate `helpers.emojify` and manually render markdown
if we can just render a partial.

app/controllers/markdown_controller.rb

@@ -1,14 +1,5 @@
 class MarkdownController < ApplicationController
-  skip_before_action :authenticate_user!, only: [:preview]
-  respond_to :js
-
   def preview
-    if params[:source]
-      markdown_source = params[:source].to_str.gsub(/(?<=^|\s):([\w+-]+):(?=\s|$)/) do |match|
-        %(![add-emoji](https://github.githubassets.com/images/icons/emoji/#{match.to_str.tr(':', '')}.png))
-      end
-    end
-    @rendered = MarkdownHelper.render markdown_source
-    respond_with @rendered
+    @markdown_source = helpers.emojify(params[:source])
   end
 end

app/helpers/markdown_helper.rb

@@ -1,8 +1,4 @@
 module MarkdownHelper
-  def self.render(markdown_source)
-    Haml::Filters::Markdown.new.render markdown_source
-  end
-
   def mdpreview(markdown_source, lines: 3)
     markdown_source.lines.grep_v(/\[comment\]/).grep(/\S/)[0..lines - 1].join
   end

app/views/comments/_form.html.haml

@@ -13,7 +13,7 @@
     .comment-form-body
       .tab-content
         .tab-pane.active.fade.in{ role: 'tab-pane', id: "markdown-source#{id}" }
-          = f.text_area :text, :placeholder => "Your comment. You can use markdown.", :class => 'form-control input-lg markdown-source-text', :required => "required"
+          = f.text_area :text, :placeholder => "Your comment. You can use markdown.", :class => 'form-control input-lg', :required => "required"
         .tab-pane.fade{ role: 'tab-pane', id: "markdown-preview#{id}" }
           .loading-spinner
             = icon('fas', 'spinner pulse 3x')

app/views/keywords/edit.html.haml

@@ -15,7 +15,7 @@
 
     .form-group
       = f.label('Description (maximum 255 characters)')
-      = f.text_area :description, maxlength: "255", rows: 5, id: 'keyword_description', class: 'form-control input-lg markdown-source-text'
+      = f.text_area :description, maxlength: "255", rows: 5, id: 'keyword_description', class: 'form-control input-lg'
     .form-group
       = f.label('Keyword Logo (Will be resized to 150x150 Pixels)')
       = f.file_field :avatar

app/views/markdown/_preview.html.haml

@@ -0,0 +1,2 @@
+:markdown
+  #{markdown_source}

app/views/markdown/preview.js.erb

@@ -1,4 +1,4 @@
-$('#<%= params[:form_parent]%> .preview-contents').html("<%=j raw @rendered %>");
+$('#<%= params[:form_parent]%> .preview-contents').html("<%= escape_javascript(render partial: 'preview', locals: { markdown_source: @markdown_source }) %>");
 $('#<%= params[:form_parent]%> .loading-spinner').addClass('hidden');
 $('#<%= params[:form_parent]%> .preview-contents').removeClass('hidden');
 $('input[name="authenticity_token"]').val('<%= form_authenticity_token %>');

app/views/projects/_form.html.haml

@@ -28,7 +28,7 @@
           #markdown-source.tab-pane.active.fade.in{ role: 'tab-pane' }
             .form-group
               = f.text_area :description, rows: 20, id: 'project_description',
-                            class: 'form-control input-lg markdown-source-text'
+                            class: 'form-control input-lg'
           #markdown-preview.tab-pane.fade{ role: 'tab-pane' }
             .loading-spinner
               = icon('fas', 'spinner pulse 3x')

spec/controllers/markdown_controller_spec.rb

@@ -1,14 +1,13 @@
 require 'rails_helper'
 
 RSpec.describe MarkdownController, type: :controller do
-  describe 'GET #preview' do
-    it 'correctly assigns rendered html' do
-      source = '*italic*'
-
-      get :preview, xhr: true, params: { source: source }
+  render_views
 
-      expect(response).to be_successful
-      expect(assigns(:rendered)).to eq "<p><em>italic</em></p>\n"
+  describe 'GET #preview' do
+    it 'renders a markdown preview' do
+      sign_in create :user
+      get :preview, xhr: true, params: { source: '**hans**' }
+      expect(response.body).to include('$(\'# .preview-contents\').html("<p><strong>hans<\/strong><\/p>\n\n");')
     end
   end
 end