Add Banzai::Filter::GollumTagsFilter for parsing Gollum's tags in HTML

app/models/project_wiki.rb

@@ -38,6 +38,10 @@ class ProjectWiki
     [Gitlab.config.gitlab.url, "/", path_with_namespace, ".git"].join('')
   end
+  def wiki_base_path
+    ["/", @project.path_with_namespace, "/wikis"].join('')
+  end
+
   # Returns the Gollum::Wiki object.
   def wiki
     @wiki ||= begin

lib/banzai/filter/gollum_tags_filter.rb

+require 'banzai'
+require 'html/pipeline/filter'
+
+module Banzai
+  module Filter
+    # HTML Filter for parsing Gollum's tags in HTML.
+    #
+    # Based on Gollum::Filter::Tags
+    #
+    # Context options:
+    #   :project_wiki (required) - Current project wiki.
+    #
+    class GollumTagsFilter < HTML::Pipeline::Filter
+      include ActionView::Helpers::TagHelper
+
+      # Pattern to match tag contents.
+      TAGS_PATTERN = %r{(.?)\[\[(.+?)\]\]([^\[]?)}
+
+      def call
+        search_text_nodes(doc).each do |node|
+          content = node.content
+
+          next unless content.match(TAGS_PATTERN)
+
+          html = process_tag($2)
+
+          node.replace(html) if html != node.content
+        end
+
+        doc
+      end
+
+      private
+
+      # Process a single tag into its final HTML form.
+      #
+      # tag - The String tag contents (the stuff inside the double brackets).
+      #
+      # Returns the String HTML version of the tag.
+      def process_tag(tag)
+        if html = process_image_tag(tag)
+          html
+        else
+          process_page_link_tag(tag)
+        end
+      end
+
+      # Attempt to process the tag as an image tag.
+      #
+      # tag - The String tag contents (the stuff inside the double brackets).
+      #
+      # Returns the String HTML if the tag is a valid image tag or nil
+      # if it is not.
+      def process_image_tag(tag)
+        parts = tag.split('|')
+        return if parts.size.zero?
+
+        name = parts[0].strip
+
+        if file = project_wiki.find_file(name)
+          path = ::File.join project_wiki_base_path, file.path
+        elsif name =~ /^https?:\/\/.+(jpg|png|gif|svg|bmp)$/i
+          path = name
+        end
+
+        if path
+          content_tag(:img, nil, src: path)
+        end
+      end
+
+      # Attempt to process the tag as a page link tag.
+      #
+      # tag - The String tag contents (the stuff inside the double brackets).
+      #
+      # Returns the String HTML if the tag is a valid page link tag or nil
+      # if it is not.
+      def process_page_link_tag(tag)
+        parts = tag.split('|')
+        return if parts.size.zero?
+
+        if parts.size == 1
+          url = parts[0].strip
+        else
+          name, url = *parts.compact.map(&:strip)
+        end
+
+        content_tag(:a, name || url, href: url)
+      end
+
+      def project_wiki
+        context[:project_wiki]
+      end
+
+      def project_wiki_base_path
+        project_wiki && project_wiki.wiki_base_path
+      end
+
+      # Ensure that a :project_wiki key exists in context
+      #
+      # Note that while the key might exist, its value could be nil!
+      def validate
+        needs :project_wiki
+      end
+    end
+  end
+end

spec/lib/banzai/filter/gollum_tags_filter_spec.rb

+require 'spec_helper'
+
+describe Banzai::Filter::GollumTagsFilter, lib: true do
+  include FilterSpecHelper
+
+  let(:project) { create(:project) }
+  let(:user) { double }
+  let(:project_wiki) { ProjectWiki.new(project, user) }
+
+  describe 'validation' do
+    it 'ensure that a :project_wiki key exists in context' do
+      expect { filter("See [[images/image.jpg]]", {}) }.to raise_error ArgumentError, "Missing context keys for Banzai::Filter::GollumTagsFilter: :project_wiki"
+    end
+  end
+
+  context 'linking internal images' do
+    it 'creates img tag if image exists' do
+      file = Gollum::File.new(project_wiki.wiki)
+      expect(file).to receive(:path).and_return('images/image.jpg')
+      expect(project_wiki).to receive(:find_file).with('images/image.jpg').and_return(file)
+
+      tag = '[[images/image.jpg]]'
+      doc = filter("See #{tag}", project_wiki: project_wiki)
+
+      expect(doc.at_css('img')['src']).to eq "#{project_wiki.wiki_base_path}/images/image.jpg"
+    end
+
+    it 'does not creates img tag if image does not exist' do
+      expect(project_wiki).to receive(:find_file).with('images/image.jpg').and_return(nil)
+
+      tag = '[[images/image.jpg]]'
+      doc = filter("See #{tag}", project_wiki: project_wiki)
+
+      expect(doc.css('img').size).to eq 0
+    end
+  end
+
+  context 'linking external images' do
+    it 'creates img tag for valid URL' do
+      expect(project_wiki).to receive(:find_file).with('http://example.com/image.jpg').and_return(nil)
+
+      tag = '[[http://example.com/image.jpg]]'
+      doc = filter("See #{tag}", project_wiki: project_wiki)
+
+      expect(doc.at_css('img')['src']).to eq "http://example.com/image.jpg"
+    end
+
+    it 'does not creates img tag for invalid URL' do
+      expect(project_wiki).to receive(:find_file).with('http://example.com/image.pdf').and_return(nil)
+
+      tag = '[[http://example.com/image.pdf]]'
+      doc = filter("See #{tag}", project_wiki: project_wiki)
+
+      expect(doc.css('img').size).to eq 0
+    end
+  end
+
+  context 'linking external resources' do
+    it "the created link's text will be equal to the resource's text" do
+      tag = '[[http://example.com]]'
+      doc = filter("See #{tag}", project_wiki: project_wiki)
+
+      expect(doc.at_css('a').text).to eq 'http://example.com'
+      expect(doc.at_css('a')['href']).to eq 'http://example.com'
+    end
+
+    it "the created link's text will be link-text" do
+      tag = '[[link-text|http://example.com/pdfs/gollum.pdf]]'
+      doc = filter("See #{tag}", project_wiki: project_wiki)
+
+      expect(doc.at_css('a').text).to eq 'link-text'
+      expect(doc.at_css('a')['href']).to eq 'http://example.com/pdfs/gollum.pdf'
+    end
+  end
+
+  context 'linking internal resources' do
+    it "the created link's text will be equal to the resource's text" do
+      tag = '[[wiki-slug]]'
+      doc = filter("See #{tag}", project_wiki: project_wiki)
+
+      expect(doc.at_css('a').text).to eq 'wiki-slug'
+      expect(doc.at_css('a')['href']).to eq 'wiki-slug'
+    end
+
+    it "the created link's text will be link-text" do
+      tag = '[[link-text|wiki-slug]]'
+      doc = filter("See #{tag}", project_wiki: project_wiki)
+
+      expect(doc.at_css('a').text).to eq 'link-text'
+      expect(doc.at_css('a')['href']).to eq 'wiki-slug'
+    end
+  end
+end

spec/models/project_wiki_spec.rb

@@ -36,6 +36,13 @@ describe ProjectWiki, models: true do
     end
   end
+  describe "#wiki_base_path" do
+    it "returns the wiki base path" do
+      wiki_base_path = "/#{project.path_with_namespace}/wikis"
+      expect(subject.wiki_base_path).to eq(wiki_base_path)
+    end
+  end
+
   describe "#wiki" do
     it "contains a Gollum::Wiki instance" do
       expect(subject.wiki).to be_a Gollum::Wiki