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

1 files changed, 106 insertions, 0 deletions

diff --git a/lib/banzai/filter/gollum_tags_filter.rb b/lib/banzai/filter/gollum_tags_filter.rb
new file mode 100644
index 00000000000..f78b30bd4e9
--- /dev/null
+++ b/lib/banzai/filter/gollum_tags_filter.rb
@@ -0,0 +1,106 @@
+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