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Diffstat (limited to 'lib/banzai/filter/gollum_tags_filter.rb')
-rw-r--r-- | lib/banzai/filter/gollum_tags_filter.rb | 174 |
1 files changed, 174 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..f31f921903b --- /dev/null +++ b/lib/banzai/filter/gollum_tags_filter.rb @@ -0,0 +1,174 @@ +require 'banzai' +require 'html/pipeline/filter' + +module Banzai + module Filter + # HTML Filter for parsing Gollum's tags in HTML. It's only parses the + # following tags: + # + # - Link to internal pages: + # + # * [[Bug Reports]] + # * [[How to Contribute|Contributing]] + # + # - Link to external resources: + # + # * [[http://en.wikipedia.org/wiki/Git_(software)]] + # * [[Git|http://en.wikipedia.org/wiki/Git_(software)]] + # + # - Link internal images, the special attributes will be ignored: + # + # * [[images/logo.png]] + # * [[images/logo.png|alt=Logo]] + # + # - Link external images, the special attributes will be ignored: + # + # * [[http://example.com/images/logo.png]] + # * [[http://example.com/images/logo.png|alt=Logo]] + # + # - Insert a Table of Contents list: + # + # * [[_TOC_]] + # + # 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 tags content that should be parsed in HTML. + # + # Gollum's tags have been made to resemble the tags of other markups, + # especially MediaWiki. The basic syntax is: + # + # [[tag]] + # + # Some tags will accept attributes which are separated by pipe + # symbols.Some attributes must precede the tag and some must follow it: + # + # [[prefix-attribute|tag]] + # [[tag|suffix-attribute]] + # + # See https://github.com/gollum/gollum/wiki + # + # Rubular: http://rubular.com/r/7dQnE5CUCH + TAGS_PATTERN = %r{\[\[(.+?)\]\]}.freeze + + # Pattern to match allowed image extensions + ALLOWED_IMAGE_EXTENSIONS = %r{.+(jpg|png|gif|svg|bmp)\z}i.freeze + + def call + search_text_nodes(doc).each do |node| + # A Gollum ToC tag is `[[_TOC_]]`, but due to MarkdownFilter running + # before this one, it will be converted into `[[<em>TOC</em>]]`, so it + # needs special-case handling + if toc_tag?(node) + process_toc_tag(node) + else + content = node.content + + next unless content =~ TAGS_PATTERN + + html = process_tag($1) + + if html && html != node.content + node.replace(html) + end + end + end + + doc + end + + private + + # Replace an entire `[[<em>TOC</em>]]` node with the result generated by + # TableOfContentsFilter + def process_toc_tag(node) + node.parent.parent.replace(result[:toc].presence || '') + end + + # 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) + parts = tag.split('|') + + return if parts.size.zero? + + process_image_tag(parts) || process_page_link_tag(parts) + 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(parts) + content = parts[0].strip + + return unless image?(content) + + if url?(content) + path = content + elsif file = project_wiki.find_file(content) + path = ::File.join project_wiki_base_path, file.path + end + + if path + content_tag(:img, nil, src: path) + end + end + + def toc_tag?(node) + node.content == 'TOC' && + node.parent.name == 'em' && + node.parent.parent.text == '[[TOC]]' + end + + def image?(path) + path =~ ALLOWED_IMAGE_EXTENSIONS + end + + def url?(path) + path.start_with?(*%w(http https)) + 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(parts) + 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 |