jekyll-mentions.rb

require "jekyll"
require "html/pipeline"

module Jekyll
  class Mentions
    GITHUB_DOT_COM = "https://github.com".freeze
    BODY_START_TAG = "<body".freeze

    InvalidJekyllMentionConfig = Class.new(Jekyll::Errors::FatalException)

    class << self
      # rubocop:disable Metrics/AbcSize
      def mentionify(doc)
        return unless doc.output.include?("@")
        src = mention_base(doc.site.config)
        if doc.output.include? BODY_START_TAG
          parsed_doc    = Nokogiri::HTML::Document.parse(doc.output)
          body          = parsed_doc.at_css("body")
          body.children = filter_with_mention(src).call(body.inner_html)[:output].to_s
          doc.output    = parsed_doc.to_html
        else
          doc.output = filter_with_mention(src).call(doc.output)[:output].to_s
        end
      end

      # Public: Create or fetch the filter for the given {{src}} base URL.
      #
      # src - the base URL (e.g. https://github.com)
      #
      # Returns an HTML::Pipeline instance for the given base URL.
      def filter_with_mention(src)
        filters[src] ||= HTML::Pipeline.new([
          HTML::Pipeline::MentionFilter
        ], { :base_url => src, :username_pattern => mention_username_pattern })
      end

      def mention_username_pattern
        Regexp.new(
          HTML::Pipeline::MentionFilter::UsernamePattern.source,
          Regexp::IGNORECASE
        )
      end

      # Public: Filters hash where the key is the mention base URL.
      # Effectively a cache.
      def filters
        @filters ||= {}
      end

      # Public: Calculate the base URL to use for mentioning.
      # The custom base URL can be defined in the config as
      # jekyll-mentions.base_url or jekyll-mentions, and must
      # be a valid URL (i.e. it must include a protocol and valid domain)
      # It should _not_ have a trailing slash.
      #
      # config - the hash-like configuration of the document's site
      #
      # Returns a URL to use as the base URL for mentions.
      # Defaults to the https://github.com.
      def mention_base(config = {})
        mention_config = config["jekyll-mentions"]
        case mention_config
        when nil, NilClass
          GITHUB_DOT_COM
        when String
          mention_config.to_s
        when Hash
          mention_config.fetch("base_url", GITHUB_DOT_COM)
        else
          raise InvalidJekyllMentionConfig,
            "Your jekyll-mentions config has to either be a" \
            " string or a hash. It's a #{mention_config.class} right now."
        end
      end

      # Public: Defines the conditions for a document to be emojiable.
      #
      # doc - the Jekyll::Document or Jekyll::Page
      #
      # Returns true if the doc is written & is HTML.
      def mentionable?(doc)
        (doc.is_a?(Jekyll::Page) || doc.write?) &&
          doc.output_ext == ".html" || (doc.permalink && doc.permalink.end_with?("/"))
      end
    end
  end
end

Jekyll::Hooks.register [:pages, :documents], :post_render do |doc|
  Jekyll::Mentions.mentionify(doc) if Jekyll::Mentions.mentionable?(doc)
end