mokum-urlifier.rb

  def self.replace_urls (text)
    rx = /(https?:\/\/\p{^Space}+)/
    components = text.split(rx).map do |str|
      if rx =~ str
        chopped = ""
        extra_url = ""
        str.gsub!(/\p{Punct}+\z/) do |trailing|
          if !trailing.blank? && trailing[0] == ')' && /[(]/ =~ str
            extra_url += ")"
            trailing.slice!(0)
          end

          if !trailing.blank? && trailing[0] == '/'
            extra_url += "/"
            trailing.slice!(0)
          end

          chopped = trailing

          ""
        end
        str += extra_url

        uri = Addressable::URI.parse(str)
        if uri
          short_url = ActionController::Base.helpers.truncate str, length: 64, omission: "..."
          begin
            canonical = Addressable::URI.normalized_encode(uri)
          rescue
            canonical = uri
          end
            
          if /\Ahttps?:\/\/mokum.ru\// =~ str
            "<a href='#{canonical}'>#{short_url}</a>" + chopped
          else
            "<a href='#{canonical}' target='_blank'>#{short_url}</a>" + chopped
          end
        else
          str + chopped
        end
      else
        folded_text = CGI.escapeHTML(str)

        folded_text.gsub!(/@[a-z0-9][a-z0-9_-]+[a-z0-9]\b/) do |username|
          username.slice!(0)

          feed = User.find_by(name: username) || Group.find_by(name: username)
          if feed
            "<a href='/#{username}/'>@#{username}</a>"
          else
            "@#{username}"
          end
        end
        folded_text
      end
    end

    components.join("")
  end