_tag_links.html.haml

- submission_tag_types.each do |type|
  %li.nav-header= type.humanize
    - Submission.tag_options_for(type).each do |tag|
      = link_to_tag(tag)

routes.rb

resources :submissions do
  get 'tagged(/*tags)', to: 'submissions#index', on: :collection, :filters => /.+?/, as: :tagged
end

submission_code.rb

class SubmissionsController
  ...
    
  helper_method :tag_set
  def tag_set
    @tag_set ||= Set.new Array(params[:tags].to_s.split('/'))
  end
end
  
class Submission
  def self.tag_options_for(type)
    tags_on(type).order("LOWER(name)").pluck(:name)
  end
end

module SubmissionsHelper
  def submission_tag_types
    %w(languages frameworks tags)
  end
  
  def link_to_tag(tag)
    active = tag_set.include?(tag)
    tags   = (tag_set ^ Set.new([tag])).to_a

    content_tag(:li, class: active ? 'active' : '') do
      link_to tag, tagged_submissions_path(tags: tags)
    end
  end
end