gistfile1.rb

require 'rubygems'
require 'bundler/setup'

require 'css_parser'

class String
  CSS_CLASS_REGEX = /\.[\w-]+/ix
  CSS_ID_REGEX = /\#[\w-]+/ix

  def css_classes
    scan(CSS_CLASS_REGEX)
  end

  def css_identifiers
    scan(CSS_ID_REGEX)
  end

  def css_classes_and_identifiers
    scan(Regexp.union(CSS_CLASS_REGEX, CSS_ID_REGEX))
  end
end

class UnusedCssFinder
  PROJECT_PATH = '/home/vagrant/shopify'
  attr_accessor :classes, :identifiers

  def initialize
    @parser = CssParser::Parser.new
  end

  def load_css_from_uri(address)
    @parser.load_uri!(address)

    selectors = []
    @parser.each_selector { |s| selectors << s }

    # weirdo_selectors = selectors.map do |s|
    #   s if s.css_classes_and_identifiers.empty?
    # end.compact

    @identifiers = selectors.map(&:css_identifiers).flatten.uniq
    @classes = selectors.map(&:css_classes).flatten.uniq
  end

  def find_in_project(css_thing, path)
    css_thing = css_thing[1..-1] # Remove prevailing . or # to just have the class name

    cmd = `ack-grep --match "[ \\"\\']#{css_thing}[ \\"\\']" --type-set=coffeescript=.coffee --coffee --ruby --js --coffeescript #{path}/app/ #{path}/vendor/`

    if cmd.empty?
      css_thing
    else
      nil
    end
  end

  def report
    puts "These are suspected unused CSS classes/identifiers:"

    @suspected_unused_css_things = []
    [@classes + @identifiers].flatten.each do |css_thing|
      if find_in_project(css_thing, PROJECT_PATH)
        @suspected_unused_css_things << css_thing
        puts css_thing
      end
    end
  end

  def git_into_it
    git_logs_path = "unused_css_git_logs"
    `mkdir #{git_logs_path}`
    puts "Ok, I’m generating git log things on all of this business and putting them in #{git_logs_path}"
    puts "Please note that this is going to take like #{@suspected_unused_css_things} minutes to run."
    @suspected_unused_css_things.each do |css_thing|
      `git log -S#{css_thing} --patch --max-count=5 -- . ':(exclude)*.css' ':(exclude)*.scss' > #{PROJECT_PATH}/#{git_logs_path}/#{css_thing}.diff`
    end

    puts "Ok! Done. Look in #{git_logs_path} for diffs to help you investigate."
  end
end

unused_css_finder = UnusedCssFinder.new

puts "Ok! Looking for unused CSS in #{UnusedCssFinder::PROJECT_PATH}"
css_uri = 'http://cdn.myshopify.io/s/assets/admin/style-e0b8e5ba14d67e7e2135f5450301ef3c.css'

begin
  unused_css_finder.load_css_from_uri(css_uri)
rescue CssParser::RemoteFileError
  puts "It looks like #{css_uri} isn’t loading. Exiting."
  exit
end

puts "Loaded #{css_uri}"
puts "Identifiers: #{unused_css_finder.identifiers.size}"
puts "Classes: #{unused_css_finder.classes.size}"
puts

unused_css_finder.report

# Don’t use this for now since it takes forever
# Just use it on css things that aren’t obviously used by generated code or not
# unused_css_finder.git_into_it