Rack::SpellCheck

spell_check.rb

=begin

 Rack::SpellCheck - Spell check your HTML pages with Aspell, Nokogiri, and Rack.

 This probably should be loaded in an initializer like so:
 
     if Rails.env.development?                                                                                                                                                                   
       SpintoApp::Application.config.middleware.use Rack::SpellCheck
     end

 And you should add Nokogiri and Raspell to your Gemfile:

     group :development do
       gem 'nokogiri'
       gem 'raspell'
     end

 It creates log entries like:

     Started GET "/" for 127.0.0.1 at 2012-02-29 15:05:34 -0500
       Processing by Main::DashboardController#show as HTML
    Rendered main/dashboard/show.erb within layouts/marketing (5.0ms)
    Rendered layouts/_header.erb (31.3ms)
    Rendered layouts/_footer.erb (0.6ms)
    Completed 200 OK in 81ms (Views: 80.5ms)
    SpellCheck [workflow]: work flow, work-flow, workfare, workforce, workable, forkful
    SpellCheck [walkthrough]: walk through, walk-through, breakthrough, walkabout, Valkyrie, Walker
    SpellCheck [frontmatter]: front matter, front-matter, frontward, antimatter, fronted, frontier
    SpellCheck [subdomain]: sub domain, sub-domain, subhuman, subliming, subsuming, sideman
    SpellCheck [dns]: Dons, dens, dins, dons, duns, DNA
    SpellChecked in 0.244784 seconds.

=end

class Rack::SpellCheck

  def initialize app
    @app = app
    @speller = Aspell.new("en_US")
    @speller.suggestion_mode = Aspell::NORMAL
    @misspellings = {}
    @whitelist = %w{
      Matt Beale Spinto Spinto's spinto
      matt beale www
      css js scss CSS SCSS SASS CoffeeScript coffeescript
      li td GitHub pre YAML CNAME
      yoursubdomain
    }
  end

  def call env
    @app.call(env).tap do |response|
      begin
        if response[1]["Content-Type"] =~ /html/
          spell_check response[2].body
        end
      rescue StandardError => e 
        Rails.logger.warn "SpellCheck failed: #{e.message}"
      end
    end
  end
  
  def spell_check body 
    started_at = Time.now
    dom = (if body =~ /<body/
      Nokogiri::HTML.parse( body )
    else
      Nokogiri::HTML.fragment( body )
    end)
    reported_words = []
    dom.xpath('//*').each do |node|
      next unless node.text.present?
      node.text.
        # Strip out URLs.
        gsub(%r{[a-zA-Z0-9\.:/]+\.(?:co|net|org)[a-zA-Z0-9\.:/?&%]+}, '').
        # For each word.
        scan(%r{[A-Za-z\u2019'&;]+}) do |word|
        # Change HTML escaped and UTF-8 apostrophes to single quotes.
        word.gsub!(%r{\u2019|&rsquo;}, "'")
        key = word.downcase
        next if @whitelist.include?(word) || reported_words.include?(key)
        reported_words << key
        check_word word
      end
    end 
    Rails.logger.info "SpellChecked in #{(Time.now-started_at).seconds} seconds."
  end

  def check_word word
    key = word.downcase
    if @misspellings.has_key?(key) && @misspellings[key][:suggestions]
      log_misspelling word, @misspellings[key][:suggestions]
    else
      if @speller.check(word)
        @misspellings[key] = { checked: true }
      else
        @misspellings[key] = { checked: true, suggestions: @speller.suggest(word) }
        check_word word
      end
    end
  end

  def log_misspelling word, suggestions
    Rails.logger.warn "SpellCheck [#{word}]: #{suggestions[0..5].join ', '}"
  end

end