use 3rd party lib for word counts

Gemfile

@@ -136,6 +136,7 @@ group :worker do
   # Document understanding
   gem 'htmlentities'
   gem 'birch', git: 'https://github.com/billthompson/birch.git', branch: 'birch-ruby22'
+  gem 'word_count_analyzer'
 
   gem 'engtagger'
   gem 'ibm_watson'

Gemfile.lock

@@ -1545,6 +1545,8 @@ GEM
     websocket-driver (0.7.5)
       websocket-extensions (>= 0.1.0)
     websocket-extensions (0.1.5)
+    word_count_analyzer (1.0.1)
+      engtagger
     zeitwerk (2.4.2)
 
 PLATFORMS
@@ -1623,6 +1625,7 @@ DEPENDENCIES
   uglifier (>= 1.3.0)
   web-console
   webpacker
+  word_count_analyzer
 
 RUBY VERSION
    ruby 2.7.2p137

app/models/documents/document.rb

@@ -81,7 +81,24 @@ class Document < ApplicationRecord
   end
 
   def computed_word_count
-    (self.body || "").scan(/[\w-]+/).size
+    return 0 unless self.body && self.body.present?
+
+    WordCountAnalyzer::Counter.new(
+      ellipsis:          'no_special_treatment',
+      hyperlink:         'no_special_treatment',
+      contraction:       'count_as_multiple',
+      hyphenated_word:   'count_as_multiple',
+      date:              'count_as_one',
+      number:            'ignore',
+      numbered_list:     'ignore',
+      xhtml:             'keep',
+      forward_slash:     'count_as_multiple',
+      backslash:         'count_as_multiple',
+      dotted_line:       'count',
+      dashed_line:       'count',
+      underscore:        'count',
+      stray_punctuation: 'count'
+    ).count(self.body)
   end
 
   def reading_estimate