Count all URLs in text as 23 characters flat, do not count domain part of usernames (#4427)

* Count all URLs in text as 23 characters flat, do not count domain part of usernames

* Add new status text counting logic to web UI

app/validators/status_length_validator.rb

@@ -5,6 +5,27 @@ class StatusLengthValidator < ActiveModel::Validator
 
   def validate(status)
     return unless status.local? && !status.reblog?
-    status.errors.add(:text, I18n.t('statuses.over_character_limit', max: MAX_CHARS)) if [status.text, status.spoiler_text].join.mb_chars.grapheme_length > MAX_CHARS
+    status.errors.add(:text, I18n.t('statuses.over_character_limit', max: MAX_CHARS)) if too_long?(status)
+  end
+
+  private
+
+  def too_long?(status)
+    countable_length(status) > MAX_CHARS
+  end
+
+  def countable_length(status)
+    total_text(status).mb_chars.grapheme_length
+  end
+
+  def total_text(status)
+    [status.spoiler_text, countable_text(status)].join
+  end
+
+  def countable_text(status)
+    status.text.dup.tap do |new_text|
+      URI.extract(new_text).each { |url| new_text.gsub!(url, 'x' * 23) }
+      new_text.gsub!(Account::MENTION_RE, '@\2')
+    end
   end
 end