Change note length validation to ignore mention domains and URLs (#9717)

Fix #4419

app/models/account.rb

@@ -75,7 +75,7 @@ class Account < ApplicationRecord
   validates_with UniqueUsernameValidator, if: -> { local? && will_save_change_to_username? }
   validates_with UnreservedUsernameValidator, if: -> { local? && will_save_change_to_username? }
   validates :display_name, length: { maximum: 30 }, if: -> { local? && will_save_change_to_display_name? }
-  validates :note, length: { maximum: 160 }, if: -> { local? && will_save_change_to_note? }
+  validates :note, note_length: { maximum: 160 }, if: -> { local? && will_save_change_to_note? }
   validates :fields, length: { maximum: 4 }, if: -> { local? && will_save_change_to_fields? }
 
   scope :remote, -> { where.not(domain: nil) }

app/validators/note_length_validator.rb

@@ -0,0 +1,22 @@
+# frozen_string_literal: true
+
+class NoteLengthValidator < ActiveModel::EachValidator
+  def validate_each(record, attribute, value)
+    record.errors.add(attribute, I18n.t('statuses.over_character_limit', max: options[:maximum])) if too_long?(value)
+  end
+
+  private
+
+  def too_long?(value)
+    countable_text(value).mb_chars.grapheme_length > options[:maximum]
+  end
+
+  def countable_text(value)
+    return '' if value.nil?
+
+    value.dup.tap do |new_text|
+      new_text.gsub!(FetchLinkCardService::URL_PATTERN, 'x' * 23)
+      new_text.gsub!(Account::MENTION_RE, '@\2')
+    end
+  end
+end

app/validators/url_validator.rb

@@ -8,7 +8,7 @@ class UrlValidator < ActiveModel::EachValidator
   private
 
   def compliant?(url)
-    parsed_url = Addressable::URI.parse(url).normalize
-    !parsed_url.nil? && %w(http https).include?(parsed_url.scheme) && parsed_url.host
+    parsed_url = Addressable::URI.parse(url)
+    parsed_url && %w(http https).include?(parsed_url.scheme) && parsed_url.host
   end
 end