Adding configurable e-mail blacklist

app/lib/email_validator.rb

@@ -0,0 +1,18 @@
+# frozen_string_literal: true
+
+class EmailValidator < ActiveModel::EachValidator
+  def validate_each(record, attribute, value)
+    return if Rails.configuration.x.email_domains_blacklist.empty?
+
+    record.errors.add(attribute, I18n.t('users.invalid_email')) if blocked_email?(value)
+  end
+
+  private
+
+  def blocked_email?(value)
+    domains = Rails.configuration.x.email_domains_blacklist.gsub('.', '\.')
+    regexp  = Regexp.new("@(.+\\.)?(#{domains})", true)
+
+    value =~ regexp
+  end
+end

app/models/user.rb

@@ -8,6 +8,7 @@ class User < ApplicationRecord
 
   validates :account, presence: true
   validates :locale, inclusion: I18n.available_locales.map(&:to_s), unless: 'locale.nil?'
+  validates :email, email: true
 
   scope :prolific, -> { joins('inner join statuses on statuses.account_id = users.account_id').select('users.*, count(statuses.id) as statuses_count').group('users.id').order('statuses_count desc') }
   scope :recent,   -> { order('id desc') }