module UserNameSuggester def self.suggest(name) return unless name.present? name = parse_name_from_email(name) find_available_username_based_on(name) end private def self.parse_name_from_email(name) if name =~ User::EMAIL # When 'walter@white.com' take 'walter' name = Regexp.last_match[1] # When 'me@eviltrout.com' take 'eviltrout' name = Regexp.last_match[2] if ['i', 'me'].include?(name) end name end def self.find_available_username_based_on(name) name = rightsize_username(sanitize_username!(name)) i = 1 attempt = name until User.username_available?(attempt) suffix = i.to_s max_length = User.username_length.end - suffix.length - 1 attempt = "#{name[0..max_length]}#{suffix}" i += 1 end attempt end def self.sanitize_username!(name) name = ActiveSupport::Inflector.transliterate(name) name.gsub!(/^[^[:alnum:]]+|\W+$/, "") name.gsub!(/\W+/, "_") name.gsub!(/^\_+/, '') name end def self.rightsize_username(name) name.ljust(User.username_length.begin, '1')[0, User.username_length.end] end end