module UserNameSuggester def self.suggest(name, allow_username = nil) return unless name.present? name = parse_name_from_email(name) find_available_username_based_on(name, allow_username) end 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, allow_username = nil) name = fix_username(name) i = 1 attempt = name until attempt == allow_username || 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.fix_username(name) rightsize_username(sanitize_username(name)) end def self.sanitize_username(name) name = ActiveSupport::Inflector.transliterate(name) # 1. replace characters that aren't allowed with '_' name.gsub!(UsernameValidator::CONFUSING_EXTENSIONS, "_") name.gsub!(/[^\w.-]/, "_") # 2. removes unallowed leading characters name.gsub!(/^\W+/, "") # 3. removes unallowed trailing characters name.gsub!(/[^A-Za-z0-9]+$/, "") # 4. unify special characters name.gsub!(/[-_.]{2,}/, "_") name end def self.rightsize_username(name) name.ljust(User.username_length.begin, '1')[0, User.username_length.end] end end