Module: UserNameSuggester

Defined in:
lib/user_name_suggester.rb

Constant Summary collapse

GENERIC_NAMES = 
%w[i me info support admin webmaster hello mail office contact team]
LAST_RESORT_USERNAME = 
"user"

Class Method Summary collapse

Class Method Details

.apply_allowlist(name) ⇒ Object 



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# File 'lib/user_name_suggester.rb', line 137

def self.apply_allowlist(name)
  name.grapheme_clusters.map { |c| UsernameValidator.allowed_char?(c) ? c : "_" }.join
end

.find_available_username_based_on(name, current_username = nil) ⇒ Object 



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# File 'lib/user_name_suggester.rb', line 29

def self.find_available_username_based_on(name, current_username = nil)
  offset = nil
  i = 1

  attempt = name
  normalized_attempt = User.normalize_username(attempt)

  original_allowed_username = current_username
  current_username = User.normalize_username(current_username) if current_username

  until (normalized_attempt == current_username || User.username_available?(attempt) || i > 100)
    if offset.nil?
      normalized = User.normalize_username(name)
      similar = "#{normalized}(0|1|2|3|4|5|6|7|8|9)+"

      count = DB.query_single(<<~SQL, like: "#{normalized}%", similar: similar).first
        SELECT count(*)  FROM users
        WHERE username_lower LIKE :like AND
          username_lower SIMILAR TO :similar
      SQL

      if count > 0
        params = {
          count: count + 10,
          name: normalized,
          allowed_normalized: current_username || "",
        }

        # increasing the search space a bit to allow for some extra noise
        available = DB.query_single(<<~SQL, params).first
          WITH numbers AS (SELECT generate_series(1, :count) AS n)

          SELECT n FROM numbers
          LEFT JOIN users ON (
            username_lower = :name || n::varchar
          ) AND (
            username_lower <> :allowed_normalized
          )
          WHERE users.id IS NULL
          ORDER by n ASC
          LIMIT 1
        SQL

        # we start at 1
        offset = available.to_i - 1
        offset = 0 if offset < 0
      else
        offset = 0
      end
    end

    suffix = (i + offset).to_s

    max_length = User.username_length.end - suffix.length
    attempt = "#{truncate(name, max_length)}#{suffix}"
    normalized_attempt = User.normalize_username(attempt)
    i += 1
  end

  until normalized_attempt == current_username || User.username_available?(attempt) || i > 200
    attempt = SecureRandom.hex[1..SiteSetting.max_username_length]
    normalized_attempt = User.normalize_username(attempt)
    i += 1
  end

  if current_username == normalized_attempt
    original_allowed_username
  else
    attempt
  end
end

.fix_username(name) ⇒ Object 



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# File 'lib/user_name_suggester.rb', line 101

def self.fix_username(name)
  fixed_username = sanitize_username(name)
  if fixed_username.empty?
    fixed_username << sanitize_username(I18n.t("fallback_username"))
    fixed_username << LAST_RESORT_USERNAME if fixed_username.empty?
  end

  rightsize_username(fixed_username)
end

.parse_name_from_email(name_or_email) ⇒ Object 



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# File 'lib/user_name_suggester.rb', line 18

def self.parse_name_from_email(name_or_email)
  return name_or_email if name_or_email.to_s !~ User::EMAIL

  # When '[email protected]' take 'walter'
  name = Regexp.last_match[1]

  # When '[email protected]' take 'eviltrout'
  name = Regexp.last_match[2] if GENERIC_NAMES.include?(name)
  name
end

.rightsize_username(name) ⇒ Object 



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# File 'lib/user_name_suggester.rb', line 141

def self.rightsize_username(name)
  name = truncate(name, User.username_length.end)
  name.gsub!(UsernameValidator::INVALID_TRAILING_CHAR_PATTERN, "")

  missing_char_count = User.username_length.begin - name.grapheme_clusters.size
  name << "1" * missing_char_count if missing_char_count > 0
  name
end

.sanitize_username(name) ⇒ Object 



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# File 'lib/user_name_suggester.rb', line 111

def self.sanitize_username(name)
  name = name.to_s.dup

  if SiteSetting.unicode_usernames
    name.unicode_normalize!

    # TODO: Jan 2022, review if still needed
    # see: https://meta.discourse.org/t/unicode-username-with-as-the-final-char-leads-to-an-error-loading-profile-page/173182
    if name.include?("Σ")
      ctx = MiniRacer::Context.new
      name = ctx.eval("#{name.to_s.to_json}.toLowerCase()")
      ctx.dispose
    end
  else
    name = ActiveSupport::Inflector.transliterate(name)
  end

  name.gsub!(UsernameValidator.invalid_char_pattern, "_")
  name = apply_allowlist(name) if UsernameValidator.char_allowlist_exists?
  name.gsub!(UsernameValidator::INVALID_LEADING_CHAR_PATTERN, "")
  name.gsub!(UsernameValidator::CONFUSING_EXTENSIONS, "_")
  name.gsub!(UsernameValidator::INVALID_TRAILING_CHAR_PATTERN, "")
  name.gsub!(UsernameValidator::REPEATED_SPECIAL_CHAR_PATTERN, "_")
  name
end

.suggest(*input, current_username: nil) ⇒ Object 



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# File 'lib/user_name_suggester.rb', line 7

def self.suggest(*input, current_username: nil)
  name =
    input.find do |item|
      parsed_name = parse_name_from_email(item)
      break parsed_name if sanitize_username(parsed_name).present?
    end

  name = fix_username(name)
  find_available_username_based_on(name, current_username)
end

.truncate(name, max_grapheme_clusters) ⇒ Object 



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# File 'lib/user_name_suggester.rb', line 150

def self.truncate(name, max_grapheme_clusters)
  clusters = name.grapheme_clusters

  if clusters.size > max_grapheme_clusters
    clusters = clusters[0..max_grapheme_clusters - 1]
    name = clusters.join
  end

  while name.length > UsernameValidator::MAX_CHARS
    clusters.pop
    name = clusters.join
  end

  name
end