# frozen_string_literal: true class LanguageDetector include Singleton WORDS_THRESHOLD = 4 RELIABLE_CHARACTERS_RE = /[\p{Hebrew}\p{Arabic}\p{Syriac}\p{Thaana}\p{Nko}\p{Han}\p{Katakana}\p{Hiragana}\p{Hangul}]+/m def initialize @identifier = CLD3::NNetLanguageIdentifier.new(1, 2048) end def detect(text, account) input_text = prepare_text(text) return if input_text.blank? detect_language_code(input_text) || default_locale(account) end def language_names @language_names = CLD3::TaskContextParams::LANGUAGE_NAMES.map { |name| iso6391(name.to_s).to_sym }.uniq end private def prepare_text(text) simplify_text(text).strip end def unreliable_input?(text) !reliable_input?(text) end def reliable_input?(text) sufficient_text_length?(text) || language_specific_character_set?(text) end def sufficient_text_length?(text) text.split(/\s+/).size >= WORDS_THRESHOLD end def language_specific_character_set?(text) words = text.scan(RELIABLE_CHARACTERS_RE) if words.present? words.reduce(0) { |acc, elem| acc + elem.size }.to_f / text.size > 0.3 else false end end def detect_language_code(text) return if unreliable_input?(text) result = @identifier.find_language(text) iso6391(result.language.to_s).to_sym if result.reliable? end def iso6391(bcp47) iso639 = bcp47.split('-').first # CLD3 returns grandfathered language code for Hebrew return 'he' if iso639 == 'iw' ISO_639.find(iso639).alpha2 end def simplify_text(text) new_text = remove_html(text) new_text.gsub!(FetchLinkCardService::URL_PATTERN, '') new_text.gsub!(Account::MENTION_RE, '') new_text.gsub!(Tag::HASHTAG_RE) { |string| string.gsub(/[#_]/, '#' => '', '_' => ' ').gsub(/[a-z][A-Z]|[a-zA-Z][\d]/) { |s| s.insert(1, ' ') }.downcase } new_text.gsub!(/:#{CustomEmoji::SHORTCODE_RE_FRAGMENT}:/, '') new_text.gsub!(/\s+/, ' ') new_text end def new_scrubber scrubber = Rails::Html::PermitScrubber.new scrubber.tags = %w(br p) scrubber end def scrubber @scrubber ||= new_scrubber end def remove_html(text) text = Loofah.fragment(text).scrub!(scrubber).to_s text.gsub!('<br>', "\n") text.gsub!('</p><p>', "\n\n") text.gsub!(/(^<p>|<\/p>$)/, '') text end def default_locale(account) account.user_locale&.to_sym || I18n.default_locale if account.local? end end