discourse/app/services/word_watcher.rb

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# frozen_string_literal: true
class WordWatcher
REPLACEMENT_LETTER ||= CGI.unescape_html("■")
def initialize(raw)
@raw = raw
end
@cache_enabled = true
def self.disable_cache
@cache_enabled = false
end
def self.cache_enabled?
@cache_enabled
end
def self.words_for_action(action)
words = WatchedWord
.where(action: WatchedWord.actions[action.to_sym])
.limit(WatchedWord::MAX_WORDS_PER_ACTION)
.order(:id)
if WatchedWord.has_replacement?(action.to_sym)
words.pluck(:word, :replacement).to_h
else
words.pluck(:word)
end
end
def self.words_for_action_exists?(action)
WatchedWord.where(action: WatchedWord.actions[action.to_sym]).exists?
end
def self.get_cached_words(action)
if cache_enabled?
Discourse.cache.fetch(word_matcher_regexp_key(action), expires_in: 1.day) do
words_for_action(action).presence
end
else
words_for_action(action).presence
end
end
# This regexp is run in miniracer, and the client JS app
# Make sure it is compatible with major browsers when changing
# hint: non-chrome browsers do not support 'lookbehind'
def self.word_matcher_regexp(action, raise_errors: false)
words = get_cached_words(action)
if words
if WatchedWord.has_replacement?(action.to_sym)
words = words.keys
end
words = words.map do |w|
word = word_to_regexp(w)
word = "(#{word})" if SiteSetting.watched_words_regular_expressions?
word
end
regexp = words.join('|')
if !SiteSetting.watched_words_regular_expressions?
regexp = "(#{regexp})"
regexp = "(?:\\W|^)#{regexp}(?=\\W|$)"
end
Regexp.new(regexp, Regexp::IGNORECASE)
end
rescue RegexpError
raise if raise_errors
nil # Admin will be alerted via admin_dashboard_data.rb
end
def self.word_matcher_regexps(action)
if words = get_cached_words(action)
words.map { |w, r| [word_to_regexp(w, whole: true), r] }.to_h
end
end
def self.word_to_regexp(word, whole: false)
if SiteSetting.watched_words_regular_expressions?
# Strip ruby regexp format if present, we're going to make the whole thing
# case insensitive anyway
regexp = word.start_with?("(?-mix:") ? word[7..-2] : word
regexp = "(#{regexp})" if whole
return regexp
end
regexp = Regexp.escape(word).gsub("\\*", '\S*')
if whole && !SiteSetting.watched_words_regular_expressions?
regexp = "(?:\\W|^)(#{regexp})(?=\\W|$)"
end
regexp
end
def self.word_matcher_regexp_key(action)
"watched-words-list:#{action}"
end
def self.censor(html)
regexp = word_matcher_regexp(:censor)
return html if regexp.blank?
doc = Nokogiri::HTML5::fragment(html)
doc.traverse do |node|
node.content = censor_text_with_regexp(node.content, regexp) if node.text?
end
doc.to_s
end
def self.censor_text(text)
regexp = word_matcher_regexp(:censor)
return text if regexp.blank?
censor_text_with_regexp(text, regexp)
end
def self.apply_to_text(text)
if regexp = word_matcher_regexp(:censor)
text = censor_text_with_regexp(text, regexp)
end
%i[replace link]
.flat_map { |type| word_matcher_regexps(type).to_a }
.reduce(text) do |t, (word_regexp, replacement)|
t.gsub(Regexp.new(word_regexp)) { |match| "#{match[0]}#{replacement}" }
end
end
def self.clear_cache!
WatchedWord.actions.each do |a, i|
Discourse.cache.delete word_matcher_regexp_key(a)
end
end
def requires_approval?
word_matches_for_action?(:require_approval)
end
def should_flag?
word_matches_for_action?(:flag)
end
def should_block?
word_matches_for_action?(:block, all_matches: true)
end
def should_silence?
word_matches_for_action?(:silence)
end
def word_matches_for_action?(action, all_matches: false)
regexp = self.class.word_matcher_regexp(action)
if regexp
match = regexp.match(@raw)
return match if !all_matches || !match
if SiteSetting.watched_words_regular_expressions?
set = Set.new
@raw.scan(regexp).each do |m|
if Array === m
set.add(m.find(&:present?))
elsif String === m
set.add(m)
end
end
matches = set.to_a
else
matches = @raw.scan(regexp)
matches.flatten!
matches.uniq!
end
matches.compact!
matches.sort!
matches
else
false
end
end
def word_matches?(word)
Regexp.new(WordWatcher.word_to_regexp(word, whole: true), Regexp::IGNORECASE).match?(@raw)
end
private
def self.censor_text_with_regexp(text, regexp)
text.gsub(regexp) do |match|
# the regex captures leading whitespaces
padding = match.size - match.lstrip.size
if padding > 0
match[0..padding - 1] + REPLACEMENT_LETTER * (match.size - padding)
else
REPLACEMENT_LETTER * match.size
end
end
end
end