Match keyword mute filter on hashtags. #208.

It is reasonable to expect someone to enter #foo to mute hashtag #foo.
However, tags are recorded on statuses without the preceding #.
To adjust for this, we build a separate tag matcher and use
Tag::HASHTAG_RE to extract a hashtag from the hashtag syntax.

3 files changed, 66 insertions, 29 deletions

diff --git a/app/lib/feed_manager.rb b/app/lib/feed_manager.rb
index 414632a8a..e12a5c016 100644
--- a/app/lib/feed_manager.rb
+++ b/app/lib/feed_manager.rb
@@ -141,7 +141,7 @@ class FeedManager
     return false if receiver_id == status.account_id
     return true  if status.reply? && (status.in_reply_to_id.nil? || status.in_reply_to_account_id.nil?)
 
-    return true if keyword_filter?(status, Glitch::KeywordMute.matcher_for(receiver_id))
+    return true if keyword_filter?(status, receiver_id)
 
     check_for_mutes = [status.account_id]
     check_for_mutes.concat(status.mentions.pluck(:account_id))
@@ -170,17 +170,20 @@ class FeedManager
     false
   end
 
-  def keyword_filter?(status, matcher)
-    should_filter   = matcher =~ status.text
-    should_filter ||= matcher =~ status.spoiler_text
-    should_filter ||= status.tags.find_each.any? { |t| matcher =~ t.name }
+  def keyword_filter?(status, receiver_id)
+    text_matcher = Glitch::KeywordMute.text_matcher_for(receiver_id)
+    tag_matcher  = Glitch::KeywordMute.tag_matcher_for(receiver_id)
+
+    should_filter   = text_matcher =~ status.text
+    should_filter ||= text_matcher =~ status.spoiler_text
+    should_filter ||= tag_matcher =~ status.tags
 
     if status.reblog?
       reblog = status.reblog
 
-      should_filter ||= matcher =~ reblog.text
-      should_filter ||= matcher =~ reblog.spoiler_text
-      should_filter ||= reblog.tags.find_each.any? { |t| matcher =~ t.name }
+      should_filter ||= text_matcher =~ reblog.text
+      should_filter ||= text_matcher =~ reblog.spoiler_text
+      should_filter ||= tag_matcher =~ status.tags
     end
 
     !!should_filter
@@ -195,7 +198,7 @@ class FeedManager
 
     should_filter   = Block.where(account_id: receiver_id, target_account_id: check_for_blocks).any?                                     # Filter if it's from someone I blocked, in reply to someone I blocked, or mentioning someone I blocked
     should_filter ||= (status.account.silenced? && !Follow.where(account_id: receiver_id, target_account_id: status.account_id).exists?) # of if the account is silenced and I'm not following them
-    should_filter ||= keyword_filter?(status, Glitch::KeywordMute.matcher_for(receiver_id))                                              # or if the mention contains a muted keyword
+    should_filter ||= keyword_filter?(status, receiver_id)                                                                               # or if the mention contains a muted keyword
 
     should_filter
   end
diff --git a/app/models/glitch/keyword_mute.rb b/app/models/glitch/keyword_mute.rb
index 009de1880..733dd0bc8 100644
--- a/app/models/glitch/keyword_mute.rb
+++ b/app/models/glitch/keyword_mute.rb
@@ -16,51 +16,85 @@ class Glitch::KeywordMute < ApplicationRecord
 
   validates_presence_of :keyword
 
-  after_commit :invalidate_cached_matcher
+  after_commit :invalidate_cached_matchers
 
-  def self.matcher_for(account_id)
-    Matcher.new(account_id)
+  def self.text_matcher_for(account_id)
+    TextMatcher.new(account_id)
+  end
+
+  def self.tag_matcher_for(account_id)
+    TagMatcher.new(account_id)
   end
 
   private
 
-  def invalidate_cached_matcher
-    Rails.cache.delete("keyword_mutes:regex:#{account_id}")
+  def invalidate_cached_matchers
+    Rails.cache.delete(TextMatcher.cache_key(account_id))
+    Rails.cache.delete(TagMatcher.cache_key(account_id))
   end
 
-  class Matcher
+  class RegexpMatcher
     attr_reader :account_id
     attr_reader :regex
 
     def initialize(account_id)
       @account_id = account_id
-      regex_text = Rails.cache.fetch("keyword_mutes:regex:#{account_id}") { regex_text_for_account }
+      regex_text = Rails.cache.fetch(self.class.cache_key(account_id)) { make_regex_text }
       @regex = /#{regex_text}/
     end
 
+    protected
+
+    def keywords
+      Glitch::KeywordMute.where(account_id: account_id).pluck(:whole_word, :keyword)
+    end
+
+    def boundary_regex_for_keyword(keyword)
+      sb = keyword =~ /\A[[:word:]]/ ? '\b' : ''
+      eb = keyword =~ /[[:word:]]\Z/ ? '\b' : ''
+
+      /(?mix:#{sb}#{Regexp.escape(keyword)}#{eb})/
+    end
+  end
+
+  class TextMatcher < RegexpMatcher
+    def self.cache_key(account_id)
+      format('keyword_mutes:regex:%s', account_id)
+    end
+
     def =~(str)
       regex =~ str
     end
 
     private
 
-    def keywords
-      Glitch::KeywordMute.where(account_id: account_id).select(:keyword, :id, :whole_word)
-    end
-
-    def regex_text_for_account
-      kws = keywords.find_each.with_object([]) do |kw, a|
-        a << (kw.whole_word ? boundary_regex_for_keyword(kw.keyword) : kw.keyword)
+    def make_regex_text
+      kws = keywords.map! do |whole_word, keyword|
+        whole_word ? boundary_regex_for_keyword(keyword) : keyword
       end
 
       Regexp.union(kws).source
     end
+  end
 
-    def boundary_regex_for_keyword(keyword)
-      sb = keyword =~ /\A[[:word:]]/ ? '\b' : ''
-      eb = keyword =~ /[[:word:]]\Z/ ? '\b' : ''
+  class TagMatcher < RegexpMatcher
+    def self.cache_key(account_id)
+      format('keyword_mutes:tag:%s', account_id)
+    end
 
-      /(?mix:#{sb}#{Regexp.escape(keyword)}#{eb})/
+    def =~(tags)
+      tags.pluck(:name).detect { |n| regex =~ n }
+    end
+
+    private
+
+    def make_regex_text
+      kws = keywords.map! do |whole_word, keyword|
+        term = (Tag::HASHTAG_RE =~ keyword) ? $1 : keyword
+        whole_word ? boundary_regex_for_keyword(term) : term
+      end
+
+      Regexp.union(kws).source
     end
   end
 end
diff --git a/spec/models/glitch/keyword_mute_spec.rb b/spec/models/glitch/keyword_mute_spec.rb
index 9685c6493..e14af0e6a 100644
--- a/spec/models/glitch/keyword_mute_spec.rb
+++ b/spec/models/glitch/keyword_mute_spec.rb
@@ -4,8 +4,8 @@ RSpec.describe Glitch::KeywordMute, type: :model do
   let(:alice) { Fabricate(:account, username: 'alice').tap(&:save!) }
   let(:bob) { Fabricate(:account, username: 'bob').tap(&:save!) }
 
-  describe '.matcher_for' do
-    let(:matcher) { Glitch::KeywordMute.matcher_for(alice) }
+  describe '.text_matcher_for' do
+    let(:matcher) { Glitch::KeywordMute.text_matcher_for(alice.id) }
 
     describe 'with no mutes' do
       before do