1 files changed, 100 insertions, 0 deletions
diff --git a/app/models/glitch/keyword_mute.rb b/app/models/glitch/keyword_mute.rb
new file mode 100644
index 000000000..a2481308f
--- /dev/null
+++ b/app/models/glitch/keyword_mute.rb
@@ -0,0 +1,100 @@
+# frozen_string_literal: true
+# == Schema Information
+#
+# Table name: glitch_keyword_mutes
+#
+#  id         :integer          not null, primary key
+#  account_id :integer          not null
+#  keyword    :string           not null
+#  whole_word :boolean          default(TRUE), not null
+#  created_at :datetime         not null
+#  updated_at :datetime         not null
+#
+
+class Glitch::KeywordMute < ApplicationRecord
+  belongs_to :account, required: true
+
+  validates_presence_of :keyword
+
+  after_commit :invalidate_cached_matchers
+
+  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_matchers
+    Rails.cache.delete(TextMatcher.cache_key(account_id))
+    Rails.cache.delete(TagMatcher.cache_key(account_id))
+  end
+
+  class RegexpMatcher
+    attr_reader :account_id
+    attr_reader :regex
+
+    def initialize(account_id)
+      @account_id = account_id
+      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:text:%s', account_id)
+    end
+
+    def matches?(str)
+      !!(regex =~ str)
+    end
+
+    private
+
+    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
+
+  class TagMatcher < RegexpMatcher
+    def self.cache_key(account_id)
+      format('keyword_mutes:regex:tag:%s', account_id)
+    end
+
+    def matches?(tags)
+      tags.pluck(:name).any? { |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