1 files changed, 123 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..49769cb73
--- /dev/null
+++ b/app/models/glitch/keyword_mute.rb
@@ -0,0 +1,123 @@
+# frozen_string_literal: true
+# == Schema Information
+#
+# Table name: glitch_keyword_mutes
+#
+#  id                :bigint(8)        not null, primary key
+#  account_id        :bigint(8)        not null
+#  keyword           :string           not null
+#  whole_word        :boolean          default(TRUE), not null
+#  created_at        :datetime         not null
+#  updated_at        :datetime         not null
+#  apply_to_mentions :boolean          default(TRUE), not null
+#
+
+class Glitch::KeywordMute < ApplicationRecord
+  belongs_to :account, required: true
+
+  validates_presence_of :keyword
+
+  after_commit :invalidate_cached_matchers
+
+  module Scopes
+    Unscoped = 0b00
+    HomeFeed = 0b01
+    Mentions = 0b10
+  end
+
+  def self.text_matcher_for(account_id)
+    TextMatcher.new(account_id)
+  end
+
+  def self.tag_matcher_for(account_id)
+    TagMatcher.new(account_id)
+  end
+
+  def scope
+    s = Scopes::Unscoped
+    s |= Scopes::HomeFeed
+    s |= Scopes::Mentions if apply_to_mentions?
+    s
+  end
+
+  private
+
+  def invalidate_cached_matchers
+    Rails.cache.delete(TextMatcher.cache_key(account_id))
+    Rails.cache.delete(TagMatcher.cache_key(account_id))
+  end
+
+  class CachedKeywordMute
+    attr_reader :keyword
+    attr_reader :whole_word
+    attr_reader :scope
+
+    def initialize(keyword, whole_word, scope)
+      @keyword = keyword
+      @whole_word = whole_word
+      @scope = scope
+    end
+
+    def boundary_regex_for_keyword
+      sb = keyword =~ /\A[[:word:]]/ ? '\b' : ''
+      eb = keyword =~ /[[:word:]]\Z/ ? '\b' : ''
+
+      /(?mix:#{sb}#{Regexp.escape(keyword)}#{eb})/
+    end
+
+    def matches?(str, required_scope)
+      ((required_scope & scope) == required_scope) && \
+        str =~ (whole_word ? boundary_regex_for_keyword : /#{Regexp.escape(keyword)}/i)
+    end
+  end
+
+  class Matcher
+    attr_reader :account_id
+    attr_reader :keywords
+
+    def initialize(account_id)
+      @account_id = account_id
+      @keywords = Rails.cache.fetch(self.class.cache_key(account_id)) { fetch_keywords }
+    end
+
+    protected
+
+    def fetch_keywords
+      Glitch::KeywordMute.select(:whole_word, :keyword, :apply_to_mentions)
+        .where(account_id: account_id)
+        .map { |kw| CachedKeywordMute.new(transform_keyword(kw.keyword), kw.whole_word, kw.scope) }
+    end
+
+    def transform_keyword(keyword)
+      keyword
+    end
+  end
+
+  class TextMatcher < Matcher
+    def self.cache_key(account_id)
+      format('keyword_mutes:regex:text:%s', account_id)
+    end
+
+    def matches?(str, scope)
+      keywords.any? { |kw| kw.matches?(str, scope) }
+    end
+  end
+
+  class TagMatcher < Matcher
+    def self.cache_key(account_id)
+      format('keyword_mutes:regex:tag:%s', account_id)
+    end
+
+    def matches?(tags, scope)
+      tags.pluck(:name).any? do |n|
+        keywords.any? { |kw| kw.matches?(n, scope) }
+      end
+    end
+
+    protected
+
+    def transform_keyword(kw)
+      Tag::HASHTAG_RE =~ kw ? $1 : kw
+    end
+  end
+end