Merge pull request #179 from glitch-soc/keyword-mute

Keyword muting

app/models/glitch.rb

@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+module Glitch
+  def self.table_name_prefix
+    'glitch_'
+  end
+end

app/models/glitch/keyword_mute.rb

@@ -0,0 +1,66 @@
+# 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_matcher
+
+  def self.matcher_for(account_id)
+    Matcher.new(account_id)
+  end
+
+  private
+
+  def invalidate_cached_matcher
+    Rails.cache.delete("keyword_mutes:regex:#{account_id}")
+  end
+
+  class Matcher
+    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 = /#{regex_text}/i
+    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)
+      end
+
+      Regexp.union(kws).source
+    end
+
+    def boundary_regex_for_keyword(keyword)
+      sb = keyword =~ /\A[[:word:]]/ ? '\b' : ''
+      eb = keyword =~ /[[:word:]]\Z/ ? '\b' : ''
+
+      /#{sb}#{Regexp.escape(keyword)}#{eb}/
+    end
+  end
+end