From 6b6586f5d099a9089c8bf9dc7d7406a86c0a48eb Mon Sep 17 00:00:00 2001
From: Matt Jankowski <matt@jankowski.online>
Date: Thu, 25 Jan 2024 08:00:34 -0500
Subject: [PATCH] Add `CustomFilterKeyword#to_regex` method (#28893)

---
 app/models/custom_filter.rb               | 11 +------
 app/models/custom_filter_keyword.rb       | 16 +++++++++++
 spec/models/custom_filter_keyword_spec.rb | 35 +++++++++++++++++++++++
 3 files changed, 52 insertions(+), 10 deletions(-)
 create mode 100644 spec/models/custom_filter_keyword_spec.rb

diff --git a/app/models/custom_filter.rb b/app/models/custom_filter.rb
index 371267fc281..c8120c23954 100644
--- a/app/models/custom_filter.rb
+++ b/app/models/custom_filter.rb
@@ -68,16 +68,7 @@ class CustomFilter < ApplicationRecord
 
       scope = CustomFilterKeyword.includes(:custom_filter).where(custom_filter: { account_id: account_id }).where(Arel.sql('expires_at IS NULL OR expires_at > NOW()'))
       scope.to_a.group_by(&:custom_filter).each do |filter, keywords|
-        keywords.map! do |keyword|
-          if keyword.whole_word
-            sb = /\A[[:word:]]/.match?(keyword.keyword) ? '\b' : ''
-            eb = /[[:word:]]\z/.match?(keyword.keyword) ? '\b' : ''
-
-            /(?mix:#{sb}#{Regexp.escape(keyword.keyword)}#{eb})/
-          else
-            /#{Regexp.escape(keyword.keyword)}/i
-          end
-        end
+        keywords.map!(&:to_regex)
 
         filters_hash[filter.id] = { keywords: Regexp.union(keywords), filter: filter }
       end.to_h
diff --git a/app/models/custom_filter_keyword.rb b/app/models/custom_filter_keyword.rb
index 3158b3b79a0..979d0b822e6 100644
--- a/app/models/custom_filter_keyword.rb
+++ b/app/models/custom_filter_keyword.rb
@@ -23,8 +23,24 @@ class CustomFilterKeyword < ApplicationRecord
   before_destroy :prepare_cache_invalidation!
   after_commit :invalidate_cache!
 
+  def to_regex
+    if whole_word?
+      /(?mix:#{to_regex_sb}#{Regexp.escape(keyword)}#{to_regex_eb})/
+    else
+      /#{Regexp.escape(keyword)}/i
+    end
+  end
+
   private
 
+  def to_regex_sb
+    /\A[[:word:]]/.match?(keyword) ? '\b' : ''
+  end
+
+  def to_regex_eb
+    /[[:word:]]\z/.match?(keyword) ? '\b' : ''
+  end
+
   def prepare_cache_invalidation!
     custom_filter.prepare_cache_invalidation!
   end
diff --git a/spec/models/custom_filter_keyword_spec.rb b/spec/models/custom_filter_keyword_spec.rb
new file mode 100644
index 00000000000..4e3ab060a04
--- /dev/null
+++ b/spec/models/custom_filter_keyword_spec.rb
@@ -0,0 +1,35 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe CustomFilterKeyword do
+  describe '#to_regex' do
+    context 'when whole_word is true' do
+      it 'builds a regex with boundaries and the keyword' do
+        keyword = described_class.new(whole_word: true, keyword: 'test')
+
+        expect(keyword.to_regex).to eq(/(?mix:\b#{Regexp.escape(keyword.keyword)}\b)/)
+      end
+
+      it 'builds a regex with starting boundary and the keyword when end with non-word' do
+        keyword = described_class.new(whole_word: true, keyword: 'test#')
+
+        expect(keyword.to_regex).to eq(/(?mix:\btest\#)/)
+      end
+
+      it 'builds a regex with end boundary and the keyword when start with non-word' do
+        keyword = described_class.new(whole_word: true, keyword: '#test')
+
+        expect(keyword.to_regex).to eq(/(?mix:\#test\b)/)
+      end
+    end
+
+    context 'when whole_word is false' do
+      it 'builds a regex with the keyword' do
+        keyword = described_class.new(whole_word: false, keyword: 'test')
+
+        expect(keyword.to_regex).to eq(/test/i)
+      end
+    end
+  end
+end