/artists: add wildcard, regex search to url field (#3900)

Allow searching the URL field by regex or by wildcard.

If the query looks like `/twitter/` do a regex search, otherwise if it
looks like `http://www.twitter.com/*` do a wildcard search, otherwise if
it looks like an url do an artist finder search, lastly if it looks like
`twitter` do a `*twitter*` search.

test/unit/artist_test.rb

@@ -2,7 +2,7 @@ require 'test_helper'
 
 class ArtistTest < ActiveSupport::TestCase
   def assert_artist_found(expected_name, source_url)
-    artists = Artist.url_matches(source_url).to_a
+    artists = Artist.find_artists(source_url).to_a
 
     assert_equal(1, artists.size)
     assert_equal(expected_name, artists.first.name, "Testing URL: #{source_url}")
@@ -11,7 +11,7 @@ class ArtistTest < ActiveSupport::TestCase
   end
 
   def assert_artist_not_found(source_url)
-    artists = Artist.url_matches(source_url).to_a
+    artists = Artist.find_artists(source_url).to_a
     assert_equal(0, artists.size, "Testing URL: #{source_url}")
   rescue Net::OpenTimeout
     skip "Remote connection failed for #{source_url}"
@@ -427,6 +427,15 @@ class ArtistTest < ActiveSupport::TestCase
       assert_not_nil(Artist.search(:any_name_matches => "/cat/").first)
     end
 
+    should "search on url and return matches" do
+      bkub = FactoryBot.create(:artist, name: "bkub", url_string: "http://bkub.com")
+
+      assert_equal([bkub.id], Artist.search(url_matches: "bkub").map(&:id))
+      assert_equal([bkub.id], Artist.search(url_matches: "*bkub*").map(&:id))
+      assert_equal([bkub.id], Artist.search(url_matches: "/rifyu|bkub/").map(&:id))
+      assert_equal([bkub.id], Artist.search(url_matches: "http://bkub.com/test.jpg").map(&:id))
+    end
+
     should "search on has_tag and return matches" do
       post = FactoryBot.create(:post, tag_string: "bkub")
       bkub = FactoryBot.create(:artist, name: "bkub")