/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.

app/logical/sources/strategies/base.rb

@@ -153,7 +153,7 @@ module Sources
       end
 
       def artists
-        Artist.url_matches(normalize_for_artist_finder)
+        Artist.find_artists(normalize_for_artist_finder)
       end
 
       def file_url

app/models/artist.rb

@@ -147,7 +147,7 @@ class Artist < ApplicationRecord
         %r!\Ahttps?://(?:[a-zA-Z0-9_-]+\.)*#{domain}/\z!i
       end)
 
-      def url_matches(url)
+      def find_artists(url)
         url = ArtistUrl.normalize(url)
         artists = []
 
@@ -469,6 +469,18 @@ class Artist < ApplicationRecord
       end
     end
 
+    def url_matches(query)
+      if query =~ %r!\A/(.*)/\z!
+        where(id: ArtistUrl.where_regex(:url, $1).select(:artist_id))
+      elsif query.include?("*")
+        where(id: ArtistUrl.where_like(:url, query).select(:artist_id))
+      elsif query =~ %r!\Ahttps?://!i
+        find_artists(query)
+      else
+        where(id: ArtistUrl.where_like(:url, "*#{query}*").select(:artist_id))
+      end
+    end
+
     def search(params)
       q = super