Add furaffinity support

app/logical/source/url/furaffinity.rb

@@ -0,0 +1,45 @@
+# frozen_string_literal: true
+
+class Source::URL::Furaffinity < Source::URL
+  attr_reader :work_id, :username, :filename
+
+  def self.match?(url)
+    url.domain == "furaffinity.net"
+  end
+
+  def parse
+    case [host, *path_segments]
+
+    # https://www.furaffinity.net/view/46821705/
+    # https://www.furaffinity.net/view/46802202/ (scrap)
+    in _, "view", /^\d+$/ => work_id
+      @work_id = work_id
+
+    # https://d.furaffinity.net/art/iwbitu/1650222955/1650222955.iwbitu_yubi.jpg
+    in _, "art", username, subdir, filename
+      @username = username
+      @filename = filename
+
+    # https://www.furaffinity.net/gallery/iwbitu
+    # https://www.furaffinity.net/scraps/iwbitu/2/?
+    # https://www.furaffinity.net/gallery/iwbitu/folder/133763/Regular-commissions
+    in _, ("gallery" | "user" | "favorites" | "scraps" | "journals"), username, *pages
+      @username = username
+
+    else
+      nil
+    end
+  end
+
+  def image_url?
+    @filename.present?
+  end
+
+  def page_url
+    "https://www.furaffinity.net/view/#{work_id}" if work_id.present?
+  end
+
+  def profile_url
+    "https://www.furaffinity.net/user/#{username}" if username.present?
+  end
+end