sources: rename Sources::Strategies to Source::Extractor.

Rename Sources::Strategies to Source::Extractor. A Source::Extractor
represents a thing that extracts information from a given URL.

app/logical/source/extractor/hentai_foundry.rb

@@ -0,0 +1,74 @@
+# frozen_string_literal: true
+
+# @see Source::URL::HentaiFoundry
+module Source
+  class Extractor
+    class HentaiFoundry < Source::Extractor
+      def match?
+        Source::URL::HentaiFoundry === parsed_url
+      end
+
+      def image_urls
+        image = page&.search("#picBox img")
+
+        return [] unless image
+
+        image.to_a.map { |img| URI.join(page_url, img["src"]).to_s }
+      end
+
+      def page_url
+        return nil if illust_id.blank?
+
+        if artist_name.blank?
+          "https://www.hentai-foundry.com/pic-#{illust_id}"
+        else
+          "https://www.hentai-foundry.com/pictures/user/#{artist_name}/#{illust_id}"
+        end
+      end
+
+      def page
+        return nil if page_url.blank?
+
+        response = http.cache(1.minute).get("#{page_url}?enterAgree=1")
+        return nil unless response.status == 200
+
+        response.parse
+      end
+
+      def tags
+        tags = page&.search(".boxbody [rel='tag']") || []
+
+        tags.map do |tag|
+          [tag.text, URI.join(page_url, tag.attr("href")).to_s]
+        end
+      end
+
+      def artist_name
+        parsed_url.username || parsed_referer&.username
+      end
+
+      def profile_url
+        return nil if artist_name.blank?
+        "https://www.hentai-foundry.com/user/#{artist_name}"
+      end
+
+      def artist_commentary_title
+        page&.search("#picBox .imageTitle")&.text
+      end
+
+      def artist_commentary_desc
+        page&.search("#descriptionBox .picDescript")&.to_html
+      end
+
+      def dtext_artist_commentary_desc
+        DText.from_html(artist_commentary_desc).gsub(/\A[[:space:]]+|[[:space:]]+\z/, "").gsub(/\n+/, "\n")
+      end
+
+      def illust_id
+        parsed_url.work_id || parsed_referer&.work_id
+      end
+
+      memoize :page
+    end
+  end
+end