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/nico_seiga.rb

@@ -0,0 +1,111 @@
+# frozen_string_literal: true
+
+# @see Source::URL::NicoSeiga
+module Source
+  class Extractor
+    class NicoSeiga < Source::Extractor
+      def self.enabled?
+        Danbooru.config.nico_seiga_user_session.present?
+      end
+
+      def match?
+        Source::URL::NicoSeiga === parsed_url
+      end
+
+      def image_urls
+        if image_id.present?
+          [image_url_for("https://seiga.nicovideo.jp/image/source/#{image_id}")]
+        elsif illust_id.present?
+          [image_url_for("https://seiga.nicovideo.jp/image/source/#{illust_id}")]
+        elsif manga_id.present? && api_client.image_ids.present?
+          api_client.image_ids.map { |id| image_url_for("https://seiga.nicovideo.jp/image/source/#{id}") }
+        else
+          [image_url_for(url)]
+        end
+      end
+
+      def image_url_for(url)
+        return url if api_client.blank?
+
+        resp = api_client.head(url)
+        if resp.uri.to_s =~ %r{https?://.+/(\w+/\d+/\d+)\z}i
+          "https://lohas.nicoseiga.jp/priv/#{$1}"
+        else
+          url
+        end
+      end
+
+      def page_url
+        parsed_referer&.page_url || parsed_url.page_url
+      end
+
+      def profile_url
+        "https://seiga.nicovideo.jp/user/illust/#{api_client.user_id}" if api_client&.user_id.present?
+      end
+
+      def artist_name
+        return if api_client.blank?
+        api_client.user_name
+      end
+
+      def artist_commentary_title
+        return if api_client.blank?
+        api_client.title
+      end
+
+      def artist_commentary_desc
+        return if api_client.blank?
+        api_client.description
+      end
+
+      def dtext_artist_commentary_desc
+        DText.from_html(artist_commentary_desc) do |element|
+          if element.name == "font" && element["color"] == "white"
+            element.content = "[spoiler]#{element.content}[/spoiler]"
+          end
+        end.gsub(/[^\w]im(\d+)/, ' seiga #\1 ').chomp
+      end
+
+      def tag_name
+        return if api_client&.user_id.blank?
+        "nicoseiga#{api_client.user_id}"
+      end
+
+      def tags
+        return [] if api_client.blank?
+
+        base_url = "https://seiga.nicovideo.jp/"
+        base_url += "manga/" if manga_id.present?
+        base_url += "tag/"
+
+        api_client.tags.map do |name|
+          [name, base_url + CGI.escape(name)]
+        end
+      end
+
+      def image_id
+        parsed_url.image_id || parsed_referer&.image_id
+      end
+
+      def illust_id
+        parsed_url.illust_id || parsed_referer&.illust_id
+      end
+
+      def manga_id
+        parsed_url.manga_id || parsed_referer&.manga_id
+      end
+
+      def api_client
+        if illust_id.present?
+          NicoSeigaApiClient.new(work_id: illust_id, type: "illust", http: http)
+        elsif manga_id.present?
+          NicoSeigaApiClient.new(work_id: manga_id, type: "manga", http: http)
+        elsif image_id.present?
+          # We default to illust to attempt getting the api anyway
+          NicoSeigaApiClient.new(work_id: image_id, type: "illust", http: http)
+        end
+      end
+      memoize :api_client
+    end
+  end
+end