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/fanbox.rb

@@ -0,0 +1,124 @@
+# frozen_string_literal: true
+
+# @see Source::URL::Fanbox
+module Source
+  class Extractor
+    class Fanbox < Source::Extractor
+      def match?
+        Source::URL::Fanbox === parsed_url
+      end
+
+      def image_urls
+        if parsed_url.image_url?
+          [parsed_url.full_image_url]
+        elsif api_response.present?
+          # There's two ways pics are returned via api:
+          # Pics in proper array: https://yanmi0308.fanbox.cc/posts/1141325
+          # Embedded pics (imageMap): https://www.fanbox.cc/@tsukiori/posts/1080657
+          images = api_response.dig("body", "images").to_a + api_response.dig("body", "imageMap").to_a.map { |id| id[1] }
+          # The following is needed because imageMap is sorted alphabetically rather than by image order
+          sort_order = api_response.dig("body", "blocks").to_a.map { |b| b["imageId"] if b["type"] == "image" }.compact.uniq
+          images = images.sort_by { |img| sort_order.index(img["id"]) } if sort_order.present?
+          images.pluck("originalUrl")
+        else
+          []
+        end
+      end
+
+      def page_url
+        if artist_name.present? && illust_id.present?
+          "https://#{artist_name}.fanbox.cc/posts/#{illust_id}"
+        elsif parsed_url.image_url? && artist_name.present?
+          # Cover images
+          "https://#{artist_name}.fanbox.cc"
+        end
+      end
+
+      def profile_url
+        return if artist_name.blank?
+
+        "https://#{artist_name}.fanbox.cc"
+      end
+
+      def artist_name
+        artist_name_from_url || api_response["creatorId"] || artist_api_response["creatorId"]
+      end
+
+      def display_name
+        api_response.dig("user", "name") || artist_api_response.dig("user", "name")
+      end
+
+      def other_names
+        [artist_name, display_name].compact.uniq
+      end
+
+      def tags
+        api_response["tags"].to_a.map { |tag| [tag, "https://fanbox.cc/tags/#{tag}"] }
+      end
+
+      def artist_commentary_title
+        api_response["title"]
+      end
+
+      def artist_commentary_desc
+        body = api_response["body"]
+        return if body.blank?
+
+        if body["text"].present?
+          body["text"]
+        elsif body["blocks"].present?
+          # Reference: https://official.fanbox.cc/posts/182757
+          # Commentary can get pretty complex, but unfortunately it's served in json format so it's a pain to parse it.
+          # I've left out parsing external embeds because each supported site has its own id mapped to the domain
+          commentary = body["blocks"].map do |node|
+            if node["type"] == "image"
+              body["imageMap"][node["imageId"]]["originalUrl"]
+            else
+              node["text"] || "\n"
+            end
+          end
+          commentary.join("\n")
+        end
+      end
+
+      def illust_id
+        parsed_url.work_id || parsed_referer&.work_id
+      end
+
+      def artist_id_from_url
+        parsed_url.user_id || parsed_referer&.user_id
+      end
+
+      def artist_name_from_url
+        parsed_url.username || parsed_referer&.username
+      end
+
+      def api_response
+        return {} if illust_id.blank?
+        resp = client.get("https://api.fanbox.cc/post.info?postId=#{illust_id}")
+        json_response = JSON.parse(resp)["body"]
+
+        # At some point in 2020 fanbox stopped hiding R18 posts from the api
+        # This check exists in case they ever start blocking them again
+        return {} if json_response["restrictedFor"] == 2 && json_response["body"].blank?
+
+        json_response
+      rescue JSON::ParserError
+        {}
+      end
+
+      def artist_api_response
+        # Needed to fetch artist from cover pages
+        return {} if artist_id_from_url.blank?
+        resp = client.get("https://api.fanbox.cc/creator.get?userId=#{artist_id_from_url}")
+        JSON.parse(resp)["body"]
+      rescue JSON::ParserError
+        {}
+      end
+
+      def client
+        @client ||= http.headers(Origin: "https://fanbox.cc").cache(1.minute)
+      end
+    end
+  end
+end