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/mastodon.rb

@@ -0,0 +1,97 @@
+# frozen_string_literal: true
+
+# @see Source::URL::Mastodon
+class Source::Extractor
+  class Mastodon < Source::Extractor
+    def match?
+      Source::URL::Mastodon === parsed_url
+    end
+
+    def domain
+      case site_name
+      when "Pawoo" then "pawoo.net"
+      when "Baraag" then "baraag.net"
+      end
+    end
+
+    def image_urls
+      if parsed_url.image_url?
+        [parsed_url.full_image_url]
+      else
+        api_response.image_urls
+      end
+    end
+
+    def page_url
+      artist_name = artist_name_from_url
+      status_id = status_id_from_url
+      return if status_id.blank?
+
+      if artist_name.present?
+        "https://#{domain}/@#{artist_name}/#{status_id}"
+      else
+        "https://#{domain}/web/statuses/#{status_id}"
+      end
+    end
+
+    def profile_url
+      if artist_name_from_url.present?
+        "https://#{domain}/@#{artist_name_from_url}"
+      elsif api_response.present? && api_response.profile_url.present?
+        api_response.profile_url
+      end
+    end
+
+    def account_url
+      return if account_id.blank?
+      "https://#{domain}/web/accounts/#{account_id}"
+    end
+
+    def profile_urls
+      [profile_url, account_url].compact
+    end
+
+    def artist_name
+      api_response.account_name
+    end
+
+    def artist_name_from_url
+      parsed_url.username || parsed_referer&.username
+    end
+
+    def other_names
+      [api_response.display_name]
+    end
+
+    def account_id
+      parsed_url.user_id || parsed_referer&.user_id || api_response.account_id
+    end
+
+    def status_id_from_url
+      parsed_url.work_id || parsed_referer&.work_id
+    end
+
+    def artist_commentary_desc
+      api_response.commentary
+    end
+
+    def tags
+      api_response.tags
+    end
+
+    def dtext_artist_commentary_desc
+      DText.from_html(artist_commentary_desc) do |element|
+        if element.name == "a"
+          # don't include links to the toot itself.
+          media_urls = api_response.json["media_attachments"].map { |attr| attr["text_url"] }
+          element["href"] = nil if element["href"].in?(media_urls)
+        end
+      end.strip
+    end
+
+    def api_response
+      MastodonApiClient.new(domain, status_id_from_url)
+    end
+    memoize :api_response
+  end
+end