uploads: refactor /uploads/:id page for multi-file uploads.

app/models/upload_media_asset.rb

@@ -1,6 +1,8 @@
 # frozen_string_literal: true
 
 class UploadMediaAsset < ApplicationRecord
+  extend Memoist
+
   belongs_to :upload
   belongs_to :media_asset, optional: true
 
@@ -23,4 +25,15 @@ class UploadMediaAsset < ApplicationRecord
     q = search_attributes(params, :id, :created_at, :updated_at, :status, :source_url, :page_url, :error, :upload, :media_asset)
     q.apply_default_order(params)
   end
+
+  def finished?
+    active? || failed?
+  end
+
+  def source_strategy
+    return nil if source_url.blank?
+    Sources::Strategies.find(source_url, page_url)
+  end
+
+  memoize :source_strategy
 end