Added helper methods for screenshots

app/models/screenshot.rb

@@ -148,4 +148,19 @@ class Screenshot < ApplicationRecord
     self.version.split(/[\-\+]/).first
   end
 
+  # Returns the path to this screenshot's image on disk
+  def disk_path
+    ActiveStorage::Blob.service.send(:path_for, self.image.key)
+  end
+
+  def checksum
+    # local files stored on disk:
+    # url = "#{Rails.root}/public/#{attachment.path}"
+    Digest::MD5.hexdigest(disk_path)
+
+    # remote files stored on another person's computer:
+    #url = attachment.url
+    #Digest::MD5.base64digest(Net::HTTP.get(URI(url)))
+  end
+
 end