1 files changed, 38 insertions, 0 deletions
diff --git a/activestorage/app/models/active_storage/identification.rb b/activestorage/app/models/active_storage/identification.rb
new file mode 100644
index 0000000000..4f295257ae
--- /dev/null
+++ b/activestorage/app/models/active_storage/identification.rb
@@ -0,0 +1,38 @@
+# frozen_string_literal: true
+
+class ActiveStorage::Identification
+  attr_reader :blob
+
+  def initialize(blob)
+    @blob = blob
+  end
+
+  def apply
+    blob.update!(content_type: content_type, identified: true) unless blob.identified?
+  end
+
+  private
+    def content_type
+      Marcel::MimeType.for(identifiable_chunk, name: filename, declared_type: declared_content_type)
+    end
+
+
+    def identifiable_chunk
+      Net::HTTP.start(uri.host, uri.port, use_ssl: uri.scheme == "https") do |client|
+        client.get(uri, "Range" => "0-4096").body
+      end
+    end
+
+    def uri
+      @uri ||= URI.parse(blob.service_url)
+    end
+
+
+    def filename
+      blob.filename.to_s
+    end
+
+    def declared_content_type
+      blob.content_type
+    end
+end