Extract metadata from images and videos

1 files changed, 33 insertions, 0 deletions

diff --git a/activestorage/lib/active_storage/analyzer.rb b/activestorage/lib/active_storage/analyzer.rb
new file mode 100644
index 0000000000..837785a12b
--- /dev/null
+++ b/activestorage/lib/active_storage/analyzer.rb
@@ -0,0 +1,33 @@
+# frozen_string_literal: true
+
+require "active_storage/downloading"
+
+module ActiveStorage
+  # This is an abstract base class for analyzers, which extract metadata from blobs. See
+  # ActiveStorage::Analyzer::ImageAnalyzer for an example of a concrete subclass.
+  class Analyzer
+    include Downloading
+
+    attr_reader :blob
+
+    # Implement this method in a concrete subclass. Have it return true when given a blob from which
+    # the analyzer can extract metadata.
+    def self.accept?(blob)
+      false
+    end
+
+    def initialize(blob)
+      @blob = blob
+    end
+
+    # Override this method in a concrete subclass. Have it return a Hash of metadata.
+    def metadata
+      raise NotImplementedError
+    end
+
+    private
+      def logger
+        ActiveStorage.logger
+      end
+  end
+end