Handle inline Interactive Forms

lib/rubrik/document.rb

@@ -118,11 +118,22 @@ def fetch_or_create_interactive_form!
       root_ref = objects.trailer[:Root]
       root = T.let(objects.fetch(root_ref), T::Hash[Symbol, T.untyped])
 
-      if root.key?(:AcroForm)
+      interactive_form_value = root[:AcroForm]
+      case interactive_form_value
+      when PDF::Reader::Reference
         form_id = root[:AcroForm]
 
         modified_objects << {id: form_id, value: objects.fetch(form_id).dup}
-      else
+      when Hash
+        interactive_form_id = assign_new_object_id!
+
+        modified_objects << {id: interactive_form_id, value: interactive_form_value.dup}
+
+        new_root = root.dup
+        new_root[:AcroForm] = interactive_form_id
+
+        modified_objects << {id: root_ref, value: new_root}
+      when NilClass
         interactive_form_id = assign_new_object_id!
         modified_objects << {id: interactive_form_id, value: {Fields: []}}
 
@@ -131,6 +142,10 @@ def fetch_or_create_interactive_form!
         updated_root[:AcroForm] = interactive_form_id
 
         modified_objects << {id: root_ref, value: updated_root}
+      else
+        raise Error.new(
+          "Expected dictionary, reference or nil but got " \
+          "#{interactive_form_value.class} on AcroForm entry.")
       end
 
       interactive_form[:SigFlags] = 3 # dont modify, append only

test/rubrik/document_test.rb

@@ -48,6 +48,41 @@ def test_initialize_document_with_interactive_form
       input&.close
     end
 
+    def test_initialize_document_with_unexpected_interactive_form_input
+      # Arrange
+      input = File.open(SupportPDF["unexpected_value_interactive_form"], "rb")
+
+      # Act + Assert
+      assert_raises("Expected dictionary, reference or nil but got Array on AcroForm entry.") do
+        Document.new(input)
+      end
+    ensure
+      input&.close
+    end
+
+    def test_initialize_document_with_inline_interactive_form
+      # Arrange
+      input = File.open(SupportPDF["inline_interactive_form"], "rb")
+
+      # Act
+      document = Document.new(input)
+
+      # Assert
+      assert_equal(input, document.send(:io))
+      assert_equal(5, document.last_object_id)
+      assert_kind_of(PDF::Reader::ObjectHash, document.objects)
+
+      root_ref = PDF::Reader::Reference.new(1, 0)
+      assert_pattern do
+        document.modified_objects => [
+          {id: PDF::Reader::Reference, value: {Fields: [], SigFlags: 3, NeedAppearances: true}},
+          {id: ^root_ref, value: Hash}
+        ]
+      end
+    ensure
+      input&.close
+    end
+
     def test_add_signature_field
       # Arrange
       input = File.open(SupportPDF["with_interactive_form"], "rb")

test/rubrik/sign_test.rb

@@ -115,5 +115,41 @@ def test_document_with_indirect_annots
       output_pdf&.close
       File.delete(output_pdf.path) if output_pdf
     end
+
+    def test_document_with_inline_interactive_form
+      # Arrange
+      input_pdf = File.open(SupportPDF["inline_interactive_form"], "rb")
+      output_pdf = StringIO.new
+      certificate_file = File.open("test/support/demo_cert.pem", "rb")
+
+      private_key = OpenSSL::PKey::RSA.new(certificate_file, "")
+      certificate_file.rewind
+      certificate = OpenSSL::X509::Certificate.new(certificate_file)
+
+      # Act
+      Sign.call(input_pdf, output_pdf, private_key:, certificate:)
+
+      # Assert
+      expected_output = File.open(SupportPDF["inline_interactive_form.expected"], "rb")
+
+      expected_output.readlines.zip(output_pdf.readlines).each do |(expected_line, actual_line)|
+        # We must erase the signature because it is timestampped
+        if actual_line&.match?("/Type /Sig")
+          actual_line.sub!(/<[a-f0-9]+>/, "")
+          expected_line.sub!(/<[a-f0-9]+>/, "")
+        # The signature field name is also random
+        elsif actual_line&.match?(/Signature-[a-f0-9]{4}/)
+          actual_line.sub!(/Signature-[a-f0-9]{4}/, "")
+          expected_line.sub!(/Signature-[a-f0-9]{4}/, "")
+        end
+
+        assert_equal(expected_line, actual_line)
+        end
+    ensure
+      certificate_file&.close
+      output_pdf&.close
+      input_pdf&.close
+      expected_output&.close
+    end
   end
 end