1 files changed, 36 insertions, 0 deletions
diff --git a/activestorage/app/models/active_storage/filename/parameters.rb b/activestorage/app/models/active_storage/filename/parameters.rb
new file mode 100644
index 0000000000..fb9ea10e49
--- /dev/null
+++ b/activestorage/app/models/active_storage/filename/parameters.rb
@@ -0,0 +1,36 @@
+# frozen_string_literal: true
+
+class ActiveStorage::Filename::Parameters #:nodoc:
+  attr_reader :filename
+
+  def initialize(filename)
+    @filename = filename
+  end
+
+  def combined
+    "#{ascii}; #{utf8}"
+  end
+
+  TRADITIONAL_ESCAPED_CHAR = /[^ A-Za-z0-9!#$+.^_`|~-]/
+
+  def ascii
+    'filename="' + percent_escape(I18n.transliterate(filename.sanitized), TRADITIONAL_ESCAPED_CHAR) + '"'
+  end
+
+  RFC_5987_ESCAPED_CHAR = /[^A-Za-z0-9!#$&+.^_`|~-]/
+
+  def utf8
+    "filename*=UTF-8''" + percent_escape(filename.sanitized, RFC_5987_ESCAPED_CHAR)
+  end
+
+  def to_s
+    combined
+  end
+
+  private
+    def percent_escape(string, pattern)
+      string.gsub(pattern) do |char|
+        char.bytes.map { |byte| "%%%02X" % byte }.join
+      end
+    end
+end