class Aws::S3::Encryption::EncryptHandler

def apply_encryption_cipher(context, cipher)
  io = context.params[:body] || ''
  io = StringIO.new(io) if String === io
  context.params[:body] = IOEncrypter.new(cipher, io)
  context.params[:metadata] ||= {}
  context.params[:metadata]['x-amz-unencrypted-content-length'] = io.size
  if md5 = context.params.delete(:content_md5)
    context.params[:metadata]['x-amz-unencrypted-content-md5'] = md5
  end
  context.http_response.on_headers do
    context.params[:body].close
  end
end

def apply_encryption_envelope(context, envelope, cipher)
  context[:encryption][:cipher] = cipher
  if context[:encryption][:envelope_location] == :metadata
    context.params[:metadata] ||= {}
    context.params[:metadata].update(envelope)
  else # :instruction_file
    suffix = context[:encryption][:instruction_file_suffix]
    context.client.put_object(
      bucket: context.params[:bucket],
      key: context.params[:key] + suffix,
      body: Json.dump(envelope)
    )
  end
end

def call(context)
  envelope, cipher = context[:encryption][:cipher_provider].encryption_cipher
  apply_encryption_envelope(context, envelope, cipher)
  apply_encryption_cipher(context, cipher)
  @handler.call(context)
end