module ActionController::ImplicitRender

def default_render(*args)
  if template_exists?(action_name.to_s, _prefixes, variants: request.variant)
    render(*args)
  elsif any_templates?(action_name.to_s, _prefixes)
    message = "#{self.class.name}\##{action_name} is missing a template " \
      "for this request format and variant.\n" \
      "\nrequest.formats: #{request.formats.map(&:to_s).inspect}" \
      "\nrequest.variant: #{request.variant.inspect}"
    raise ActionController::UnknownFormat, message
  elsif interactive_browser_request?
    message = "#{self.class.name}\##{action_name} is missing a template " \
      "for this request format and variant.\n\n" \
      "request.formats: #{request.formats.map(&:to_s).inspect}\n" \
      "request.variant: #{request.variant.inspect}\n\n" \
      "NOTE! For XHR/Ajax or API requests, this action would normally " \
      "respond with 204 No Content: an empty white screen. Since you're " \
      "loading it in a web browser, we assume that you expected to " \
      "actually render a template, not nothing, so we're showing an " \
      "error to be extra-clear. If you expect 204 No Content, carry on. " \
      "That's what you'll get from an XHR or API request. Give it a shot."
    raise ActionController::UnknownFormat, message
  else
    logger.info "No template found for #{self.class.name}\##{action_name}, rendering head :no_content" if logger
    super
  end
end

def interactive_browser_request?
  request.get? && request.format == Mime[:html] && !request.xhr?
end

def method_for_action(action_name)
  super || if template_exists?(action_name.to_s, _prefixes)
    "default_render"
  end
end