require "turbo_dev_assets/version"

# Cheat and bypass Rails in development mode if the client attempts to download a static asset
# that's already been downloaded.
#
# Also ensures that assets are not cached in development mode. Around Chrome 29, the behavior
# of `must-revalidate` changed and would often not request assets that had changed.
#
#  To use, include in your project and add the following to development.rb:
#
#  require 'middleware/turbo_dev'
#  config.middleware.insert 0, Middleware::TurboDev
#
class TurboDevAssets
  def initialize(app, settings={})
    @app = app
  end

  def call(env)
    is_asset = (env['REQUEST_PATH'] =~ /^#{Rails.application.config.assets.prefix}\//)

    # hack to bypass all middleware if serving assets, a lot faster 4.5 seconds -> 1.5 seconds
    if (etag = env['HTTP_IF_NONE_MATCH']) && is_asset
      name = $'
      etag = etag.gsub "\"", ""
      asset = Rails.application.assets.find_asset(name)
      if asset && asset.digest == etag
        return [304,{},[]]
      end
    end

    status, headers, response = @app.call(env)
    headers['Cache-Control'] = 'no-cache' if is_asset
    [status, headers, response]
  end
end
