# File lib/pdfkit/middleware.rb, line 15
    def _call(env)
      @request    = Rack::Request.new(env)
      @render_pdf = false

      set_request_to_render_as_pdf(env) if render_as_pdf?
      status, headers, response = @app.call(env)

      if rendering_pdf? && headers['Content-Type'] =~ /text\/html|application\/xhtml\+xml/
        body = response.respond_to?(:body) ? response.body : response.join
        body = body.join if body.is_a?(Array)

        root_url = root_url(env)
        protocol = protocol(env)
        options = @options.merge(root_url: root_url, protocol: protocol)

        if headers['PDFKit-javascript-delay']
          options.merge!(javascript_delay: headers.delete('PDFKit-javascript-delay').to_i)
        end

        body = PDFKit.new(body, options).to_pdf
        response = [body]

        if headers['PDFKit-save-pdf']
          File.open(headers['PDFKit-save-pdf'], 'wb') { |file| file.write(body) } rescue nil
          headers.delete('PDFKit-save-pdf')
        end

        unless @caching
          # Do not cache PDFs
          headers.delete('ETag')
          headers.delete('Cache-Control')
        end

        headers['Content-Length'] = (body.respond_to?(:bytesize) ? body.bytesize : body.size).to_s
        headers['Content-Type']   = 'application/pdf'
      end

      [status, headers, response]
    end