How to serve pre-generated HTML reports

I have a project that calls an external script, which generates a folder with an HTML report.

My project folder structure looks like this:

        index.html (main html file here)
            css/   (css files here)
            js/    (js files here)
            pages/ (static html files here)

We get an HTML report generated by another tool in the format above. I want to serve the HTML report, which is reports/report_id/index.html, which has a bunch of styling from content/js and content/css, as well as additional static pages under content/pages.

I tried

def report(report_id):
    return send_from_directory(os.path.join('..', reports, 'report_id'), 'index.html')

but this only served the single index.html file independently, and did not consider the other file in the folder. All of the links were also broken.

How would I be able to serve the entire folder from the request?