Python http server to browse zipped documentations

main.py

import email.utils
import mimetypes
import os
from contextlib import contextmanager
from http import HTTPStatus
from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer
from io import StringIO
from zipfile import ZipFile

DOC_DIR = '/directory/containing/zip/files'
archive_handles = {}


class Buffer(StringIO):
    @contextmanager
    def tag(self, name):
        self.write(f'<{name}>\n')
        yield
        self.write(f'</{name}>\n')


class RequestHandler(BaseHTTPRequestHandler):
    def do_GET(self):
        path = self.path
        if '?' in path:
            path = path.split('?', 1)[0]
        if '#' in path:
            path = path.split('#', 1)[0]

        if path == '/':
            self._send_index()
            return

        parts = path.split('/', 2)
        if len(parts) == 2 or not parts[1].endswith('.zip'):
            self._send_content(HTTPStatus.NOT_FOUND, 'Not Found', 'text/plain')
            return

        _, archive, entry = parts
        self._send_file(archive, entry)

    def _send_content(self, status, content, type, last_modified=None):
        if isinstance(content, str):
            content = content.encode('utf-8')
        self.send_response(status)
        self.send_header('Content-Type', type)
        self.send_header('Content-Length', len(content))
        if last_modified:
            self.send_header('Last-Modified', email.utils.formatdate(last_modified, usegmt=True))
        self.end_headers()
        self.wfile.write(content)

    def _send_index(self):
        buf = Buffer()
        with buf.tag('html'):
            with buf.tag('head'):
                buf.write('<meta charset="utf-8">')
                buf.write('<title>Index</title>')
            with buf.tag('body'):
                with buf.tag('ul'):
                    for file in os.listdir(DOC_DIR):
                        if file.endswith('.zip'):
                            buf.write(f'<li><a href="{file}/">{file}</a></li>')
        self._send_content(HTTPStatus.OK, buf.getvalue().encode('utf-8'), 'text/html')

    def _send_file(self, archive, entry):
        global archive_handles

        if archive not in archive_handles:
            archive_path = os.path.join(DOC_DIR, archive)
            archive_handles[archive] = (ZipFile(archive_path), int(os.path.getmtime(archive_path)))

        zf, zf_time = archive_handles[archive]

        if 'If-Modified-Since' in self.headers:
            ims = int(email.utils.parsedate_to_datetime(self.headers['If-Modified-Since']).timestamp())
            if zf_time <= ims:
                self.send_response(HTTPStatus.NOT_MODIFIED)
                self.end_headers()
                return

        if entry == '' or entry.endswith('/'):
            entry += 'index.html'
        try:
            with zf.open(entry) as f:
                self._send_content(HTTPStatus.OK, f.read(), mimetypes.guess_type(entry)[0], zf_time)
        except KeyError:
            self._send_content(HTTPStatus.NOT_FOUND, 'Not Found', 'text/plain')


with ThreadingHTTPServer(('127.0.0.1', 8008), RequestHandler) as server:
    server.serve_forever()