#!/usr/bin/env python3
"""Dev server that refuses to cache anything.

`python3 -m http.server` sends Last-Modified, and browsers cache ES modules on
it hard enough that a reload can serve a stale js/app.js against a fresh
index.html. That failure is silent and points nowhere near its cause: the new
knobs appear in the markup, nothing wires them, no error is raised, and the
symptom reads as "the feature you just added does not work".
"""
import sys
from http.server import SimpleHTTPRequestHandler, ThreadingHTTPServer


class NoCache(SimpleHTTPRequestHandler):
    def end_headers(self):
        self.send_header('Cache-Control', 'no-store, must-revalidate')
        self.send_header('Expires', '0')
        super().end_headers()

    def log_message(self, fmt, *args):
        if '304' not in fmt % args:
            super().log_message(fmt, *args)


if __name__ == '__main__':
    port = int(sys.argv[1]) if len(sys.argv) > 1 else 8777
    print(f'http://127.0.0.1:{port}  (no-store)')
    ThreadingHTTPServer(('127.0.0.1', port), NoCache).serve_forever()