"""Serve dist/ with isolation headers; isolated_server() owns a free-port background server."""
from contextlib import contextmanager
from http.server import SimpleHTTPRequestHandler, ThreadingHTTPServer
from pathlib import Path
from threading import Thread

DIST = Path(__file__).resolve().parent.parent / 'dist'


class Handler(SimpleHTTPRequestHandler):
    def __init__(self, *args, **kwargs):
        super().__init__(*args, directory=str(DIST), **kwargs)

    def end_headers(self):
        self.send_header('Cache-Control', 'no-store')
        self.send_header('Cross-Origin-Opener-Policy', 'same-origin')
        self.send_header('Cross-Origin-Embedder-Policy', 'require-corp')
        super().end_headers()

    def log_message(self, format, *args):
        pass


@contextmanager
def isolated_server():
    with ThreadingHTTPServer(('127.0.0.1', 0), Handler) as server:
        thread = Thread(target=server.serve_forever, daemon=True)
        thread.start()
        try:
            yield f'http://127.0.0.1:{server.server_port}'
        finally:
            server.shutdown()
            thread.join()