"""Serve the tunie viewer locally so the catalogue dropdown can fetch cached maps.

    python3 serve.py            # serves this folder at http://localhost:8000
    python3 serve.py 9000       # custom port

Browsers block fetch() on file:// URLs, so the Triumph-tables catalogue dropdown
only works when the viewer is served over HTTP. Drag-and-drop works either way.
Run download_maps.py first to populate maps_cache/.
"""

from __future__ import annotations

import http.server
import socketserver
import sys
import webbrowser
from pathlib import Path

HERE = Path(__file__).parent


def main() -> int:
    port = int(sys.argv[1]) if len(sys.argv) > 1 else 8000
    if not (HERE / "maps_cache" / "index.json").exists():
        print("note: maps_cache/index.json not found — run download_maps.py first "
              "for the catalogue dropdown (drag-and-drop still works).")

    handler = lambda *a, **k: http.server.SimpleHTTPRequestHandler(*a, directory=str(HERE), **k)
    with socketserver.TCPServer(("127.0.0.1", port), handler) as httpd:
        url = f"http://localhost:{port}/tunie-viewer.html"
        print(f"serving {HERE} at {url}\nCtrl-C to stop.")
        try:
            webbrowser.open(url)
        except Exception:
            pass
        try:
            httpd.serve_forever()
        except KeyboardInterrupt:
            print("\nstopped.")
    return 0


if __name__ == "__main__":
    raise SystemExit(main())