"""Run the web UI's FastAPI app on a background thread.

The radar app already owns the hardware and the Qt event loop, so the web server
lives in a daemon thread inside that process (uvicorn brings its own asyncio loop
for the thread). Control requests hop back to the Qt main thread via the bridge's
queued signals — the web thread never touches Qt directly.
"""

from __future__ import annotations

import logging
import threading

import uvicorn

from python_app.webui.app import create_app
from python_app.webui.controller import WebController

logger = logging.getLogger(__name__)


class WebUiServer:
    """Owns a uvicorn server bound to a controller, run on a daemon thread."""

    def __init__(self, controller: WebController, *, host: str = "0.0.0.0", port: int = 8080) -> None:
        """Build the server for ``controller`` (not started until :meth:`start`)."""
        config = uvicorn.Config(create_app(controller), host=host, port=port, log_level="warning")
        self._server = uvicorn.Server(config)
        self._thread = threading.Thread(target=self._serve, name="radar-webui", daemon=True)

    def start(self) -> None:
        """Start serving on the background thread."""
        self._thread.start()

    def is_alive(self) -> bool:
        """Return whether the server thread is still running."""
        return self._thread.is_alive()

    def _serve(self) -> None:
        """Run uvicorn, surfacing a startup/runtime failure instead of dying silently.

        The bind happens on this thread after ``start()`` has already returned, so a
        failure (e.g. the port is taken) would otherwise be invisible.
        """
        try:
            self._server.run()
        except Exception:  # noqa: BLE001 - log, never crash the host process
            logger.exception("Web UI server thread exited with an error")

    def stop(self) -> None:
        """Ask uvicorn to exit and wait briefly for the thread to unwind."""
        self._server.should_exit = True
        self._thread.join(timeout=5.0)