import socket
import threading
import time
import traceback


BACKEND_HOST = "127.0.0.1"
BACKEND_BIND_HOST = "0.0.0.0"
BACKEND_PORT = 8000
_backend_thread = None
_backend_error = None


def is_port_open(host: str = BACKEND_HOST, port: int = BACKEND_PORT) -> bool:
    with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
        s.settimeout(0.5)
        try:
            s.connect((host, port))
            return True
        except Exception:
            return False


def _run_backend_in_thread() -> None:
    global _backend_error
    try:
        import uvicorn
        import backend_main

        app = getattr(backend_main, "app", None)
        if app is None:
            raise RuntimeError("backend_main.app wurde nicht gefunden.")

        config = uvicorn.Config(
            app=app,
            host=BACKEND_BIND_HOST,
            port=BACKEND_PORT,
            log_level="info",
        )
        server = uvicorn.Server(config)
        server.run()
    except Exception:
        _backend_error = traceback.format_exc()


def start_backend(timeout_seconds: float = 20.0) -> bool:
    global _backend_thread

    if is_port_open():
        return True

    if _backend_thread is None or not _backend_thread.is_alive():
        _backend_thread = threading.Thread(
            target=_run_backend_in_thread,
            name="aza-local-backend",
            daemon=True,
        )
        _backend_thread.start()

    deadline = time.time() + timeout_seconds
    while time.time() < deadline:
        if is_port_open():
            return True
        if _backend_error:
            return False
        time.sleep(0.25)

    return False


def get_backend_error() -> str:
    return _backend_error or ""


if __name__ == "__main__":
    ok = start_backend()
    print("backend_started:", ok)
    if not ok and _backend_error:
        print(_backend_error)