"""Windows service that runs the Intrusion Detection Flask web app.

Serves the web UI on localhost using the configured defaults
(``http://127.0.0.1:54666`` from ``app.utils.constants``; the ``WEB_HOST``
and ``WEB_PORT`` environment variables or a local ``.env`` override them).

Manage with (from the project root, in an activated venv):
    python intrusion-detection-service.py install
    python intrusion-detection-service.py start
    python intrusion-detection-service.py stop
    python intrusion-detection-service.py remove
"""

import os
import sys
import threading

import servicemanager
import win32event
import win32service
import win32serviceutil

# Ensure the project root is importable. When the SCM launches the service
# the working directory may be C:\\Windows\\System32, not the project dir.
sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)))

from app.utils.constants import WEB_HOST, WEB_PORT  # noqa: E402


class IntrusionDetectionService(win32serviceutil.ServiceFramework):
    _svc_name_ = "IntrusionDetectionWebUI"
    _svc_display_name_ = "Intrusion Detection Web UI"
    _svc_description_ = (
        "Serves the Intrusion Detection Flask web app on localhost "
        f"(http://{WEB_HOST}:{WEB_PORT})."
    )

    def __init__(self, args):
        win32serviceutil.ServiceFramework.__init__(self, args)
        self.hWaitStop = win32event.CreateEvent(None, 0, 0, None)
        self._flask_thread = None

    def SvcStop(self):
        # Report STOP_PENDING, then signal the main loop; the SCM marks the
        # service STOPPED once SvcDoRun returns (after Flask shuts down).
        self.ReportServiceStatus(win32service.SERVICE_STOP_PENDING)
        win32event.SetEvent(self.hWaitStop)

    def SvcDoRun(self):
        servicemanager.LogMsg(
            servicemanager.EVENTLOG_INFORMATION_TYPE,
            servicemanager.PYS_SERVICE_STARTED,
            (self._svc_name_, '')
        )
        try:
            self.main()
        finally:
            servicemanager.LogMsg(
                servicemanager.EVENTLOG_INFORMATION_TYPE,
                servicemanager.PYS_SERVICE_STOPPED,
                (self._svc_name_, '')
            )

    def main(self):
        from app.web import serve

        # Flask's app.run() blocks, so run it on a daemon thread and keep the
        # service alive here until SvcStop signals the stop event. serve()
        # passes use_reloader=False, which is required under the service host
        # (the reloader would spawn a child process and break the service).
        self._flask_thread = threading.Thread(
            target=serve,
            kwargs={"host": WEB_HOST, "port": WEB_PORT},
            daemon=True,
            name="flask-web",
        )
        self._flask_thread.start()

        win32event.WaitForSingleObject(self.hWaitStop, win32event.INFINITE)


if __name__ == '__main__':
    # Handles both the service-host launch and command-line control
    # (install / start / stop / remove).
    win32serviceutil.HandleCommandLine(IntrusionDetectionService)