"""Explicit lifecycle for process-owning background services.

Only the process holding ``ServiceLeaderLock`` may bind SIP, manage ZLM,
spawn recording processes, auto-proxy streams, or emit telemetry.
"""
import atexit
import json
import logging
import os
import threading
import time
from pathlib import Path


logger = logging.getLogger("app.services.lifecycle")
from monitor_runtime.paths import DATA_ROOT
PROJECT_ROOT = DATA_ROOT
DEFAULT_LOCK_PATH = PROJECT_ROOT / ".runtime" / "service-leader.lock"


class ServiceLeaderLock:
    def __init__(self, path=None):
        self.path = Path(path or os.environ.get("MONITOR_SERVICE_LOCK", DEFAULT_LOCK_PATH)).resolve()
        self._handle = None

    @property
    def acquired(self):
        return self._handle is not None

    def acquire(self):
        if self.acquired:
            return True
        self.path.parent.mkdir(parents=True, exist_ok=True)
        handle = open(self.path, "a+b")
        try:
            if os.name == "nt":
                import msvcrt
                handle.seek(0, os.SEEK_END)
                if handle.tell() == 0:
                    handle.write(b"\0")
                    handle.flush()
                handle.seek(0)
                msvcrt.locking(handle.fileno(), msvcrt.LK_NBLCK, 1)
            else:
                import fcntl
                fcntl.flock(handle.fileno(), fcntl.LOCK_EX | fcntl.LOCK_NB)
        except (OSError, IOError):
            handle.close()
            return False
        self._handle = handle
        metadata = json.dumps({"pid": os.getpid(), "started_at": int(time.time())}).encode("utf-8")
        handle.seek(0)
        handle.truncate()
        handle.write(metadata)
        handle.flush()
        return True

    def release(self):
        handle = self._handle
        if handle is None:
            return
        try:
            handle.seek(0)
            if os.name == "nt":
                import msvcrt
                msvcrt.locking(handle.fileno(), msvcrt.LK_UNLCK, 1)
            else:
                import fcntl
                fcntl.flock(handle.fileno(), fcntl.LOCK_UN)
        finally:
            handle.close()
            self._handle = None


class BackgroundCoordinator:
    def __init__(self):
        self._stop = threading.Event()
        self._thread = None

    def start(self):
        if self._thread and self._thread.is_alive():
            return
        self._stop.clear()
        self._thread = threading.Thread(target=self._run, name="service-coordinator", daemon=True)
        self._thread.start()

    def stop(self):
        self._stop.set()
        if self._thread and self._thread.is_alive():
            self._thread.join(timeout=5)

    def _run(self):
        from app.utils.GlobalUtils import GlobalUtils, g_config, g_logger

        if getattr(g_config, "autoAddStreamProxy", False):
            delay = max(0, int(getattr(g_config, "autoAddStreamProxySleep", 15)))
            if not self._stop.wait(delay):
                try:
                    ok, msg = GlobalUtils.addAllStreamProxy()
                    g_logger.info("autoAddStreamProxy ok=%s msg=%s", ok, msg)
                except Exception as exc:
                    g_logger.warning("autoAddStreamProxy failed: %s", exc)

        sequence = 0
        interval = max(60, int(os.environ.get("MONITOR_TELEMETRY_INTERVAL", "4800")))
        while not self._stop.wait(interval):
            if not getattr(g_config, "telemetryEnabled", False):
                continue
            sequence += 1
            try:
                from app.services.telemetry import send_heartbeat
                send_heartbeat(sequence)
            except Exception as exc:
                g_logger.warning("telemetry heartbeat failed: %s", exc)


class ServiceManager:
    def __init__(self, lock=None):
        self.lock = lock or ServiceLeaderLock()
        self.coordinator = BackgroundCoordinator()
        self._started = False
        self._guard = threading.RLock()

    @property
    def is_leader(self):
        return self.lock.acquired

    def start(self):
        from monitor_runtime.licensing import require_license
        require_license()
        with self._guard:
            if self._started:
                return True
            if not self.lock.acquire():
                logger.info("background services skipped: another process is leader")
                return False
            try:
                from app.utils.GlobalUtils import g_config, g_gb28181SipServer
                if getattr(g_config, "autoStartMedia", False):
                    from app.utils.MediaServerManager import get_media_server_manager
                    ok, info = get_media_server_manager().start()
                    logger.info("ZLM explicit start: ok=%s %s", ok, info)
                    if not ok:
                        raise RuntimeError("ZLM startup failed: " + str(info))
                g_gb28181SipServer.start()
                if getattr(g_config, "recordingEnabled", False):
                    from app.recording.manager import get_recording_manager
                    get_recording_manager().start()
                self.coordinator.start()
                self._started = True
                logger.info("background services started as leader pid=%s", os.getpid())
                return True
            except Exception:
                logger.exception("background service startup failed")
                self.stop()
                raise

    def reconcile(self):
        if not self.is_leader:
            return False
        from app.utils.GlobalUtils import g_config
        from app.recording.manager import get_recording_manager
        recording = get_recording_manager()
        if getattr(g_config, "recordingEnabled", False):
            recording.start()
        else:
            recording.stop()
        return True

    def stop(self):
        with self._guard:
            if not self.is_leader:
                return
            self.coordinator.stop()
            try:
                from app.analysis.manager import shutdown_analysis
                shutdown_analysis()
            except Exception:
                logger.exception("analysis shutdown failed")
            try:
                from app.recording.manager import get_recording_manager
                get_recording_manager().stop()
            except Exception:
                logger.exception("recording shutdown failed")
            try:
                from app.utils.GlobalUtils import g_gb28181SipServer
                g_gb28181SipServer.stop()
            except Exception:
                logger.exception("SIP shutdown failed")
            try:
                from app.utils.MediaServerManager import get_media_server_manager
                media = get_media_server_manager()
                if media.managed_pid():
                    media.stop()
            except Exception:
                logger.exception("ZLM shutdown failed")
            self._started = False
            self.lock.release()
            logger.info("background services stopped")


_MANAGER = ServiceManager()
atexit.register(_MANAGER.stop)


def get_service_manager():
    return _MANAGER


def is_service_leader():
    return _MANAGER.is_leader