home_control/lib/_arrival_detection.py

"""iPhone arrival detection backed by a Zyxel router's active-client list."""

from __future__ import annotations

import logging
from datetime import datetime
from pathlib import Path
from threading import Event, Thread
from typing import Callable

from lib._zyxel import ZyxelError, ZyxelRouter, normalize_mac

LOG = logging.getLogger("home_control.arrival_detection")


class ArrivalDetector:
    """Debounce connection samples and emit absent -> present transitions."""

    def __init__(self, absent_after: int, present_after: int) -> None:
        if absent_after < 1 or present_after < 1:
            raise ValueError("absent_after and present_after must be at least 1")
        self.absent_after = absent_after
        self.present_after = present_after
        self.state: bool | None = None
        self.present_samples = 0
        self.absent_samples = 0

    def transition(self, present: bool) -> str | None:
        """Return ``arrived`` or ``departed`` after a confirmed state change."""
        self.present_samples = self.present_samples + 1 if present else 0
        self.absent_samples = self.absent_samples + 1 if not present else 0
        if self.state is None:
            if self.present_samples >= self.present_after:
                self.state = True
            elif self.absent_samples >= self.absent_after:
                self.state = False
            return None
        if self.state and self.absent_samples >= self.absent_after:
            self.state = False
            return "departed"
        elif not self.state and self.present_samples >= self.present_after:
            self.state = True
            return "arrived"
        return None

    def sample(self, present: bool) -> bool:
        """Backward-compatible arrival-only result."""
        return self.transition(present) == "arrived"


def _build_router(config: dict) -> ZyxelRouter:
    router = config["zyxel"]
    return ZyxelRouter(
        router["host"], router["username"], router["password"],
        timeout=float(router.get("timeout", 10)),
        verify_tls=bool(router.get("verify_tls", True)),
        hosts_oid=str(router.get("hosts_oid", "lanhosts")),
        debug=bool(router.get("debug", False)),
    )


def _record_event(config: dict, event: dict, mac: str = "") -> None:
    """Record a confirmed presence event before handing it to the controller."""
    LOG.info("%s: %s", event["event"].upper(), event["id"])
    event_log = config.get("event_log")
    if event_log:
        timestamp = datetime.now().astimezone().isoformat(timespec="seconds")
        mac_field = f" mac={mac}" if mac else ""
        with Path(event_log).open("a", encoding="utf-8") as stream:
            stream.write(
                f"{timestamp} {event['event'].upper()} id={event['id']}{mac_field}\n"
            )


def _record_arrival(config: dict, device: dict) -> None:
    """Compatibility helper for callers that record an arrival directly."""
    _record_event(
        config,
        {"sender": "_arrival_detection", "event": "arrived", "id": device["id"], "text": ""},
        device["mac"],
    )


def _configured_devices(config: dict) -> list[dict]:
    devices = config.get("devices")
    if not isinstance(devices, list) or not devices:
        raise ValueError("arrival_detection.devices must contain at least one device")
    if len(devices) > 3:
        raise ValueError("arrival_detection.devices supports at most 3 devices")
    normalized = []
    identifiers = set()
    for index, device in enumerate(devices, start=1):
        if not isinstance(device, dict) or not device.get("id") or not device.get("mac"):
            raise ValueError(f"arrival_detection.devices entry {index} requires id and mac")
        item = dict(device)
        item["mac"] = normalize_mac(str(item["mac"]))
        item["id"] = str(item["id"]).strip().lower()
        if not item["id"]:
            raise ValueError(f"arrival_detection.devices entry {index} requires a non-empty id")
        if item["id"] in identifiers:
            raise ValueError(f"duplicate arrival_detection device id: {item['id']}")
        identifiers.add(item["id"])
        normalized.append(item)
    return normalized


class ArrivalMonitor:
    """Background Zyxel monitor that emits generic controller events."""

    def __init__(self, config: dict, on_event: Callable[[dict], None]) -> None:
        self.config = config
        self.on_event = on_event
        self.devices = _configured_devices(config)
        polling = config.get("polling", {})
        self.detectors = {
            device["mac"]: ArrivalDetector(
                int(polling.get("absent_after", 3)),
                int(polling.get("present_after", 2)),
            )
            for device in self.devices
        }
        self.interval = float(polling.get("interval_seconds", 10))
        self.retry = float(polling.get("error_retry_seconds", 30))
        self.router = _build_router(config)
        self._stop = Event()
        self._thread: Thread | None = None
        self._house_occupied: bool | None = None

    def _connection_states(self) -> dict[str, bool]:
        return self.router.connection_states([device["mac"] for device in self.devices])

    def check_once(self) -> list[str]:
        states = self._connection_states()
        return [
            f"{device['id']}={'connected' if states[device['mac']] else 'absent'}"
            for device in self.devices
        ]

    def _process_states(self, states: dict[str, bool]) -> None:
        for device in self.devices:
            present = states[device["mac"]]
            LOG.debug(
                "%s is %s",
                device["id"],
                "connected" if present else "absent",
            )
            transition = self.detectors[device["mac"]].transition(present)
            if transition:
                event = {
                    "sender": "_arrival_detection",
                    "event": transition,
                    "id": device["id"],
                    "text": "",
                }
                _record_event(self.config, event, device["mac"])
                self.on_event(event)

        known_states = [detector.state for detector in self.detectors.values()]
        if all(state is not None for state in known_states):
            occupied = any(known_states)
            if self._house_occupied is True and not occupied:
                event = {
                    "sender": "_arrival_detection",
                    "event": "empty",
                    "id": "house",
                    "text": "",
                }
                _record_event(self.config, event)
                self.on_event(event)
            self._house_occupied = occupied

    def _run(self) -> None:
        try:
            while not self._stop.is_set():
                try:
                    states = self._connection_states()
                    self._process_states(states)
                    self._stop.wait(self.interval)
                except (ZyxelError, OSError, RuntimeError) as error:
                    LOG.error("poll failed: %s", error)
                    self.router.close()
                    self._stop.wait(self.retry)
        finally:
            self.router.close()

    def start(self) -> None:
        if self._thread and self._thread.is_alive():
            raise RuntimeError("arrival monitor is already running")
        self._thread = Thread(target=self._run, name="zyxel-arrival-monitor")
        self._thread.start()
        LOG.info("Zyxel arrival monitor started")

    def stop(self) -> None:
        self._stop.set()

    def join(self, timeout: float | None = None) -> None:
        if self._thread:
            self._thread.join(timeout)

    @property
    def is_alive(self) -> bool:
        return bool(self._thread and self._thread.is_alive())

    def close(self) -> None:
        """Release resources after a one-shot check."""
        self.router.close()


def create(config: dict, on_event: Callable[[dict], None]) -> ArrivalMonitor:
    """Generic controller plugin factory."""
    return ArrivalMonitor(config, on_event)