#!/usr/bin/env python3
"""
HomeOS discovery sidecar. Scans the LAN for participants (mDNS via zeroconf, SSDP via
UPnP) and publishes findings to MQTT under homeos/discovery/<source>/<id> as the
'sidecar' user. Runs with network_mode: host so multicast reaches the smart-home VLAN.
PHP can't do multicast listening from the bridge network — hence this sidecar.
"""
import json
import os
import re
import signal
import socket
import time

import paho.mqtt.client as mqtt
from zeroconf import ServiceBrowser, ServiceListener, Zeroconf

MQTT_HOST = os.environ.get("MQTT_HOST", "127.0.0.1")
MQTT_PORT = int(os.environ.get("MQTT_PORT", "1883"))
MQTT_USERNAME = os.environ.get("MQTT_USERNAME", "sidecar")
MQTT_PASSWORD = os.environ.get("MQTT_PASSWORD", "")

# Service types worth surfacing (Shelly announces _shelly._tcp; plus generic HTTP/IoT).
SERVICE_TYPES = [
    "_shelly._tcp.local.",
    "_http._tcp.local.",
    "_hap._tcp.local.",          # HomeKit accessories
    "_googlecast._tcp.local.",   # Chromecast / Google TV
    "_printer._tcp.local.",
]

_slug = re.compile(r"[^a-z0-9_-]+")


def publish(client, source, identifier, payload):
    ident = _slug.sub("-", identifier.lower()).strip("-") or "unknown"
    topic = f"homeos/discovery/{source}/{ident}"
    client.publish(topic, json.dumps(payload), qos=1, retain=True)
    print(f"[discovery] {source} {ident}: {payload.get('name')}", flush=True)


class MdnsListener(ServiceListener):
    def __init__(self, client):
        self.client = client

    def _emit(self, zc, type_, name):
        try:
            info = zc.get_service_info(type_, name, timeout=3000)
        except Exception:
            info = None
        if not info:
            return
        addresses = []
        try:
            addresses = [socket.inet_ntoa(a) for a in info.addresses if len(a) == 4]
        except Exception:
            pass
        props = {}
        for k, v in (info.properties or {}).items():
            try:
                props[k.decode()] = v.decode() if isinstance(v, bytes) else v
            except Exception:
                pass
        payload = {
            "source": "mdns",
            "name": name.split(".")[0],
            "service": type_,
            "ip": addresses[0] if addresses else None,
            "port": info.port,
            "properties": props,
        }
        publish(self.client, "mdns", name, payload)

    def add_service(self, zc, type_, name):
        self._emit(zc, type_, name)

    def update_service(self, zc, type_, name):
        self._emit(zc, type_, name)

    def remove_service(self, zc, type_, name):
        pass


def main():
    client = mqtt.Client(client_id="homeos-discovery")
    if MQTT_USERNAME:
        client.username_pw_set(MQTT_USERNAME, MQTT_PASSWORD)
    client.connect(MQTT_HOST, MQTT_PORT, keepalive=30)
    client.loop_start()
    print(f"[discovery] connected to mqtt {MQTT_HOST}:{MQTT_PORT}, scanning…", flush=True)

    zc = Zeroconf()
    listener = MdnsListener(client)
    browsers = [ServiceBrowser(zc, t, listener) for t in SERVICE_TYPES]

    running = {"v": True}
    signal.signal(signal.SIGTERM, lambda *_: running.update(v=False))
    signal.signal(signal.SIGINT, lambda *_: running.update(v=False))

    while running["v"]:
        time.sleep(1)

    zc.close()
    client.loop_stop()
    client.disconnect()
    print("[discovery] stopped", flush=True)


if __name__ == "__main__":
    main()