"""EventBus shim — drop-in for Sanad's core/event_bus.py API across containers.

Same surface as the in-process bus (`on` / `off` / `emit` / `emit_sync`) so
existing Sanad call-sites change only their *import*, not their logic. When
`pyzmq` is importable AND `SANAD_BUS_ADDR` is set, events are also published to
/ received from the central `sanad-busd` XPUB/XSUB proxy, so handlers in OTHER
containers fire too. Otherwise it degrades to a pure in-process bus (identical
behavior to today's monolith) — which is all P1-standalone needs.

Wire format on ZMQ: multipart [topic_bytes, json(kwargs)+_origin]. Each process
tags messages with a random origin id and ignores its own echoes.

Env:
    SANAD_BUS_PUB   address this process PUBLISHES to   (default tcp://127.0.0.1:5560)
    SANAD_BUS_SUB   address this process SUBSCRIBES from (default tcp://127.0.0.1:5561)
    SANAD_BUS_ADDR  if set (any value), enable ZMQ mode using the two above

Kept Python-3.8 compatible.
"""
from __future__ import annotations

import asyncio
import json
import os
import threading
import uuid
from collections import defaultdict
from typing import Any, Callable, Dict, List

try:
    import zmq  # type: ignore
    _HAVE_ZMQ = True
except Exception:
    _HAVE_ZMQ = False

try:
    # reuse Sanad's logger when running inside the image; fall back to print
    from Project.Sanad.core.logger import get_logger  # type: ignore
    _log = get_logger("sanad_bus", to_console=False)
except Exception:  # pragma: no cover
    class _P(object):
        def __getattr__(self, _n):
            return lambda *a, **k: None
    _log = _P()


class Bus(object):
    def __init__(self) -> None:
        self._lock = threading.Lock()
        self._listeners = defaultdict(list)  # type: Dict[str, List[Callable]]
        self._origin = uuid.uuid4().hex
        self._zmq_enabled = False
        self._pub = None
        self._ctx = None
        self._sub_thread = None
        self._stop = threading.Event()

    # ── pub/sub registration (same as core/event_bus.EventBus) ──
    def on(self, event: str, callback: Callable) -> None:
        with self._lock:
            self._listeners[event].append(callback)

    def off(self, event: str, callback: Callable) -> None:
        with self._lock:
            try:
                self._listeners[event].remove(callback)
            except ValueError:
                pass

    async def emit(self, event: str, **kwargs: Any) -> None:
        self._publish(event, kwargs)
        await self._dispatch_async(event, kwargs)

    def emit_sync(self, event: str, **kwargs: Any) -> None:
        self._publish(event, kwargs)
        self._dispatch_sync(event, kwargs)

    # ── local dispatch (mirrors core/event_bus semantics) ──
    def _dispatch_sync(self, event: str, kwargs: Dict[str, Any]) -> None:
        with self._lock:
            handlers = list(self._listeners.get(event, []))
        for h in handlers:
            try:
                if asyncio.iscoroutinefunction(h):
                    try:
                        loop = asyncio.get_running_loop()
                        loop.create_task(h(**kwargs))
                    except RuntimeError:
                        _log.warning("async handler for %s dropped (no loop)", event)
                    continue
                res = h(**kwargs)
                if asyncio.iscoroutine(res):
                    try:
                        asyncio.get_running_loop().create_task(res)
                    except RuntimeError:
                        res.close()
            except Exception:
                _log.exception("handler for %s failed", event)

    async def _dispatch_async(self, event: str, kwargs: Dict[str, Any]) -> None:
        with self._lock:
            handlers = list(self._listeners.get(event, []))
        for h in handlers:
            try:
                res = h(**kwargs)
                if asyncio.iscoroutine(res):
                    await res
            except Exception:
                _log.exception("handler for %s failed", event)

    # ── ZMQ transport (optional) ──
    def connect(self) -> bool:
        """Enable cross-container mode. Safe to call once at startup; no-op if
        pyzmq missing or SANAD_BUS_ADDR unset. Returns True if ZMQ is active."""
        if self._zmq_enabled:
            return True
        if not _HAVE_ZMQ or not os.environ.get("SANAD_BUS_ADDR"):
            _log.info("bus: in-process mode (zmq=%s, addr=%s)",
                      _HAVE_ZMQ, bool(os.environ.get("SANAD_BUS_ADDR")))
            return False
        pub_addr = os.environ.get("SANAD_BUS_PUB", "tcp://127.0.0.1:5560")
        sub_addr = os.environ.get("SANAD_BUS_SUB", "tcp://127.0.0.1:5561")
        try:
            self._ctx = zmq.Context.instance()
            self._pub = self._ctx.socket(zmq.PUB)
            self._pub.connect(pub_addr)
            self._sub_thread = threading.Thread(
                target=self._sub_loop, args=(sub_addr,), daemon=True)
            self._sub_thread.start()
            self._zmq_enabled = True
            _log.info("bus: ZMQ mode pub=%s sub=%s origin=%s",
                      pub_addr, sub_addr, self._origin[:8])
            return True
        except Exception:
            _log.exception("bus: ZMQ connect failed — staying in-process")
            return False

    def _publish(self, event: str, kwargs: Dict[str, Any]) -> None:
        if not self._zmq_enabled or self._pub is None:
            return
        try:
            body = dict(kwargs)
            body["_origin"] = self._origin
            self._pub.send_multipart(
                [event.encode("utf-8"), json.dumps(body, default=str).encode("utf-8")])
        except Exception:
            _log.exception("bus: publish %s failed", event)

    def _sub_loop(self, sub_addr: str) -> None:
        sub = self._ctx.socket(zmq.SUB)
        sub.connect(sub_addr)
        sub.setsockopt(zmq.SUBSCRIBE, b"")  # all topics; filter locally by listeners
        while not self._stop.is_set():
            try:
                if sub.poll(timeout=500):
                    topic, raw = sub.recv_multipart()
                    event = topic.decode("utf-8", "replace")
                    data = json.loads(raw.decode("utf-8", "replace"))
                    if data.pop("_origin", None) == self._origin:
                        continue  # skip our own echo
                    self._dispatch_sync(event, data)
            except Exception:
                _log.exception("bus: sub loop error")
        try:
            sub.close(0)
        except Exception:
            pass

    def close(self) -> None:
        self._stop.set()
        for s in (self._pub,):
            try:
                if s is not None:
                    s.close(0)
            except Exception:
                pass


# singleton — `from sanad_pkg.bus import bus`
bus = Bus()