"""
OpenCode `/event` 구독 버스 — 프로세스당 하나.

OpenCode 는 서버 전체 이벤트를 SSE 하나로 흘림. 여기서 한 번만 구독하고
세션별 asyncio.Queue 로 나눠줌. 구독자 없으면 태스크도 안 돌림.
큐 item: dict(이벤트) 또는 None(하트비트 — 60초 무활동/재연결).
"""

import asyncio
import json
import logging

from common.opencode_service import opencode_service

log = logging.getLogger(__name__)


def session_id_of(event: dict) -> str | None:
    props = event.get("properties") or {}
    info = props.get("info") or {}
    part = props.get("part") or {}
    if str(event.get("type", "")).startswith("session."):
        return info.get("id") or props.get("sessionID")
    return part.get("sessionID") or props.get("sessionID") or info.get("sessionID")


class EventBus:
    def __init__(self, source=None):
        # source: async iterator factory — 테스트에서 가짜로 바꿈
        self._source = source or opencode_service.iter_event_jsons
        self._subs: dict[str, set[asyncio.Queue]] = {}
        self._task: asyncio.Task | None = None

    def subscribe(self, session_id: str) -> asyncio.Queue:
        q: asyncio.Queue = asyncio.Queue()
        self._subs.setdefault(session_id, set()).add(q)
        self._ensure_running()
        return q

    def unsubscribe(self, session_id: str, q: asyncio.Queue) -> None:
        subs = self._subs.get(session_id)
        if subs:
            subs.discard(q)
            if not subs:
                del self._subs[session_id]

    def _ensure_running(self) -> None:
        if self._task is None or self._task.done():
            self._task = asyncio.get_running_loop().create_task(self._pump(), name="opencode-event-pump")

    async def _pump(self) -> None:
        try:
            async for payload in self._source():
                if payload is None:
                    for subs in list(self._subs.values()):
                        for q in list(subs):
                            q.put_nowait(None)
                    continue
                try:
                    event = json.loads(payload)
                except ValueError:
                    continue
                sid = session_id_of(event)
                if not sid:
                    continue
                for q in list(self._subs.get(sid, ())):
                    q.put_nowait(event)
        except asyncio.CancelledError:
            raise
        except Exception:  # noqa: BLE001
            log.exception("이벤트 펌프 죽음 — 다음 구독 때 재시작")
        finally:
            self._task = None


event_bus = EventBus()