# -*- coding: utf-8 -*-
"""实时通知统一服务：事件 → 解析接收人 → 落库(权威) + MQTT(实时) + SSE(兜底)。

设计要点：
- 幂等：同用户同 event_code 同 ref_id 不重复落库（MQTT/SSE 重推安全）。
- 静默降级：MQTT 断连 / 通知异常不阻塞业务（try/except 包裹）。
- 角色展开：roles=[...] → 查 users 表展开为具体 user_id。
- 广播：不逐用户落库，走 announcements 表 + MQTT broadcast + SSE。
"""
from __future__ import annotations

import json
import logging

from ..infrastructure.repositories import Database
from ..park.config import settings

log = logging.getLogger("notify")

# 通知负载最小字段（客户端按此渲染 toast/角标，详情走 HTTP）
_NOTIFY_KEYS = ("id", "type", "event", "title", "content", "level", "link",
                "ref_type", "ref_id", "ts", "unread_total", "user_id", "broadcast")


def _mqtt_publish(topic: str, payload: dict) -> None:
    """发布到 EMQX；未连接/失败静默丢弃（SSE 与落库兜底）。"""
    try:
        from ..park.mqtt import hub

        hub.publish(topic, payload, qos=1)
    except Exception:  # noqa: BLE001
        log.debug("MQTT notify publish skipped: %s", topic)


def _sse_emit(payload: dict) -> None:
    """广播到 SSE 兼容通道；客户端按 user_id 过滤。"""
    try:
        from ..park.event_bus import bus

        bus.emit(payload)
    except Exception:  # noqa: BLE001
        log.debug("SSE notify emit skipped")


class NotificationService:
    def __init__(self, db: Database):
        self.db = db

    async def notify(
        self,
        *,
        users: list[str] | None = None,
        roles: list[str] | None = None,
        broadcast: bool = False,
        type: str = "system",
        event_code: str = "",
        title: str = "",
        content: str = "",
        level: str = "info",
        link: str = "",
        ref_type: str = "",
        ref_id: str = "",
        category: str = "",
    ) -> None:
        """统一通知入口。users / roles / broadcast 三选一（可组合 users+roles）。"""
        if not category:
            category = type
        targets: list[str] = list(users or [])
        if roles:
            try:
                targets += await self._users_by_roles(roles)
            except Exception:  # noqa: BLE001
                log.debug("resolve roles failed: %s", roles)
        # 去重
        targets = list(dict.fromkeys(t for t in targets if t))

        if broadcast:
            await self._broadcast(type=type, event_code=event_code, title=title,
                                  content=content, level=level, link=link,
                                  category=category)
            return

        for uid in targets:
            try:
                if await self.db.notifications.exists_dup(uid, event_code, ref_id):
                    continue
                rec = await self.db.notifications.create(
                    uid, type, title, content, category=category,
                    event_code=event_code, level=level, link=link,
                    ref_type=ref_type, ref_id=ref_id)
                payload = self._payload(rec, uid, event_code, title, content,
                                        level, link, ref_type, ref_id)
                _mqtt_publish(f"{settings.TOPIC_NOTIFY_USER}/{uid}", payload)
                _sse_emit(payload)
            except Exception:  # noqa: BLE001
                log.debug("notify to %s failed", uid, exc_info=True)

    async def _broadcast(self, **kw) -> None:
        try:
            await self.db.announcements.create(
                kw.get("title", ""), kw.get("content", ""), category=kw.get("category", "system"),
                level=kw.get("level", "info"), link=kw.get("link", ""))
        except Exception:  # noqa: BLE001
            log.debug("announcement persist failed")
        payload = {
            "id": "", "type": kw.get("type", "system"), "event": kw.get("event_code", "sys.announce"),
            "title": kw.get("title", ""), "content": kw.get("content", ""),
            "level": kw.get("level", "info"), "link": kw.get("link", ""),
            "ref_type": "", "ref_id": "", "ts": _now_iso(),
            "unread_total": 0, "user_id": "*", "broadcast": True,
        }
        _mqtt_publish(settings.TOPIC_NOTIFY_BROADCAST, payload)
        _sse_emit(payload)

    async def _users_by_roles(self, roles: list[str]) -> list[str]:
        from sqlalchemy import select

        from ..infrastructure.models import User

        rows = (await self.db.session.scalars(
            select(User.id).where(User.role.in_(roles))
        )).all()
        return [str(r) for r in rows]

    @staticmethod
    def _payload(rec: dict, uid: str, event_code: str, title: str, content: str,
                 level: str, link: str, ref_type: str, ref_id: str) -> dict:
        return {
            "id": rec.get("id", ""), "type": event_code.split(".")[0] if event_code else "system",
            "event": event_code, "title": title, "content": content,
            "level": level, "link": link, "ref_type": ref_type, "ref_id": ref_id,
            "ts": _now_iso(), "user_id": uid, "broadcast": False,
        }


def _now_iso() -> str:
    from ..infrastructure.repositories import utcnow_iso

    return utcnow_iso()


# ── 便捷函数（供各业务路由直接调用，统一三通道）─────────────────────────

async def notify(db: Database, user_id: str, type: str, title: str, content: str, *,
                 event_code: str = "", level: str = "info", link: str = "",
                 ref_type: str = "", ref_id: str = "", category: str = "") -> None:
    """单用户通知（兼容旧 _notify 调用形态）。"""
    await NotificationService(db).notify(
        users=[user_id], type=type, event_code=event_code, title=title, content=content,
        level=level, link=link, ref_type=ref_type, ref_id=ref_id, category=category)


async def notify_roles(db: Database, roles: list[str], type: str, title: str, content: str, *,
                       event_code: str = "", level: str = "info", link: str = "",
                       ref_type: str = "", ref_id: str = "", category: str = "") -> None:
    """角色组通知（运营/园区待办）。"""
    await NotificationService(db).notify(
        roles=roles, type=type, event_code=event_code, title=title, content=content,
        level=level, link=link, ref_type=ref_type, ref_id=ref_id, category=category)