"""预警发布器 (MVP-2 / D18)

将统一 ``AlertEvent`` 格式化为前端/外部系统可消费的 JSON 消息，
并通过 ``MQTTService`` 发布到对应主题。

主题命名规则::

    {prefix}/{event_type}/{source_id}      # 单流单类型
    {prefix}/all                            # 全量订阅
    {prefix}/{event_type}                   # 按事件类型订阅

消息格式 (与前端约定)::

    {
      "alert_id": "...",
      "event_type": "fire",
      "severity": "critical",
      "confidence": 0.92,
      "source_id": "cam-01",
      "rule_name": "fire_critical",
      "first_seen": 1781233417.12,
      "last_seen":  1781233418.45,
      "occurrence_count": 3,
      "detections": [{...}],
      "metadata": {...}
    }
"""

from __future__ import annotations

import logging
import time
from typing import Any, Dict, Iterable, List, Optional

from models.event_schemas import AlertEvent
from .mqtt_service import MQTTService

logger = logging.getLogger(__name__)


# ---------------------------------------------------------------------------
# AlertPublisher
# ---------------------------------------------------------------------------


class AlertPublisher:
    """预警事件发布器。

    Args:
        mqtt_service: MQTT 服务实例
        topic_prefix: 主题前缀
        broadcast_all: 是否同时发布到 ``{prefix}/all`` 总订阅主题
        qos: 发布 QoS 等级
        retain: 是否保留最后一条预警 (用于新订阅者立即获取最近状态)
    """

    def __init__(
        self,
        mqtt_service: MQTTService,
        topic_prefix: str = "video/alerts",
        broadcast_all: bool = True,
        qos: int = 1,
        retain: bool = False,
    ) -> None:
        self._mqtt = mqtt_service
        self.topic_prefix = topic_prefix.rstrip("/")
        self.broadcast_all = broadcast_all
        self.qos = qos
        self.retain = retain
        self._published_count = 0
        self._failed_count = 0

    # ------------------------------------------------------------------
    # 发布
    # ------------------------------------------------------------------

    async def publish_alert(self, alert: AlertEvent) -> bool:
        """发布单条预警事件。

        Returns:
            True 表示至少有一条主题发布成功
        """

        payload = self.format_alert(alert)
        topics = self._build_topics(alert)

        any_success = False
        for topic in topics:
            ok = await self._mqtt.publish(
                topic, payload, qos=self.qos, retain=self.retain
            )
            if ok:
                any_success = True
                self._published_count += 1
                logger.debug("AlertPublisher 已发布 topic=%s alert_id=%s", topic, alert.alert_id)
            else:
                self._failed_count += 1
                logger.warning(
                    "AlertPublisher 发布失败 topic=%s alert_id=%s", topic, alert.alert_id
                )
        return any_success

    async def publish_alerts(self, alerts: Iterable[AlertEvent]) -> int:
        """批量发布预警事件，返回成功条数。"""

        success = 0
        for alert in alerts:
            if await self.publish_alert(alert):
                success += 1
        return success

    # ------------------------------------------------------------------
    # 格式化
    # ------------------------------------------------------------------

    @staticmethod
    def format_alert(alert: AlertEvent) -> Dict[str, Any]:
        """将 AlertEvent 格式化为 dict (JSON 友好)。"""

        return {
            "alert_id": alert.alert_id,
            "event_type": alert.event_type.value,
            "severity": alert.severity.value,
            "confidence": round(alert.confidence, 4),
            "source_id": alert.source_id,
            "rule_name": alert.rule_name,
            "first_seen": alert.first_seen,
            "last_seen": alert.last_seen,
            "occurrence_count": alert.occurrence_count,
            "detections": [
                {
                    "detection_id": d.detection_id,
                    "track_id": d.track_id,
                    "class_name": d.class_name,
                    "label": d.label,
                    "confidence": round(d.confidence, 4),
                    "bbox": d.bbox.to_list(),
                    "source": d.source.value,
                    "model_id": d.model_id,
                    "timestamp": d.timestamp,
                }
                for d in alert.detections
            ],
            "metadata": alert.metadata,
            "published_at": time.time(),
        }

    # ------------------------------------------------------------------
    # 主题构建
    # ------------------------------------------------------------------

    def _build_topics(self, alert: AlertEvent) -> List[str]:
        topics: List[str] = []
        event_type = alert.event_type.value
        source_id = alert.source_id or "unknown"

        # 细粒度主题
        topics.append(f"{self.topic_prefix}/{event_type}/{source_id}")
        # 事件类型订阅
        topics.append(f"{self.topic_prefix}/{event_type}")
        # 总广播
        if self.broadcast_all:
            topics.append(f"{self.topic_prefix}/all")

        return topics

    # ------------------------------------------------------------------
    # 状态
    # ------------------------------------------------------------------

    @property
    def stats(self) -> Dict[str, Any]:
        return {
            "topic_prefix": self.topic_prefix,
            "published_count": self._published_count,
            "failed_count": self._failed_count,
            "mqtt_connected": self._mqtt.is_connected,
        }


__all__ = ["AlertPublisher"]