"""健康检查 — 僵尸检测 + 告警

连续 N tick 无变更（events 表无新事件）→ 写 observation 告警。
项目恢复活动后 → 自动解除告警。
"""

from __future__ import annotations

import json
import logging
from pathlib import Path
from typing import Any, Dict

from src.blackboard.db import get_connection
from src.blackboard.queries import Queries

logger = logging.getLogger("moziplus-v2.health")


class HealthChecker:
    """per-project 僵尸检测"""

    def __init__(self, zombie_threshold: int = 20):
        """
        Args:
            zombie_threshold: 连续多少 tick 无变更视为僵尸
        """
        self.zombie_threshold = zombie_threshold
        # project_id → 连续无变更 tick 数
        self._stale_ticks: Dict[str, int] = {}
        # project_id → 是否已告警
        self._alerted: Dict[str, bool] = {}
        # project_id → 上次检查时的 event count
        self._last_event_count: Dict[str, int] = {}

    def check(self, project_id: str, db_path: Path,
              tick_num: int) -> Dict[str, Any]:
        """检查单个项目的健康状态

        Returns:
            {"healthy": bool, "zombie": bool, "stale_ticks": int,
             "alert_written": bool, "resolved": bool}
        """
        str(db_path)
        result: Dict[str, Any] = {
            "healthy": True,
            "zombie": False,
            "stale_ticks": self._stale_ticks.get(project_id, 0),
            "alert_written": False,
            "resolved": False,
        }

        if not db_path.exists():
            return result

        queries = Queries(db_path)

        # 用 event count 变化判断是否有真实变更
        conn = queries._conn()
        try:
            conn.execute(
                "SELECT COUNT(*) FROM events").fetchone()[0]
            non_tick_events = conn.execute(
                "SELECT COUNT(*) FROM events WHERE event_type != 'daemon_tick' "
                "AND event_type != 'agent_zombie_detected'"
            ).fetchone()[0]
        finally:
            conn.close()

        last_count = self._last_event_count.get(project_id, 0)
        self._last_event_count[project_id] = non_tick_events
        has_real_change = non_tick_events > last_count

        if has_real_change:
            # 有真实变更 → 重置计数
            old_stale = self._stale_ticks.pop(project_id, 0)
            was_alerted = self._alerted.pop(project_id, False)
            if was_alerted and old_stale >= self.zombie_threshold:
                # 解除告警
                self._write_resolution(db_path, project_id, tick_num)
                result["resolved"] = True
            result["stale_ticks"] = 0
        else:
            # 无真实变更 → 递增
            stale = self._stale_ticks.get(project_id, 0) + 1
            self._stale_ticks[project_id] = stale
            result["stale_ticks"] = stale

            if stale >= self.zombie_threshold and not self._alerted.get(
                    project_id):
                # 写告警
                self._write_alert(db_path, project_id, tick_num, stale)
                self._alerted[project_id] = True
                result["zombie"] = True
                result["healthy"] = False
                result["alert_written"] = True
            elif self._alerted.get(project_id):
                # 已告警但不再重复
                result["zombie"] = True
                result["healthy"] = False

        return result

    def _write_alert(self, db_path: Path, project_id: str,
                     tick_num: int, stale_ticks: int) -> None:
        """写入僵尸告警 observation"""
        conn = get_connection(db_path)
        try:
            conn.execute("BEGIN IMMEDIATE")
            conn.execute(
                "INSERT INTO observations (task_id, observer, severity, body) "
                "VALUES (?,?,?,?)",
                (None, "daemon", "warning",
                 json.dumps({
                     "type": "zombie_detected",
                     "project_id": project_id,
                     "stale_ticks": stale_ticks,
                     "threshold": self.zombie_threshold,
                     "tick": tick_num,
                     "message": f"项目 {project_id} 连续 {stale_ticks} tick 无真实变更",
                 })),
            )
            conn.execute(
                "INSERT INTO events (task_id, agent, event_type, detail) VALUES (?,?,?,?)",
                (None, "daemon", "agent_zombie_detected",
                 json.dumps({"project_id": project_id, "stale_ticks": stale_ticks})),
            )
            conn.commit()
        finally:
            conn.close()
        logger.warning(
            "Zombie detected: %s (stale=%d)",
            project_id,
            stale_ticks)

    def _write_resolution(self, db_path: Path, project_id: str,
                          tick_num: int) -> None:
        """解除僵尸告警"""
        conn = get_connection(db_path)
        try:
            conn.execute("BEGIN IMMEDIATE")
            conn.execute(
                "INSERT INTO observations (task_id, observer, severity, body) "
                "VALUES (?,?,?,?)",
                (None, "daemon", "info",
                 json.dumps({
                     "type": "zombie_resolved",
                     "project_id": project_id,
                     "tick": tick_num,
                     "message": f"项目 {project_id} 恢复活动",
                 })),
            )
            conn.commit()
        finally:
            conn.close()
        logger.info("Zombie resolved: %s", project_id)

    def get_status(self, project_id: str) -> Dict[str, Any]:
        """获取某个项目的当前健康状态"""
        return {
            "stale_ticks": self._stale_ticks.get(project_id, 0),
            "is_zombie": self._alerted.get(project_id, False),
        }