import logging
import os

from django.db import connections, transaction
from rest_framework.response import Response
from rest_framework.views import APIView

logger = logging.getLogger(__name__)


class HealthCheckView(APIView):
    """
    GET /api/v2/health/

    仅做最轻量的 DB 查询（SELECT 1）。
    若失败（含超时）：直接退出当前进程，让容器重启。
    """

    authentication_classes: list = []
    permission_classes: list = []

    # 单条查询超时（毫秒）。避免 health check 卡死占用 worker。
    STATEMENT_TIMEOUT_MS = 2000

    def get(self, request):
        try:
            # 用事务包住 SET LOCAL，确保 statement_timeout 只对本次请求生效
            with transaction.atomic(using="default"):
                with connections["default"].cursor() as cursor:
                    cursor.execute("SET LOCAL statement_timeout = %s;", [self.STATEMENT_TIMEOUT_MS])
                    cursor.execute("SELECT 1;")
                    cursor.fetchone()
        except Exception:
            logger.exception("api_v2 health check failed; exiting process")
            os._exit(1)  # 等价于 Go 的 os.Exit(1)：立即退出进程

        return Response({"status": "ok"})